SlideShare a Scribd company logo
State of the Art OpenGL
and Qt
Dr. Roland Krause
Integrated Computer Solutions
Abstract
OpenGL is a powerful, low level graphics toolkit with a steep learning curve that
allows access to accelerated GPU hardware. Using OpenGL developers achieve
high-fidelity, animated graphics ubiquitous in games, screen productions and
scientific software. Due to OpenGL’s native C-language API large scale,
professional software development endeavors wanting to utilize the advantages of
direct and accelerated graphics quickly become expensive and hard to maintain.
This presentation gives a comprehensive overview of the many aspects of
OpenGL development where Qt provides advanced interfaces that let the
developer focus on the tasks at hand instead of dealing with repetitive and error-
prone, platform dependent issues. From handling of Window related tasks,
providing type-safe data-structures for Vertex Array Objects to managing Shader
Programs, dealing with Textures, Frame Buffer Objects all the way to support for
Debugging and Profiling of OpenGL Applications we show solutions to the most
common issues any OpenGL program has to address.
We are able to demonstrate why Qt is the best C++ framework for development of
modern OpenGL based graphics applications.
Modern OpenGL with Qt
● OpenGL is an Application Programming Interface (API) for
Rendering Graphics in 2D and 3D
○ Widely used in CAD, Virtual Reality, Scientific Visualization, Information
Visualization, Flight Simulation, and Video Games.
○ Over 500 commands in Version 4.3
○ Managed by the non-profit technology consortium Khronos Group.
● Designed as a Streamlined, Hardware Independent
Interface
○ To be efficient usually implemented on graphics hardware (GPU)
○ Independent of Operating System or Windowing System, Cross-platform
○ No functions for windowing tasks, managing state, user input, 3D models
or reading image files
That’s where Qt comes into play!
Steps to Render a Scene with OpenGL
1. Create OpenGL Context and Window
2. Create and Manage the OpenGL Scene
○ Create Geometry
■ Store Geometry in Vertex Buffer Objects (VBOs)
○ Define, Compile and Link Shaders into a Shader
Program
○ Configure the Rendering Pipeline
○ Set Attribute Arrays, Uniforms, Textures, etc…
3. Render the Scene using OpenGL Primitives
Integration of OpenGL with Qt
● There are several possibilities when
integrating OpenGL Rendering with Qt
1. Native OpenGL rendering
using QWindow and QOpenGLContext
2. QOpenGLWindow
○ Wrapper for QWindow that hides complexity
○ Can be OpenGL Canvas with QPainter syntax
3. QOpenGLWidget
○ QWidget based applications
4. QQuickFramebufferObject
○ new since Qt-5.4
5. Rendering into the SceneGraph
6. Custom QQuickItem
5
Create OpenGL Context and Window
● Since Qt 5 the class QWindow represents a
window in the underlying windowing system
○ In Qt 4, QWidget had both Window and Widget
functionality
○ In Qt 5, QWindow is part of the gui module, QWidget is
in a separate and now optional module (widgets)
○ Applications will typically use QWidget or QQuickView
to create user interfaces
● It is possible to render directly to a
QWindow with a QOpenGLContext
● QWindow can be embedded in a QWidget
6
Qt’s OpenGL Support - QWindow
● Provides OpenGL and OpenGL ES Integration
○ QWindow supports rendering using (Desktop) OpenGL
and OpenGL ES, depending on platform support
● Derive class from QWindow
○ In Constructor set QWindow's surface type:
void QWindow::setSurfaceType(SurfaceType
surfaceType)
○ Choose Format Attributes using QSurfaceFormat
■ OpenGL version and profile, sample buffer size,
depth buffer size, etc..
○ Create a QOpenGLContext to manage the native
OpenGL context
7
● Create by calling QWindow::create()
● Implement a set of necessary functions
○ By convention: initializeGL(), updateGL(), resizeGL()
○ Needed to initialize and render OpenGL content
● Embed QWindow in a widget using QWidget::
createWindowContainer(...)
returns a QWidget with the QWindow embedded inside it
● Additionally Qt has QOpenGLPaintDevice
○ Enables use of OpenGL accelerated QPainter
rendering
Qt’s OpenGL Support - QWindow
8
Create OpenGL Context and Window
OpenGLWindow::OpenGLWindow(QScreen * screen) :
QWindow(screen)
{
setSurfaceType(OpenGLSurface);
QSurfaceFormat requestedFormat;
requestedFormat.setMajorVersion( 4 );
requestedFormat.setMinorVersion( 3 );
requestedFormat.setProfile(QSurfaceFormat::CoreProfile);
requestedFormat.setSamples( 4 ); // for MSAA
requestedFormat.setDepthBufferSize(24);
m_context = new QOpenGLContext;
m_context->setFormat( requestedFormat );
m_context->create();
setFormat( m_context->format() );
create();
}
9
QOpenGLWindow
● Convenience subclass of QWindow to perform
OpenGL painting
○ Enhanced QWindow that allows easily creating
windows that perform OpenGL rendering
○ API compatible with QOpenGLWidget and similar to
the legacy QGLWidget.
○ No dependency on widgets module and better
performance.
○ Optionally backed by a framebuffer object
○ Default behavior (and thus performance) is equivalent
to QWindow.
10
Using QOpenGLWindow
● Subclass QOpenGLWindow and reimplement
the following virtual functions:
○ initializeGL() to perform OpenGL resource initialization
○ resizeGL() to set up the transformation matrices and
other window size dependent resources
○ paintGL() to issue OpenGL commands or draw using
QPainter
● To schedule a repaint, call update()
○ Note that this will not immediately result in a call to
paintGL().
○ This is a slot so it can be connected to a QTimer::
timeout() signal to perform animation.
11
QOpenGLWindow using QPainter
● QOpenGLWindow inherits
QPaintDeviceWindow
● Allows opening a painter on itself and perform
QPainter-based drawing:
void paintGL() {
QOpenGLFunctions *f = context()->functions();
f->glClear(GL_COLOR_BIT | GL_DEPTH_BUFFER_BIT);
// issue some native OpenGL commands
QPainter p(this);
// draw using QPainter
// animate continuously: schedule an update
update();
}
12
Example: QOpenGLWindow-QPainter
13
● State machine that stores all data related to
the OpenGL rendering state
○ Most OpenGL functions set or retrieve some state
○ Creating a window and an OpenGL context is not part
of the OpenGL specification
● QOpenGLContext represents a native
OpenGL context
○ Enables OpenGL rendering on a QSurface.
○ Context allow to share resources with other contexts
with setShareContext()
OpenGL Context
14
QOpenGLContext
To create:
● Create a QSurfaceFormat object
○ Set desired OpenGL version and profile
● Create the QOpenGLContext
○ Set the context format using the QSurfaceFormat
object
● Finally call QOpenGLContext::create()
○ Use return value or isValid() to check if the context was
successfully initialized
● Before using any OpenGL QOpenGLContext
must be made current against a surface
○ QOpenGLContext::makeCurrent(QSurface*)
15
● When OpenGL rendering is done
○ Call swapBuffers() to swap the front and back buffers
of the surface at the end of the update function
○ Newly rendered content becomes visible
○ QOpenGLContext requires to call makeCurrent() again
before starting rendering a new frame, after calling
swapBuffers()
● Use QOpenGLContext::format() to retrieve info
on the context
○ Returns a QSurfaceFormat
○ OpenGL version, profile, etc...
QOpenGLContext
16
Qt’s OpenGL Support
● QOpenGLFunctions are convenience classes
● Simplify writing of OpenGL code
● Hide complexities of extension handling
● Hide differences between OpenGL ES 2 and
desktop OpenGL
○ Allow the use of OpenGL ES 2 functions on Desktop
OpenGL
○ No need to manually resolve OpenGL function pointers
○ Allowing cross-platform development of applications
targeting mobile or embedded devices
17
QAbstractOpenGLFunctions
● Family of classes that expose all functions for
a given OpenGL version and profile
○ OpenGL implementations on different platforms are
able to link to a variable number of OpenGL functions
depending upon the OpenGL ABI on that platform
○ On many platforms most functions must be resolved at
runtime, Options are:
■ Work with raw function pointers:
QOpenGLContext::getProcAddress()
■ Use QOpenGLFunctions and only expose those
functions common to OpenGL ES 2 and desktop
OpenGL
18
QAbstractOpenGLFunctions (cont.)
● Provides better support for newer versions of
OpenGL (especially 3.0 and higher)
● Ease development of desktop applications
relying on modern, desktop-only OpenGL
features
● QOpenGLFunctions_X_Y_PROFILE
○ Core and Compatibility Profiles
○ Expose every core OpenGL function by way of a
corresponding member function
○ Class for every valid combination of OpenGL version
and profile following the naming convention:
QOpenGLFunctions_<MAJOR VERSION>_<MINOR VERSION>[_PROFILE]
19
● Ensure QOpenGLContext is current before
using it
● Call
QOpenGLFunctions_X_Y_PROFILE::initializeOpenGLFunctions()
once before using it to resolve function
pointers
Using QOpenGLFunctions_X_Y_PROFILE
20
Qt’s OpenGL Support
● Classes that wrap native OpenGL Resources
○ QOpenGLBuffer, QOpenGLFramebufferObject
QOpenGLShaderProgram, OpenGLTexture,
QOpenGLVertexArrayObject
● Qt GUI Module Contains
○ QMatrix4x4, QVector4D and QQuaternion
○ Support common mathematical operations for 3D
graphics
● Miscellaneous
○ Debugging, QOpenGLDebugLogger
○ Timing, QOpenGLTimeMonitor, QOpenGLTimerQuery
21
QOpenGLDebugLogger
QOpenGLDebugMessage
QOpenGLTimeMonitor
QOpenGLTimerQuery
QOpenGLPaintDevice
QOpenGLTexture (Qt 5.3)
QOpenGLWidget(Qt 5.4)
QOpenGLWindow(Qt 5.4)
QOpenGLContext
QOpenGLContextGroup
QOpenGLVersionProfile
QOpenGLFunctions*
QOpenGLVertexArrayObject
QOpenGLBuffer
QOpenGLShader
QOpenGLShaderProgram
QOpenGLFrameBufferObject
QOpenGLFrameBufferObjectFormat
Qt 5 and OpenGL Classes
22
● Small program that runs on the GPU
● Ran as part of the OpenGL pipeline
● Programmable
● Coded in GLSL (OpenGL Shading Language)
● Makes rendering infinitely flexible
What is a Shader?
23
Simplified Pipeline
24
Shaders
● Two kinds of shaders:
○ Shaders that deal with Vertices, i.E:
Vertex, Tessellation and Geometry shaders determine
where on the screen a primitive is.
○ Fragment Shader uses that information to determine
what color that fragment will be.
● Must have a version identifier at top of file
● Must have a main() function
● Each shader is compiled, then they are linked
together to make a shader program
● Input/output interfaces must match, and are
checked at link time
25
● Vertex Shader
○ Executed once for every vertex
○ Input: Content of Vertex Buffer Arrays and Uniforms
○ Output: Vertex position
● Fragment Shader
○ Executed once for every fragment
○ Input: Result of Rasterization after Vertex Shader
○ Output: Candidate pixel color (aka Fragment)
Shader Basics
26
● Preparing Shaders
○ Compile vertex shader
○ Compile fragment shader
○ Configure attribute locations before linking
○ Link both shaders into a shader program
● Preparing shaders with Qt vs pure OpenGL
○ Much less code
○ Less error prone
Prepare Shaders
27
Example: Use Qt to Create Shader Program
void OpenGLUtilities::createShaderProgram() {
const GLubyte * _v=glGetString(GL_SHADING_LANGUAGE_VERSION);
QByteArray _vstr; _vstr.append(_v[0]); _vstr.append(_v[2]); _vstr.append(_v[3]);
int _vnumber=_vstr.toInt();
QByteArray version = "#version " + _vstr;
bool isOpenGLES=(QOpenGLContext::openGLModuleType() == QOpenGLContext::LibGLES);
if (_vnumber < 300) {
version = isOpenGLES ? "#version 100" : "#version 120";
}
version += "n";
QFile vtFile(":/vertex.vsh"); vtFile.open((QIODevice::ReadOnly | QIODevice::Text));
QFile fsFile (":/fragment.fsh"); fsFile.open((QIODevice::ReadOnly | QIODevice::Text));
if (!m_shaderProgram.addShaderFromSourceCode(QOpenGLShader::Vertex,version+vtFile.readAll())){
qDebug() << "Error in vertex shader:" << m_shaderProgram.log(); exit(1);
}
if (!m_shaderProgram.addShaderFromSourceCode(QOpenGLShader::Fragment,version+fsFile.readAll()))
{
qDebug() << "Error in fragment shader:" << m_shaderProgram.log(); exit(1);
}
if (_vnumber < 300) {
m_shaderProgram.bindAttributeLocation("vertexPosition", 0);
m_shaderProgram.bindAttributeLocation("vertexNormal", 1);
}
if ( !m_shaderProgram.link() ) {
qDebug() << "Error linking shader program:" << m_shaderProgram.log(); exit(1);
}
}
● Create buffer object
● Bind the buffer, making it the active buffer
● Copy the data to the buffer
// Triangle vertices
float vertices[] = {
-1.0f, -1.0f, 0.0f,
1.0f, -1.0f, 0.0f,
0.0f, 0.6f, 0.0f
};
// Create a static buffer for vertex data
m_vertexBuffer.create();
// Set usage pattern to Static Draw, (the data won't change)
m_vertexBuffer.setUsagePattern( QOpenGLBuffer::StaticDraw );
// Bind the buffer to the current OpenGL context
m_vertexBuffer.bind();
// Copy the data to the buffer
m_vertexBuffer.allocate( vertices, 3 * 3 * sizeof( float ) );
Creating a VBO
29
Vertex Attributes
● We have the data (in VBOs)
● We have the shaders compiled
● How do we map the data to the shader
attributes?
After compiling shaders before linking:
m_shaderProgram.bindAttributeLocation("vertexPosition", 0);
This assigns the attribute vertexPosition the
first location (0)
30
● VBO data is mapped to shader attribute
locations
m_shaderProgram.bind();
m_vertexBuffer.bind();
int vertexLocation = m_shaderProgram.attributeLocation("vertexPosition");
m_shaderProgram.setAttributeBuffer(
vertexLocation, // layout location
GL_FLOAT, // data's type
0, // Offset to data in buffer
3); // number of components (3 for x,y,z)
○ Bind the shader program
○ Bind the VBO containing the attribute data
○ Enable the desired vertex attribute array location
○ Set the attribute buffer to desired attribute location, set
number of components and stride
○ Supports VBOs with interleaved data
Vertex Attribute Arrays
31
Defining Uniform Values in Qt
● Yep, It is that simple! OpenGLShaderProgram
has a myriad ways to do it, e.g.: m_shaderProgram.
bind();
// Get the location of uniform value "uni" in the shader.
int uniLocation = m_shaderProgram.uniformLocation("uni");
// Then update the value m_shaderProgram.
setUniformValue(uniLocation,uniValue);
// Or in one step m_shaderProgram.setUniformValue
("uni",0.8f,0.5f,0.5f);
● If the value changes during an animation this
code would go in the updateGL function
● If it is static it could go into initializeGL after the
shader program has been linked and bound
32
Deprecated OpenGL Matrix Stack
● OpenGL Desktop version < 3 used to have
“built in” matrix stacks and related functionality
for dealing with transformations and
projections
○ glRotate*, glTranslate*, glScale*
○ glMatrixMode(), glPushMatrix(), glPopMatrix()
○ glLoadIdentity()
○ glFrustum(), gluPerspective(...), gluLookAt(..)
● All of these are now deprecated and
should/can no longer be used
33
● Fortunately, it is very easy to achieve the
same functionality with more flexibility using Qt
● There are functions to:
○ Create or set a matrix to the identity matrix
■ Identity matrix is a diagonal matrix with all elements
being 1. When multiplied with a vector the result will
be the same vector.
○ Translate, Scale, Rotate
○ Create a (view) matrix representing a “camera”
○ Create perspective or orthographic projection matrix
● And then one can use QStack, QVector, QList
and gain ultimate flexibility
Matrices, Qt to the Rescue
34
● Contains convenient functions for handling
Model, View, and Projection Matrices
○ QMatrix4x4::translate()
○ QMatrix4x4::scale()
○ QMatrix4x4::rotate()
○ QMatrix4x4::lookAt()
○ QMatrix4x4::perspective()
○ QMatrix4x4::ortho()
QMatrix4x4
35
● Qt- 5.2 introduces QOpenGLTexture to encapsulate an
OpenGL texture object
○ Makes it easy to work with OpenGL textures
○ Simplifies dealing with dependencies upon the capabilities of an OpenGL
implementation
● Typical usage pattern for QOpenGLTexture is
○ Instantiate the object specifying the texture target type
○ Set properties that affect storage requirements e.g. storage format,
dimensions
○ Allocate server-side storage
○ Optionally upload pixel data
○ Optionally set any additional properties e.g. filtering and border options
○ Render with texture or render to texture
○ In the common case of simply using a QImage as the source of texture
pixel data most of the above steps are performed automatically.
QOpenGLTexture
36
● Qt simplifies the process with:
○ QOpenGLFramebufferObject class
▪ Represents OpenGL FBO
▪ By default creates 2D texture for rendering target
▪ Function to return the OpenGL texture id
● Can be used for texture rendering
▪ Function to return rendered scene as a QImage
○ QOpenGLFramebufferObjectFormat()
▪ Specify format and attachments of FBO
Qt Support for FBO
37
Qt and OpenGL Extensions
● A list of all OpenGL extensions supported by the current
context can be retrieved with a call to
QSet<QByteArray> QOpenGLContext::​extensions() const
The context or a sharing context must be current.
● Resolve the entry points if the extension introduces a new
API: QOpenGLContext::getProcAddress().
● QtOpenGLExtensions module contains a class for every
OpenGL extension in the Khronos registry that introduces
new API.
38
OpenGL Debugging with Qt
● OpenGL programming can be error prone
○ Black screen syndrom. There is no indication what is going on?
○ To be sure that no errors are being returned from OpenGL
implementation check glGetError after every API call
○ OpenGL errors stack up so need to use this in a loop.
○ Additional information e.g. performance issues, warnings about using
deprecated APIs are not reported through the ordinary OpenGL error
reporting mechanisms
● QOpenGLDebugLogger enables logging of OpenGL
debugging messages
○ Provides access to the OpenGL debug log if OpenGL implementation
supports it (by exposing the GL_KHR_debug extension)
○ Messages from the OpenGL server will either be logged in an internal
OpenGL log or passed in "real-time", i.e. as they're generated from
OpenGL, to listeners
39
OpenGL Debugging with Qt
● Creating an OpenGL Debug Context
○ OpenGL implementations are allowed not to create any debug output at
all, unless the OpenGL context is a debug context
○ Set QSurfaceFormat::DebugContext format option on the
QSurfaceFormat used to create the QOpenGLContext object:
format.setOption(QSurfaceFormat::DebugContext);
● Creating and Initializing a QOpenGLDebugLogger
○ QOpenGLDebugLogger is a simple QObject-derived class
○ Create an instance and initialize it before usage by calling
initialize() with a current OpenGL context:
QOpenGLContext *ctx = QOpenGLContext::currentContext();
QOpenGLDebugLogger *logger = new QOpenGLDebugLogger(this);
logger->initialize();
○ Note that GL_KHR_debug extension must be available in the context in
order to access the messages logged by OpenGL
○ You can check the presence of this extension by calling:
ctx->hasExtension(QByteArrayLiteral("GL_KHR_debug")) 40
Qt OpenGL Debug Messages
● Reading the Internal OpenGL Debug Log
○ Messages stored in the internal log of debug messages can be retrieved
by using the loggedMessages() function
QList<QOpenGLDebugMessage> messages = logger->loggedMessages();
foreach (const QOpenGLDebugMessage &message, messages)
qDebug() << message;
○ Internal log has limited size; Older messages will get discarded to make
room for new incoming messages
● Real-time logging of messages
○ Receive a stream of debug messages from the OpenGL server as they
are generated by the implementation
○ Connect a slot to the messageLogged() signal, and start logging by
calling startLogging():
connect(logger, &QOpenGLDebugLogger::messageLogged, receiver,
&LogHandler::handleLoggedMessage);
logger->startLogging();
● Similarly, logging can be disabled at any time by calling the stopLogging()
function.
41
● Measure GPU execution time of OpenGL calls
● Use to profile an application’s rendering
performance
● Timed results in nanoseconds
● Create and set number of samples that will be
taken, e.g:
m_timeMonitor = new QOpenGLTimeMonitor(this);
m_timeMonitor->setSampleCount(3);
if (!m_timeMonitor->create())
...Handle error
QOpenGLTimeMonitor
42
● QOpenGLTimeMonitor::recordSample() to
record interval
m_timeMonitor->recordSample();
glClear( GL_COLOR_BUFFER_BIT );
m_timeMonitor->recordSample();
glDrawArrays( GL_TRIANGLES, 0, 3 );
m_timeMonitor->recordSample();
QOpenGLTimeMonitor
43
● Call waitForSamples() or waitForIntervals()
to retrieve samples or intervals
(in nanoseconds)
QVector<GLuint64> samples = m_timeMonitor->waitForSamples();
QVector<GLuint64> intervals = m_timeMonitor->waitForIntervals();
o These functions block until values are ready
o Call isResultAvailable() to prevent blocking
● Reset to use again
m_timeMonitor->reset();
QOpenGLTimeMonitor
44
Conclusion
● Qt has many classes that make working with
OpenGL much more efficient.
● Cross platform capabilities of Qt enhance the
portability of OpenGL applications greatly.
● Developer efficiency translates directly to
maintenance costs and time to market.
● Ideal for scientific applications, visualization
and even some games.

More Related Content

What's hot

Introduction to Qt
Introduction to QtIntroduction to Qt
Introduction to Qt
Puja Pramudya
 
Hello, QML
Hello, QMLHello, QML
Hello, QML
Jack Yang
 
Advanced Scenegraph Rendering Pipeline
Advanced Scenegraph Rendering PipelineAdvanced Scenegraph Rendering Pipeline
Advanced Scenegraph Rendering Pipeline
Narann29
 
Practical QML - Key Navigation, Dynamic Language and Theme Change
Practical QML - Key Navigation, Dynamic Language and Theme ChangePractical QML - Key Navigation, Dynamic Language and Theme Change
Practical QML - Key Navigation, Dynamic Language and Theme Change
Burkhard Stubert
 
Practical Spherical Harmonics Based PRT Methods
Practical Spherical Harmonics Based PRT MethodsPractical Spherical Harmonics Based PRT Methods
Practical Spherical Harmonics Based PRT Methods
Naughty Dog
 
Qt and QML performance tips & tricks for Qt 4.7
Qt and QML performance tips & tricks for Qt 4.7Qt and QML performance tips & tricks for Qt 4.7
Qt and QML performance tips & tricks for Qt 4.7
Pasi Kellokoski
 
Best Practices in Qt Quick/QML - Part II
Best Practices in Qt Quick/QML - Part IIBest Practices in Qt Quick/QML - Part II
Best Practices in Qt Quick/QML - Part II
ICS
 
Z Buffer Optimizations
Z Buffer OptimizationsZ Buffer Optimizations
Z Buffer Optimizations
pjcozzi
 
Tips and experience of DX12 Engine development .
Tips and experience of DX12 Engine development .Tips and experience of DX12 Engine development .
Tips and experience of DX12 Engine development .
YEONG-CHEON YOU
 
Using Multi-Touch and Gestures with Qt
Using Multi-Touch and Gestures with QtUsing Multi-Touch and Gestures with Qt
Using Multi-Touch and Gestures with Qt
account inactive
 
Introduction to QML
Introduction to QMLIntroduction to QML
Introduction to QML
Alan Uthoff
 
Approaching zero driver overhead
Approaching zero driver overheadApproaching zero driver overhead
Approaching zero driver overhead
Cass Everitt
 
QVariant, QObject — Qt's not just for GUI development
QVariant, QObject — Qt's not just for GUI developmentQVariant, QObject — Qt's not just for GUI development
QVariant, QObject — Qt's not just for GUI development
ICS
 
NVIDIA OpenGL in 2016
NVIDIA OpenGL in 2016NVIDIA OpenGL in 2016
NVIDIA OpenGL in 2016
Mark Kilgard
 
Shiny PC Graphics in Battlefield 3
Shiny PC Graphics in Battlefield 3Shiny PC Graphics in Battlefield 3
Shiny PC Graphics in Battlefield 3
Electronic Arts / DICE
 
Shader model 5 0 and compute shader
Shader model 5 0 and compute shaderShader model 5 0 and compute shader
Shader model 5 0 and compute shader
zaywalker
 
East Coast DevCon 2014: Concurrency & Parallelism in UE4 - Tips for programmi...
East Coast DevCon 2014: Concurrency & Parallelism in UE4 - Tips for programmi...East Coast DevCon 2014: Concurrency & Parallelism in UE4 - Tips for programmi...
East Coast DevCon 2014: Concurrency & Parallelism in UE4 - Tips for programmi...
Gerke Max Preussner
 
Linux Internals - Part II
Linux Internals - Part IILinux Internals - Part II
Linux Internals - Part II
Emertxe Information Technologies Pvt Ltd
 
Interpreter, Compiler, JIT from scratch
Interpreter, Compiler, JIT from scratchInterpreter, Compiler, JIT from scratch
Interpreter, Compiler, JIT from scratch
National Cheng Kung University
 
Best Practices in Qt Quick/QML - Part 3
Best Practices in Qt Quick/QML - Part 3Best Practices in Qt Quick/QML - Part 3
Best Practices in Qt Quick/QML - Part 3
ICS
 

What's hot (20)

Introduction to Qt
Introduction to QtIntroduction to Qt
Introduction to Qt
 
Hello, QML
Hello, QMLHello, QML
Hello, QML
 
Advanced Scenegraph Rendering Pipeline
Advanced Scenegraph Rendering PipelineAdvanced Scenegraph Rendering Pipeline
Advanced Scenegraph Rendering Pipeline
 
Practical QML - Key Navigation, Dynamic Language and Theme Change
Practical QML - Key Navigation, Dynamic Language and Theme ChangePractical QML - Key Navigation, Dynamic Language and Theme Change
Practical QML - Key Navigation, Dynamic Language and Theme Change
 
Practical Spherical Harmonics Based PRT Methods
Practical Spherical Harmonics Based PRT MethodsPractical Spherical Harmonics Based PRT Methods
Practical Spherical Harmonics Based PRT Methods
 
Qt and QML performance tips & tricks for Qt 4.7
Qt and QML performance tips & tricks for Qt 4.7Qt and QML performance tips & tricks for Qt 4.7
Qt and QML performance tips & tricks for Qt 4.7
 
Best Practices in Qt Quick/QML - Part II
Best Practices in Qt Quick/QML - Part IIBest Practices in Qt Quick/QML - Part II
Best Practices in Qt Quick/QML - Part II
 
Z Buffer Optimizations
Z Buffer OptimizationsZ Buffer Optimizations
Z Buffer Optimizations
 
Tips and experience of DX12 Engine development .
Tips and experience of DX12 Engine development .Tips and experience of DX12 Engine development .
Tips and experience of DX12 Engine development .
 
Using Multi-Touch and Gestures with Qt
Using Multi-Touch and Gestures with QtUsing Multi-Touch and Gestures with Qt
Using Multi-Touch and Gestures with Qt
 
Introduction to QML
Introduction to QMLIntroduction to QML
Introduction to QML
 
Approaching zero driver overhead
Approaching zero driver overheadApproaching zero driver overhead
Approaching zero driver overhead
 
QVariant, QObject — Qt's not just for GUI development
QVariant, QObject — Qt's not just for GUI developmentQVariant, QObject — Qt's not just for GUI development
QVariant, QObject — Qt's not just for GUI development
 
NVIDIA OpenGL in 2016
NVIDIA OpenGL in 2016NVIDIA OpenGL in 2016
NVIDIA OpenGL in 2016
 
Shiny PC Graphics in Battlefield 3
Shiny PC Graphics in Battlefield 3Shiny PC Graphics in Battlefield 3
Shiny PC Graphics in Battlefield 3
 
Shader model 5 0 and compute shader
Shader model 5 0 and compute shaderShader model 5 0 and compute shader
Shader model 5 0 and compute shader
 
East Coast DevCon 2014: Concurrency & Parallelism in UE4 - Tips for programmi...
East Coast DevCon 2014: Concurrency & Parallelism in UE4 - Tips for programmi...East Coast DevCon 2014: Concurrency & Parallelism in UE4 - Tips for programmi...
East Coast DevCon 2014: Concurrency & Parallelism in UE4 - Tips for programmi...
 
Linux Internals - Part II
Linux Internals - Part IILinux Internals - Part II
Linux Internals - Part II
 
Interpreter, Compiler, JIT from scratch
Interpreter, Compiler, JIT from scratchInterpreter, Compiler, JIT from scratch
Interpreter, Compiler, JIT from scratch
 
Best Practices in Qt Quick/QML - Part 3
Best Practices in Qt Quick/QML - Part 3Best Practices in Qt Quick/QML - Part 3
Best Practices in Qt Quick/QML - Part 3
 

Similar to State of the Art OpenGL and Qt

Qt Programming on TI Processors
Qt Programming on TI ProcessorsQt Programming on TI Processors
Qt Programming on TI Processors
Prabindh Sundareson
 
OpenGL Introduction.
OpenGL Introduction.OpenGL Introduction.
OpenGL Introduction.
Girish Ghate
 
Open gl
Open glOpen gl
Open gl
ch samaram
 
openGL basics for sample program (1).ppt
openGL basics for sample program (1).pptopenGL basics for sample program (1).ppt
openGL basics for sample program (1).ppt
HIMANKMISHRA2
 
openGL basics for sample program.ppt
openGL basics for sample program.pptopenGL basics for sample program.ppt
openGL basics for sample program.ppt
HIMANKMISHRA2
 
Project meeting: Android Graphics Architecture Overview
Project meeting: Android Graphics Architecture OverviewProject meeting: Android Graphics Architecture Overview
Project meeting: Android Graphics Architecture Overview
Yu-Hsin Hung
 
Baiscs of OpenGL
Baiscs of OpenGLBaiscs of OpenGL
Baiscs of OpenGL
Mrinmoy Dalal
 
Necessitas - Qt on Android - from FSCONS 2011
Necessitas - Qt on Android - from FSCONS 2011Necessitas - Qt on Android - from FSCONS 2011
Necessitas - Qt on Android - from FSCONS 2011
Johan Thelin
 
Opengl (1)
Opengl (1)Opengl (1)
Opengl (1)
ch samaram
 
Lecture 6 introduction to open gl and glut
Lecture 6   introduction to open gl and glutLecture 6   introduction to open gl and glut
Lecture 6 introduction to open gl and glut
simpleok
 
18csl67 vtu lab manual
18csl67 vtu lab manual18csl67 vtu lab manual
18csl67 vtu lab manual
NatsuDragoneel5
 
Qt for beginners part 4 doing more
Qt for beginners part 4   doing moreQt for beginners part 4   doing more
Qt for beginners part 4 doing more
ICS
 
Opengl basics
Opengl basicsOpengl basics
Opengl basics
pushpa latha
 
COMPUTER GRAPHICS PROJECT REPORT
COMPUTER GRAPHICS PROJECT REPORTCOMPUTER GRAPHICS PROJECT REPORT
COMPUTER GRAPHICS PROJECT REPORT
vineet raj
 
Webrender 1.0
Webrender 1.0Webrender 1.0
Webrender 1.0
Daosheng Mu
 
Dynamic sorting algorithm vizualizer.pdf
Dynamic sorting algorithm vizualizer.pdfDynamic sorting algorithm vizualizer.pdf
Dynamic sorting algorithm vizualizer.pdf
AgneshShetty
 
OpenGL Fixed Function to Shaders - Porting a fixed function application to “m...
OpenGL Fixed Function to Shaders - Porting a fixed function application to “m...OpenGL Fixed Function to Shaders - Porting a fixed function application to “m...
OpenGL Fixed Function to Shaders - Porting a fixed function application to “m...
ICS
 
Introduction of openGL
Introduction  of openGLIntroduction  of openGL
Introduction of openGL
Gary Yeh
 
Computer Graphics - Lecture 01 - 3D Programming I
Computer Graphics - Lecture 01 - 3D Programming IComputer Graphics - Lecture 01 - 3D Programming I
Computer Graphics - Lecture 01 - 3D Programming I
💻 Anton Gerdelan
 
3D Programming Basics: WebGL
3D Programming Basics: WebGL3D Programming Basics: WebGL
3D Programming Basics: WebGL
Globant
 

Similar to State of the Art OpenGL and Qt (20)

Qt Programming on TI Processors
Qt Programming on TI ProcessorsQt Programming on TI Processors
Qt Programming on TI Processors
 
OpenGL Introduction.
OpenGL Introduction.OpenGL Introduction.
OpenGL Introduction.
 
Open gl
Open glOpen gl
Open gl
 
openGL basics for sample program (1).ppt
openGL basics for sample program (1).pptopenGL basics for sample program (1).ppt
openGL basics for sample program (1).ppt
 
openGL basics for sample program.ppt
openGL basics for sample program.pptopenGL basics for sample program.ppt
openGL basics for sample program.ppt
 
Project meeting: Android Graphics Architecture Overview
Project meeting: Android Graphics Architecture OverviewProject meeting: Android Graphics Architecture Overview
Project meeting: Android Graphics Architecture Overview
 
Baiscs of OpenGL
Baiscs of OpenGLBaiscs of OpenGL
Baiscs of OpenGL
 
Necessitas - Qt on Android - from FSCONS 2011
Necessitas - Qt on Android - from FSCONS 2011Necessitas - Qt on Android - from FSCONS 2011
Necessitas - Qt on Android - from FSCONS 2011
 
Opengl (1)
Opengl (1)Opengl (1)
Opengl (1)
 
Lecture 6 introduction to open gl and glut
Lecture 6   introduction to open gl and glutLecture 6   introduction to open gl and glut
Lecture 6 introduction to open gl and glut
 
18csl67 vtu lab manual
18csl67 vtu lab manual18csl67 vtu lab manual
18csl67 vtu lab manual
 
Qt for beginners part 4 doing more
Qt for beginners part 4   doing moreQt for beginners part 4   doing more
Qt for beginners part 4 doing more
 
Opengl basics
Opengl basicsOpengl basics
Opengl basics
 
COMPUTER GRAPHICS PROJECT REPORT
COMPUTER GRAPHICS PROJECT REPORTCOMPUTER GRAPHICS PROJECT REPORT
COMPUTER GRAPHICS PROJECT REPORT
 
Webrender 1.0
Webrender 1.0Webrender 1.0
Webrender 1.0
 
Dynamic sorting algorithm vizualizer.pdf
Dynamic sorting algorithm vizualizer.pdfDynamic sorting algorithm vizualizer.pdf
Dynamic sorting algorithm vizualizer.pdf
 
OpenGL Fixed Function to Shaders - Porting a fixed function application to “m...
OpenGL Fixed Function to Shaders - Porting a fixed function application to “m...OpenGL Fixed Function to Shaders - Porting a fixed function application to “m...
OpenGL Fixed Function to Shaders - Porting a fixed function application to “m...
 
Introduction of openGL
Introduction  of openGLIntroduction  of openGL
Introduction of openGL
 
Computer Graphics - Lecture 01 - 3D Programming I
Computer Graphics - Lecture 01 - 3D Programming IComputer Graphics - Lecture 01 - 3D Programming I
Computer Graphics - Lecture 01 - 3D Programming I
 
3D Programming Basics: WebGL
3D Programming Basics: WebGL3D Programming Basics: WebGL
3D Programming Basics: WebGL
 

More from ICS

Secure-by-Design Using Hardware and Software Protection for FDA Compliance
Secure-by-Design Using Hardware and Software Protection for FDA ComplianceSecure-by-Design Using Hardware and Software Protection for FDA Compliance
Secure-by-Design Using Hardware and Software Protection for FDA Compliance
ICS
 
Webinar On-Demand: Using Flutter for Embedded
Webinar On-Demand: Using Flutter for EmbeddedWebinar On-Demand: Using Flutter for Embedded
Webinar On-Demand: Using Flutter for Embedded
ICS
 
A Deep Dive into Secure Product Development Frameworks.pdf
A Deep Dive into Secure Product Development Frameworks.pdfA Deep Dive into Secure Product Development Frameworks.pdf
A Deep Dive into Secure Product Development Frameworks.pdf
ICS
 
The Real-World Challenges of Medical Device Cybersecurity- Mitigating Vulnera...
The Real-World Challenges of Medical Device Cybersecurity- Mitigating Vulnera...The Real-World Challenges of Medical Device Cybersecurity- Mitigating Vulnera...
The Real-World Challenges of Medical Device Cybersecurity- Mitigating Vulnera...
ICS
 
Practical Advice for FDA’s 510(k) Requirements.pdf
Practical Advice for FDA’s 510(k) Requirements.pdfPractical Advice for FDA’s 510(k) Requirements.pdf
Practical Advice for FDA’s 510(k) Requirements.pdf
ICS
 
Accelerating Development of a Safety-Critical Cobot Welding System with Qt/QM...
Accelerating Development of a Safety-Critical Cobot Welding System with Qt/QM...Accelerating Development of a Safety-Critical Cobot Welding System with Qt/QM...
Accelerating Development of a Safety-Critical Cobot Welding System with Qt/QM...
ICS
 
Overcoming CMake Configuration Issues Webinar
Overcoming CMake Configuration Issues WebinarOvercoming CMake Configuration Issues Webinar
Overcoming CMake Configuration Issues Webinar
ICS
 
Enhancing Quality and Test in Medical Device Design - Part 2.pdf
Enhancing Quality and Test in Medical Device Design - Part 2.pdfEnhancing Quality and Test in Medical Device Design - Part 2.pdf
Enhancing Quality and Test in Medical Device Design - Part 2.pdf
ICS
 
Designing and Managing IoT Devices for Rapid Deployment - Webinar.pdf
Designing and Managing IoT Devices for Rapid Deployment - Webinar.pdfDesigning and Managing IoT Devices for Rapid Deployment - Webinar.pdf
Designing and Managing IoT Devices for Rapid Deployment - Webinar.pdf
ICS
 
Quality and Test in Medical Device Design - Part 1.pdf
Quality and Test in Medical Device Design - Part 1.pdfQuality and Test in Medical Device Design - Part 1.pdf
Quality and Test in Medical Device Design - Part 1.pdf
ICS
 
Creating Digital Twins Using Rapid Development Techniques.pdf
Creating Digital Twins Using Rapid Development Techniques.pdfCreating Digital Twins Using Rapid Development Techniques.pdf
Creating Digital Twins Using Rapid Development Techniques.pdf
ICS
 
Secure Your Medical Devices From the Ground Up
Secure Your Medical Devices From the Ground Up Secure Your Medical Devices From the Ground Up
Secure Your Medical Devices From the Ground Up
ICS
 
Cybersecurity and Software Updates in Medical Devices.pdf
Cybersecurity and Software Updates in Medical Devices.pdfCybersecurity and Software Updates in Medical Devices.pdf
Cybersecurity and Software Updates in Medical Devices.pdf
ICS
 
MDG Panel - Creating Expert Level GUIs for Complex Medical Devices
MDG Panel - Creating Expert Level GUIs for Complex Medical DevicesMDG Panel - Creating Expert Level GUIs for Complex Medical Devices
MDG Panel - Creating Expert Level GUIs for Complex Medical Devices
ICS
 
How to Craft a Winning IOT Device Management Solution
How to Craft a Winning IOT Device Management SolutionHow to Craft a Winning IOT Device Management Solution
How to Craft a Winning IOT Device Management Solution
ICS
 
Bridging the Gap Between Development and Regulatory Teams
Bridging the Gap Between Development and Regulatory TeamsBridging the Gap Between Development and Regulatory Teams
Bridging the Gap Between Development and Regulatory Teams
ICS
 
IoT Device Fleet Management: Create a Robust Solution with Azure
IoT Device Fleet Management: Create a Robust Solution with AzureIoT Device Fleet Management: Create a Robust Solution with Azure
IoT Device Fleet Management: Create a Robust Solution with Azure
ICS
 
Basic Cmake for Qt Users
Basic Cmake for Qt UsersBasic Cmake for Qt Users
Basic Cmake for Qt Users
ICS
 
Software Update Mechanisms: Selecting the Best Solutin for Your Embedded Linu...
Software Update Mechanisms: Selecting the Best Solutin for Your Embedded Linu...Software Update Mechanisms: Selecting the Best Solutin for Your Embedded Linu...
Software Update Mechanisms: Selecting the Best Solutin for Your Embedded Linu...
ICS
 
Qt Installer Framework
Qt Installer FrameworkQt Installer Framework
Qt Installer Framework
ICS
 

More from ICS (20)

Secure-by-Design Using Hardware and Software Protection for FDA Compliance
Secure-by-Design Using Hardware and Software Protection for FDA ComplianceSecure-by-Design Using Hardware and Software Protection for FDA Compliance
Secure-by-Design Using Hardware and Software Protection for FDA Compliance
 
Webinar On-Demand: Using Flutter for Embedded
Webinar On-Demand: Using Flutter for EmbeddedWebinar On-Demand: Using Flutter for Embedded
Webinar On-Demand: Using Flutter for Embedded
 
A Deep Dive into Secure Product Development Frameworks.pdf
A Deep Dive into Secure Product Development Frameworks.pdfA Deep Dive into Secure Product Development Frameworks.pdf
A Deep Dive into Secure Product Development Frameworks.pdf
 
The Real-World Challenges of Medical Device Cybersecurity- Mitigating Vulnera...
The Real-World Challenges of Medical Device Cybersecurity- Mitigating Vulnera...The Real-World Challenges of Medical Device Cybersecurity- Mitigating Vulnera...
The Real-World Challenges of Medical Device Cybersecurity- Mitigating Vulnera...
 
Practical Advice for FDA’s 510(k) Requirements.pdf
Practical Advice for FDA’s 510(k) Requirements.pdfPractical Advice for FDA’s 510(k) Requirements.pdf
Practical Advice for FDA’s 510(k) Requirements.pdf
 
Accelerating Development of a Safety-Critical Cobot Welding System with Qt/QM...
Accelerating Development of a Safety-Critical Cobot Welding System with Qt/QM...Accelerating Development of a Safety-Critical Cobot Welding System with Qt/QM...
Accelerating Development of a Safety-Critical Cobot Welding System with Qt/QM...
 
Overcoming CMake Configuration Issues Webinar
Overcoming CMake Configuration Issues WebinarOvercoming CMake Configuration Issues Webinar
Overcoming CMake Configuration Issues Webinar
 
Enhancing Quality and Test in Medical Device Design - Part 2.pdf
Enhancing Quality and Test in Medical Device Design - Part 2.pdfEnhancing Quality and Test in Medical Device Design - Part 2.pdf
Enhancing Quality and Test in Medical Device Design - Part 2.pdf
 
Designing and Managing IoT Devices for Rapid Deployment - Webinar.pdf
Designing and Managing IoT Devices for Rapid Deployment - Webinar.pdfDesigning and Managing IoT Devices for Rapid Deployment - Webinar.pdf
Designing and Managing IoT Devices for Rapid Deployment - Webinar.pdf
 
Quality and Test in Medical Device Design - Part 1.pdf
Quality and Test in Medical Device Design - Part 1.pdfQuality and Test in Medical Device Design - Part 1.pdf
Quality and Test in Medical Device Design - Part 1.pdf
 
Creating Digital Twins Using Rapid Development Techniques.pdf
Creating Digital Twins Using Rapid Development Techniques.pdfCreating Digital Twins Using Rapid Development Techniques.pdf
Creating Digital Twins Using Rapid Development Techniques.pdf
 
Secure Your Medical Devices From the Ground Up
Secure Your Medical Devices From the Ground Up Secure Your Medical Devices From the Ground Up
Secure Your Medical Devices From the Ground Up
 
Cybersecurity and Software Updates in Medical Devices.pdf
Cybersecurity and Software Updates in Medical Devices.pdfCybersecurity and Software Updates in Medical Devices.pdf
Cybersecurity and Software Updates in Medical Devices.pdf
 
MDG Panel - Creating Expert Level GUIs for Complex Medical Devices
MDG Panel - Creating Expert Level GUIs for Complex Medical DevicesMDG Panel - Creating Expert Level GUIs for Complex Medical Devices
MDG Panel - Creating Expert Level GUIs for Complex Medical Devices
 
How to Craft a Winning IOT Device Management Solution
How to Craft a Winning IOT Device Management SolutionHow to Craft a Winning IOT Device Management Solution
How to Craft a Winning IOT Device Management Solution
 
Bridging the Gap Between Development and Regulatory Teams
Bridging the Gap Between Development and Regulatory TeamsBridging the Gap Between Development and Regulatory Teams
Bridging the Gap Between Development and Regulatory Teams
 
IoT Device Fleet Management: Create a Robust Solution with Azure
IoT Device Fleet Management: Create a Robust Solution with AzureIoT Device Fleet Management: Create a Robust Solution with Azure
IoT Device Fleet Management: Create a Robust Solution with Azure
 
Basic Cmake for Qt Users
Basic Cmake for Qt UsersBasic Cmake for Qt Users
Basic Cmake for Qt Users
 
Software Update Mechanisms: Selecting the Best Solutin for Your Embedded Linu...
Software Update Mechanisms: Selecting the Best Solutin for Your Embedded Linu...Software Update Mechanisms: Selecting the Best Solutin for Your Embedded Linu...
Software Update Mechanisms: Selecting the Best Solutin for Your Embedded Linu...
 
Qt Installer Framework
Qt Installer FrameworkQt Installer Framework
Qt Installer Framework
 

Recently uploaded

The Microsoft 365 Migration Tutorial For Beginner.pptx
The Microsoft 365 Migration Tutorial For Beginner.pptxThe Microsoft 365 Migration Tutorial For Beginner.pptx
The Microsoft 365 Migration Tutorial For Beginner.pptx
operationspcvita
 
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAU
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAUHCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAU
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAU
panagenda
 
Leveraging the Graph for Clinical Trials and Standards
Leveraging the Graph for Clinical Trials and StandardsLeveraging the Graph for Clinical Trials and Standards
Leveraging the Graph for Clinical Trials and Standards
Neo4j
 
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectors
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectorsConnector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectors
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectors
DianaGray10
 
“How Axelera AI Uses Digital Compute-in-memory to Deliver Fast and Energy-eff...
“How Axelera AI Uses Digital Compute-in-memory to Deliver Fast and Energy-eff...“How Axelera AI Uses Digital Compute-in-memory to Deliver Fast and Energy-eff...
“How Axelera AI Uses Digital Compute-in-memory to Deliver Fast and Energy-eff...
Edge AI and Vision Alliance
 
AppSec PNW: Android and iOS Application Security with MobSF
AppSec PNW: Android and iOS Application Security with MobSFAppSec PNW: Android and iOS Application Security with MobSF
AppSec PNW: Android and iOS Application Security with MobSF
Ajin Abraham
 
5th LF Energy Power Grid Model Meet-up Slides
5th LF Energy Power Grid Model Meet-up Slides5th LF Energy Power Grid Model Meet-up Slides
5th LF Energy Power Grid Model Meet-up Slides
DanBrown980551
 
HCL Notes and Domino License Cost Reduction in the World of DLAU
HCL Notes and Domino License Cost Reduction in the World of DLAUHCL Notes and Domino License Cost Reduction in the World of DLAU
HCL Notes and Domino License Cost Reduction in the World of DLAU
panagenda
 
GraphRAG for LifeSciences Hands-On with the Clinical Knowledge Graph
GraphRAG for LifeSciences Hands-On with the Clinical Knowledge GraphGraphRAG for LifeSciences Hands-On with the Clinical Knowledge Graph
GraphRAG for LifeSciences Hands-On with the Clinical Knowledge Graph
Neo4j
 
Deep Dive: AI-Powered Marketing to Get More Leads and Customers with HyperGro...
Deep Dive: AI-Powered Marketing to Get More Leads and Customers with HyperGro...Deep Dive: AI-Powered Marketing to Get More Leads and Customers with HyperGro...
Deep Dive: AI-Powered Marketing to Get More Leads and Customers with HyperGro...
saastr
 
Crafting Excellence: A Comprehensive Guide to iOS Mobile App Development Serv...
Crafting Excellence: A Comprehensive Guide to iOS Mobile App Development Serv...Crafting Excellence: A Comprehensive Guide to iOS Mobile App Development Serv...
Crafting Excellence: A Comprehensive Guide to iOS Mobile App Development Serv...
Pitangent Analytics & Technology Solutions Pvt. Ltd
 
Driving Business Innovation: Latest Generative AI Advancements & Success Story
Driving Business Innovation: Latest Generative AI Advancements & Success StoryDriving Business Innovation: Latest Generative AI Advancements & Success Story
Driving Business Innovation: Latest Generative AI Advancements & Success Story
Safe Software
 
Overcoming the PLG Trap: Lessons from Canva's Head of Sales & Head of EMEA Da...
Overcoming the PLG Trap: Lessons from Canva's Head of Sales & Head of EMEA Da...Overcoming the PLG Trap: Lessons from Canva's Head of Sales & Head of EMEA Da...
Overcoming the PLG Trap: Lessons from Canva's Head of Sales & Head of EMEA Da...
saastr
 
Taking AI to the Next Level in Manufacturing.pdf
Taking AI to the Next Level in Manufacturing.pdfTaking AI to the Next Level in Manufacturing.pdf
Taking AI to the Next Level in Manufacturing.pdf
ssuserfac0301
 
Skybuffer SAM4U tool for SAP license adoption
Skybuffer SAM4U tool for SAP license adoptionSkybuffer SAM4U tool for SAP license adoption
Skybuffer SAM4U tool for SAP license adoption
Tatiana Kojar
 
JavaLand 2024: Application Development Green Masterplan
JavaLand 2024: Application Development Green MasterplanJavaLand 2024: Application Development Green Masterplan
JavaLand 2024: Application Development Green Masterplan
Miro Wengner
 
Your One-Stop Shop for Python Success: Top 10 US Python Development Providers
Your One-Stop Shop for Python Success: Top 10 US Python Development ProvidersYour One-Stop Shop for Python Success: Top 10 US Python Development Providers
Your One-Stop Shop for Python Success: Top 10 US Python Development Providers
akankshawande
 
Biomedical Knowledge Graphs for Data Scientists and Bioinformaticians
Biomedical Knowledge Graphs for Data Scientists and BioinformaticiansBiomedical Knowledge Graphs for Data Scientists and Bioinformaticians
Biomedical Knowledge Graphs for Data Scientists and Bioinformaticians
Neo4j
 
Dandelion Hashtable: beyond billion requests per second on a commodity server
Dandelion Hashtable: beyond billion requests per second on a commodity serverDandelion Hashtable: beyond billion requests per second on a commodity server
Dandelion Hashtable: beyond billion requests per second on a commodity server
Antonios Katsarakis
 

Recently uploaded (20)

The Microsoft 365 Migration Tutorial For Beginner.pptx
The Microsoft 365 Migration Tutorial For Beginner.pptxThe Microsoft 365 Migration Tutorial For Beginner.pptx
The Microsoft 365 Migration Tutorial For Beginner.pptx
 
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAU
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAUHCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAU
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAU
 
Leveraging the Graph for Clinical Trials and Standards
Leveraging the Graph for Clinical Trials and StandardsLeveraging the Graph for Clinical Trials and Standards
Leveraging the Graph for Clinical Trials and Standards
 
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectors
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectorsConnector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectors
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectors
 
“How Axelera AI Uses Digital Compute-in-memory to Deliver Fast and Energy-eff...
“How Axelera AI Uses Digital Compute-in-memory to Deliver Fast and Energy-eff...“How Axelera AI Uses Digital Compute-in-memory to Deliver Fast and Energy-eff...
“How Axelera AI Uses Digital Compute-in-memory to Deliver Fast and Energy-eff...
 
AppSec PNW: Android and iOS Application Security with MobSF
AppSec PNW: Android and iOS Application Security with MobSFAppSec PNW: Android and iOS Application Security with MobSF
AppSec PNW: Android and iOS Application Security with MobSF
 
5th LF Energy Power Grid Model Meet-up Slides
5th LF Energy Power Grid Model Meet-up Slides5th LF Energy Power Grid Model Meet-up Slides
5th LF Energy Power Grid Model Meet-up Slides
 
HCL Notes and Domino License Cost Reduction in the World of DLAU
HCL Notes and Domino License Cost Reduction in the World of DLAUHCL Notes and Domino License Cost Reduction in the World of DLAU
HCL Notes and Domino License Cost Reduction in the World of DLAU
 
GraphRAG for LifeSciences Hands-On with the Clinical Knowledge Graph
GraphRAG for LifeSciences Hands-On with the Clinical Knowledge GraphGraphRAG for LifeSciences Hands-On with the Clinical Knowledge Graph
GraphRAG for LifeSciences Hands-On with the Clinical Knowledge Graph
 
Deep Dive: AI-Powered Marketing to Get More Leads and Customers with HyperGro...
Deep Dive: AI-Powered Marketing to Get More Leads and Customers with HyperGro...Deep Dive: AI-Powered Marketing to Get More Leads and Customers with HyperGro...
Deep Dive: AI-Powered Marketing to Get More Leads and Customers with HyperGro...
 
Crafting Excellence: A Comprehensive Guide to iOS Mobile App Development Serv...
Crafting Excellence: A Comprehensive Guide to iOS Mobile App Development Serv...Crafting Excellence: A Comprehensive Guide to iOS Mobile App Development Serv...
Crafting Excellence: A Comprehensive Guide to iOS Mobile App Development Serv...
 
Driving Business Innovation: Latest Generative AI Advancements & Success Story
Driving Business Innovation: Latest Generative AI Advancements & Success StoryDriving Business Innovation: Latest Generative AI Advancements & Success Story
Driving Business Innovation: Latest Generative AI Advancements & Success Story
 
Overcoming the PLG Trap: Lessons from Canva's Head of Sales & Head of EMEA Da...
Overcoming the PLG Trap: Lessons from Canva's Head of Sales & Head of EMEA Da...Overcoming the PLG Trap: Lessons from Canva's Head of Sales & Head of EMEA Da...
Overcoming the PLG Trap: Lessons from Canva's Head of Sales & Head of EMEA Da...
 
Artificial Intelligence and Electronic Warfare
Artificial Intelligence and Electronic WarfareArtificial Intelligence and Electronic Warfare
Artificial Intelligence and Electronic Warfare
 
Taking AI to the Next Level in Manufacturing.pdf
Taking AI to the Next Level in Manufacturing.pdfTaking AI to the Next Level in Manufacturing.pdf
Taking AI to the Next Level in Manufacturing.pdf
 
Skybuffer SAM4U tool for SAP license adoption
Skybuffer SAM4U tool for SAP license adoptionSkybuffer SAM4U tool for SAP license adoption
Skybuffer SAM4U tool for SAP license adoption
 
JavaLand 2024: Application Development Green Masterplan
JavaLand 2024: Application Development Green MasterplanJavaLand 2024: Application Development Green Masterplan
JavaLand 2024: Application Development Green Masterplan
 
Your One-Stop Shop for Python Success: Top 10 US Python Development Providers
Your One-Stop Shop for Python Success: Top 10 US Python Development ProvidersYour One-Stop Shop for Python Success: Top 10 US Python Development Providers
Your One-Stop Shop for Python Success: Top 10 US Python Development Providers
 
Biomedical Knowledge Graphs for Data Scientists and Bioinformaticians
Biomedical Knowledge Graphs for Data Scientists and BioinformaticiansBiomedical Knowledge Graphs for Data Scientists and Bioinformaticians
Biomedical Knowledge Graphs for Data Scientists and Bioinformaticians
 
Dandelion Hashtable: beyond billion requests per second on a commodity server
Dandelion Hashtable: beyond billion requests per second on a commodity serverDandelion Hashtable: beyond billion requests per second on a commodity server
Dandelion Hashtable: beyond billion requests per second on a commodity server
 

State of the Art OpenGL and Qt

  • 1. State of the Art OpenGL and Qt Dr. Roland Krause Integrated Computer Solutions
  • 2. Abstract OpenGL is a powerful, low level graphics toolkit with a steep learning curve that allows access to accelerated GPU hardware. Using OpenGL developers achieve high-fidelity, animated graphics ubiquitous in games, screen productions and scientific software. Due to OpenGL’s native C-language API large scale, professional software development endeavors wanting to utilize the advantages of direct and accelerated graphics quickly become expensive and hard to maintain. This presentation gives a comprehensive overview of the many aspects of OpenGL development where Qt provides advanced interfaces that let the developer focus on the tasks at hand instead of dealing with repetitive and error- prone, platform dependent issues. From handling of Window related tasks, providing type-safe data-structures for Vertex Array Objects to managing Shader Programs, dealing with Textures, Frame Buffer Objects all the way to support for Debugging and Profiling of OpenGL Applications we show solutions to the most common issues any OpenGL program has to address. We are able to demonstrate why Qt is the best C++ framework for development of modern OpenGL based graphics applications.
  • 3. Modern OpenGL with Qt ● OpenGL is an Application Programming Interface (API) for Rendering Graphics in 2D and 3D ○ Widely used in CAD, Virtual Reality, Scientific Visualization, Information Visualization, Flight Simulation, and Video Games. ○ Over 500 commands in Version 4.3 ○ Managed by the non-profit technology consortium Khronos Group. ● Designed as a Streamlined, Hardware Independent Interface ○ To be efficient usually implemented on graphics hardware (GPU) ○ Independent of Operating System or Windowing System, Cross-platform ○ No functions for windowing tasks, managing state, user input, 3D models or reading image files That’s where Qt comes into play!
  • 4. Steps to Render a Scene with OpenGL 1. Create OpenGL Context and Window 2. Create and Manage the OpenGL Scene ○ Create Geometry ■ Store Geometry in Vertex Buffer Objects (VBOs) ○ Define, Compile and Link Shaders into a Shader Program ○ Configure the Rendering Pipeline ○ Set Attribute Arrays, Uniforms, Textures, etc… 3. Render the Scene using OpenGL Primitives
  • 5. Integration of OpenGL with Qt ● There are several possibilities when integrating OpenGL Rendering with Qt 1. Native OpenGL rendering using QWindow and QOpenGLContext 2. QOpenGLWindow ○ Wrapper for QWindow that hides complexity ○ Can be OpenGL Canvas with QPainter syntax 3. QOpenGLWidget ○ QWidget based applications 4. QQuickFramebufferObject ○ new since Qt-5.4 5. Rendering into the SceneGraph 6. Custom QQuickItem 5
  • 6. Create OpenGL Context and Window ● Since Qt 5 the class QWindow represents a window in the underlying windowing system ○ In Qt 4, QWidget had both Window and Widget functionality ○ In Qt 5, QWindow is part of the gui module, QWidget is in a separate and now optional module (widgets) ○ Applications will typically use QWidget or QQuickView to create user interfaces ● It is possible to render directly to a QWindow with a QOpenGLContext ● QWindow can be embedded in a QWidget 6
  • 7. Qt’s OpenGL Support - QWindow ● Provides OpenGL and OpenGL ES Integration ○ QWindow supports rendering using (Desktop) OpenGL and OpenGL ES, depending on platform support ● Derive class from QWindow ○ In Constructor set QWindow's surface type: void QWindow::setSurfaceType(SurfaceType surfaceType) ○ Choose Format Attributes using QSurfaceFormat ■ OpenGL version and profile, sample buffer size, depth buffer size, etc.. ○ Create a QOpenGLContext to manage the native OpenGL context 7
  • 8. ● Create by calling QWindow::create() ● Implement a set of necessary functions ○ By convention: initializeGL(), updateGL(), resizeGL() ○ Needed to initialize and render OpenGL content ● Embed QWindow in a widget using QWidget:: createWindowContainer(...) returns a QWidget with the QWindow embedded inside it ● Additionally Qt has QOpenGLPaintDevice ○ Enables use of OpenGL accelerated QPainter rendering Qt’s OpenGL Support - QWindow 8
  • 9. Create OpenGL Context and Window OpenGLWindow::OpenGLWindow(QScreen * screen) : QWindow(screen) { setSurfaceType(OpenGLSurface); QSurfaceFormat requestedFormat; requestedFormat.setMajorVersion( 4 ); requestedFormat.setMinorVersion( 3 ); requestedFormat.setProfile(QSurfaceFormat::CoreProfile); requestedFormat.setSamples( 4 ); // for MSAA requestedFormat.setDepthBufferSize(24); m_context = new QOpenGLContext; m_context->setFormat( requestedFormat ); m_context->create(); setFormat( m_context->format() ); create(); } 9
  • 10. QOpenGLWindow ● Convenience subclass of QWindow to perform OpenGL painting ○ Enhanced QWindow that allows easily creating windows that perform OpenGL rendering ○ API compatible with QOpenGLWidget and similar to the legacy QGLWidget. ○ No dependency on widgets module and better performance. ○ Optionally backed by a framebuffer object ○ Default behavior (and thus performance) is equivalent to QWindow. 10
  • 11. Using QOpenGLWindow ● Subclass QOpenGLWindow and reimplement the following virtual functions: ○ initializeGL() to perform OpenGL resource initialization ○ resizeGL() to set up the transformation matrices and other window size dependent resources ○ paintGL() to issue OpenGL commands or draw using QPainter ● To schedule a repaint, call update() ○ Note that this will not immediately result in a call to paintGL(). ○ This is a slot so it can be connected to a QTimer:: timeout() signal to perform animation. 11
  • 12. QOpenGLWindow using QPainter ● QOpenGLWindow inherits QPaintDeviceWindow ● Allows opening a painter on itself and perform QPainter-based drawing: void paintGL() { QOpenGLFunctions *f = context()->functions(); f->glClear(GL_COLOR_BIT | GL_DEPTH_BUFFER_BIT); // issue some native OpenGL commands QPainter p(this); // draw using QPainter // animate continuously: schedule an update update(); } 12
  • 14. ● State machine that stores all data related to the OpenGL rendering state ○ Most OpenGL functions set or retrieve some state ○ Creating a window and an OpenGL context is not part of the OpenGL specification ● QOpenGLContext represents a native OpenGL context ○ Enables OpenGL rendering on a QSurface. ○ Context allow to share resources with other contexts with setShareContext() OpenGL Context 14
  • 15. QOpenGLContext To create: ● Create a QSurfaceFormat object ○ Set desired OpenGL version and profile ● Create the QOpenGLContext ○ Set the context format using the QSurfaceFormat object ● Finally call QOpenGLContext::create() ○ Use return value or isValid() to check if the context was successfully initialized ● Before using any OpenGL QOpenGLContext must be made current against a surface ○ QOpenGLContext::makeCurrent(QSurface*) 15
  • 16. ● When OpenGL rendering is done ○ Call swapBuffers() to swap the front and back buffers of the surface at the end of the update function ○ Newly rendered content becomes visible ○ QOpenGLContext requires to call makeCurrent() again before starting rendering a new frame, after calling swapBuffers() ● Use QOpenGLContext::format() to retrieve info on the context ○ Returns a QSurfaceFormat ○ OpenGL version, profile, etc... QOpenGLContext 16
  • 17. Qt’s OpenGL Support ● QOpenGLFunctions are convenience classes ● Simplify writing of OpenGL code ● Hide complexities of extension handling ● Hide differences between OpenGL ES 2 and desktop OpenGL ○ Allow the use of OpenGL ES 2 functions on Desktop OpenGL ○ No need to manually resolve OpenGL function pointers ○ Allowing cross-platform development of applications targeting mobile or embedded devices 17
  • 18. QAbstractOpenGLFunctions ● Family of classes that expose all functions for a given OpenGL version and profile ○ OpenGL implementations on different platforms are able to link to a variable number of OpenGL functions depending upon the OpenGL ABI on that platform ○ On many platforms most functions must be resolved at runtime, Options are: ■ Work with raw function pointers: QOpenGLContext::getProcAddress() ■ Use QOpenGLFunctions and only expose those functions common to OpenGL ES 2 and desktop OpenGL 18
  • 19. QAbstractOpenGLFunctions (cont.) ● Provides better support for newer versions of OpenGL (especially 3.0 and higher) ● Ease development of desktop applications relying on modern, desktop-only OpenGL features ● QOpenGLFunctions_X_Y_PROFILE ○ Core and Compatibility Profiles ○ Expose every core OpenGL function by way of a corresponding member function ○ Class for every valid combination of OpenGL version and profile following the naming convention: QOpenGLFunctions_<MAJOR VERSION>_<MINOR VERSION>[_PROFILE] 19
  • 20. ● Ensure QOpenGLContext is current before using it ● Call QOpenGLFunctions_X_Y_PROFILE::initializeOpenGLFunctions() once before using it to resolve function pointers Using QOpenGLFunctions_X_Y_PROFILE 20
  • 21. Qt’s OpenGL Support ● Classes that wrap native OpenGL Resources ○ QOpenGLBuffer, QOpenGLFramebufferObject QOpenGLShaderProgram, OpenGLTexture, QOpenGLVertexArrayObject ● Qt GUI Module Contains ○ QMatrix4x4, QVector4D and QQuaternion ○ Support common mathematical operations for 3D graphics ● Miscellaneous ○ Debugging, QOpenGLDebugLogger ○ Timing, QOpenGLTimeMonitor, QOpenGLTimerQuery 21
  • 22. QOpenGLDebugLogger QOpenGLDebugMessage QOpenGLTimeMonitor QOpenGLTimerQuery QOpenGLPaintDevice QOpenGLTexture (Qt 5.3) QOpenGLWidget(Qt 5.4) QOpenGLWindow(Qt 5.4) QOpenGLContext QOpenGLContextGroup QOpenGLVersionProfile QOpenGLFunctions* QOpenGLVertexArrayObject QOpenGLBuffer QOpenGLShader QOpenGLShaderProgram QOpenGLFrameBufferObject QOpenGLFrameBufferObjectFormat Qt 5 and OpenGL Classes 22
  • 23. ● Small program that runs on the GPU ● Ran as part of the OpenGL pipeline ● Programmable ● Coded in GLSL (OpenGL Shading Language) ● Makes rendering infinitely flexible What is a Shader? 23
  • 25. Shaders ● Two kinds of shaders: ○ Shaders that deal with Vertices, i.E: Vertex, Tessellation and Geometry shaders determine where on the screen a primitive is. ○ Fragment Shader uses that information to determine what color that fragment will be. ● Must have a version identifier at top of file ● Must have a main() function ● Each shader is compiled, then they are linked together to make a shader program ● Input/output interfaces must match, and are checked at link time 25
  • 26. ● Vertex Shader ○ Executed once for every vertex ○ Input: Content of Vertex Buffer Arrays and Uniforms ○ Output: Vertex position ● Fragment Shader ○ Executed once for every fragment ○ Input: Result of Rasterization after Vertex Shader ○ Output: Candidate pixel color (aka Fragment) Shader Basics 26
  • 27. ● Preparing Shaders ○ Compile vertex shader ○ Compile fragment shader ○ Configure attribute locations before linking ○ Link both shaders into a shader program ● Preparing shaders with Qt vs pure OpenGL ○ Much less code ○ Less error prone Prepare Shaders 27
  • 28. Example: Use Qt to Create Shader Program void OpenGLUtilities::createShaderProgram() { const GLubyte * _v=glGetString(GL_SHADING_LANGUAGE_VERSION); QByteArray _vstr; _vstr.append(_v[0]); _vstr.append(_v[2]); _vstr.append(_v[3]); int _vnumber=_vstr.toInt(); QByteArray version = "#version " + _vstr; bool isOpenGLES=(QOpenGLContext::openGLModuleType() == QOpenGLContext::LibGLES); if (_vnumber < 300) { version = isOpenGLES ? "#version 100" : "#version 120"; } version += "n"; QFile vtFile(":/vertex.vsh"); vtFile.open((QIODevice::ReadOnly | QIODevice::Text)); QFile fsFile (":/fragment.fsh"); fsFile.open((QIODevice::ReadOnly | QIODevice::Text)); if (!m_shaderProgram.addShaderFromSourceCode(QOpenGLShader::Vertex,version+vtFile.readAll())){ qDebug() << "Error in vertex shader:" << m_shaderProgram.log(); exit(1); } if (!m_shaderProgram.addShaderFromSourceCode(QOpenGLShader::Fragment,version+fsFile.readAll())) { qDebug() << "Error in fragment shader:" << m_shaderProgram.log(); exit(1); } if (_vnumber < 300) { m_shaderProgram.bindAttributeLocation("vertexPosition", 0); m_shaderProgram.bindAttributeLocation("vertexNormal", 1); } if ( !m_shaderProgram.link() ) { qDebug() << "Error linking shader program:" << m_shaderProgram.log(); exit(1); } }
  • 29. ● Create buffer object ● Bind the buffer, making it the active buffer ● Copy the data to the buffer // Triangle vertices float vertices[] = { -1.0f, -1.0f, 0.0f, 1.0f, -1.0f, 0.0f, 0.0f, 0.6f, 0.0f }; // Create a static buffer for vertex data m_vertexBuffer.create(); // Set usage pattern to Static Draw, (the data won't change) m_vertexBuffer.setUsagePattern( QOpenGLBuffer::StaticDraw ); // Bind the buffer to the current OpenGL context m_vertexBuffer.bind(); // Copy the data to the buffer m_vertexBuffer.allocate( vertices, 3 * 3 * sizeof( float ) ); Creating a VBO 29
  • 30. Vertex Attributes ● We have the data (in VBOs) ● We have the shaders compiled ● How do we map the data to the shader attributes? After compiling shaders before linking: m_shaderProgram.bindAttributeLocation("vertexPosition", 0); This assigns the attribute vertexPosition the first location (0) 30
  • 31. ● VBO data is mapped to shader attribute locations m_shaderProgram.bind(); m_vertexBuffer.bind(); int vertexLocation = m_shaderProgram.attributeLocation("vertexPosition"); m_shaderProgram.setAttributeBuffer( vertexLocation, // layout location GL_FLOAT, // data's type 0, // Offset to data in buffer 3); // number of components (3 for x,y,z) ○ Bind the shader program ○ Bind the VBO containing the attribute data ○ Enable the desired vertex attribute array location ○ Set the attribute buffer to desired attribute location, set number of components and stride ○ Supports VBOs with interleaved data Vertex Attribute Arrays 31
  • 32. Defining Uniform Values in Qt ● Yep, It is that simple! OpenGLShaderProgram has a myriad ways to do it, e.g.: m_shaderProgram. bind(); // Get the location of uniform value "uni" in the shader. int uniLocation = m_shaderProgram.uniformLocation("uni"); // Then update the value m_shaderProgram. setUniformValue(uniLocation,uniValue); // Or in one step m_shaderProgram.setUniformValue ("uni",0.8f,0.5f,0.5f); ● If the value changes during an animation this code would go in the updateGL function ● If it is static it could go into initializeGL after the shader program has been linked and bound 32
  • 33. Deprecated OpenGL Matrix Stack ● OpenGL Desktop version < 3 used to have “built in” matrix stacks and related functionality for dealing with transformations and projections ○ glRotate*, glTranslate*, glScale* ○ glMatrixMode(), glPushMatrix(), glPopMatrix() ○ glLoadIdentity() ○ glFrustum(), gluPerspective(...), gluLookAt(..) ● All of these are now deprecated and should/can no longer be used 33
  • 34. ● Fortunately, it is very easy to achieve the same functionality with more flexibility using Qt ● There are functions to: ○ Create or set a matrix to the identity matrix ■ Identity matrix is a diagonal matrix with all elements being 1. When multiplied with a vector the result will be the same vector. ○ Translate, Scale, Rotate ○ Create a (view) matrix representing a “camera” ○ Create perspective or orthographic projection matrix ● And then one can use QStack, QVector, QList and gain ultimate flexibility Matrices, Qt to the Rescue 34
  • 35. ● Contains convenient functions for handling Model, View, and Projection Matrices ○ QMatrix4x4::translate() ○ QMatrix4x4::scale() ○ QMatrix4x4::rotate() ○ QMatrix4x4::lookAt() ○ QMatrix4x4::perspective() ○ QMatrix4x4::ortho() QMatrix4x4 35
  • 36. ● Qt- 5.2 introduces QOpenGLTexture to encapsulate an OpenGL texture object ○ Makes it easy to work with OpenGL textures ○ Simplifies dealing with dependencies upon the capabilities of an OpenGL implementation ● Typical usage pattern for QOpenGLTexture is ○ Instantiate the object specifying the texture target type ○ Set properties that affect storage requirements e.g. storage format, dimensions ○ Allocate server-side storage ○ Optionally upload pixel data ○ Optionally set any additional properties e.g. filtering and border options ○ Render with texture or render to texture ○ In the common case of simply using a QImage as the source of texture pixel data most of the above steps are performed automatically. QOpenGLTexture 36
  • 37. ● Qt simplifies the process with: ○ QOpenGLFramebufferObject class ▪ Represents OpenGL FBO ▪ By default creates 2D texture for rendering target ▪ Function to return the OpenGL texture id ● Can be used for texture rendering ▪ Function to return rendered scene as a QImage ○ QOpenGLFramebufferObjectFormat() ▪ Specify format and attachments of FBO Qt Support for FBO 37
  • 38. Qt and OpenGL Extensions ● A list of all OpenGL extensions supported by the current context can be retrieved with a call to QSet<QByteArray> QOpenGLContext::​extensions() const The context or a sharing context must be current. ● Resolve the entry points if the extension introduces a new API: QOpenGLContext::getProcAddress(). ● QtOpenGLExtensions module contains a class for every OpenGL extension in the Khronos registry that introduces new API. 38
  • 39. OpenGL Debugging with Qt ● OpenGL programming can be error prone ○ Black screen syndrom. There is no indication what is going on? ○ To be sure that no errors are being returned from OpenGL implementation check glGetError after every API call ○ OpenGL errors stack up so need to use this in a loop. ○ Additional information e.g. performance issues, warnings about using deprecated APIs are not reported through the ordinary OpenGL error reporting mechanisms ● QOpenGLDebugLogger enables logging of OpenGL debugging messages ○ Provides access to the OpenGL debug log if OpenGL implementation supports it (by exposing the GL_KHR_debug extension) ○ Messages from the OpenGL server will either be logged in an internal OpenGL log or passed in "real-time", i.e. as they're generated from OpenGL, to listeners 39
  • 40. OpenGL Debugging with Qt ● Creating an OpenGL Debug Context ○ OpenGL implementations are allowed not to create any debug output at all, unless the OpenGL context is a debug context ○ Set QSurfaceFormat::DebugContext format option on the QSurfaceFormat used to create the QOpenGLContext object: format.setOption(QSurfaceFormat::DebugContext); ● Creating and Initializing a QOpenGLDebugLogger ○ QOpenGLDebugLogger is a simple QObject-derived class ○ Create an instance and initialize it before usage by calling initialize() with a current OpenGL context: QOpenGLContext *ctx = QOpenGLContext::currentContext(); QOpenGLDebugLogger *logger = new QOpenGLDebugLogger(this); logger->initialize(); ○ Note that GL_KHR_debug extension must be available in the context in order to access the messages logged by OpenGL ○ You can check the presence of this extension by calling: ctx->hasExtension(QByteArrayLiteral("GL_KHR_debug")) 40
  • 41. Qt OpenGL Debug Messages ● Reading the Internal OpenGL Debug Log ○ Messages stored in the internal log of debug messages can be retrieved by using the loggedMessages() function QList<QOpenGLDebugMessage> messages = logger->loggedMessages(); foreach (const QOpenGLDebugMessage &message, messages) qDebug() << message; ○ Internal log has limited size; Older messages will get discarded to make room for new incoming messages ● Real-time logging of messages ○ Receive a stream of debug messages from the OpenGL server as they are generated by the implementation ○ Connect a slot to the messageLogged() signal, and start logging by calling startLogging(): connect(logger, &QOpenGLDebugLogger::messageLogged, receiver, &LogHandler::handleLoggedMessage); logger->startLogging(); ● Similarly, logging can be disabled at any time by calling the stopLogging() function. 41
  • 42. ● Measure GPU execution time of OpenGL calls ● Use to profile an application’s rendering performance ● Timed results in nanoseconds ● Create and set number of samples that will be taken, e.g: m_timeMonitor = new QOpenGLTimeMonitor(this); m_timeMonitor->setSampleCount(3); if (!m_timeMonitor->create()) ...Handle error QOpenGLTimeMonitor 42
  • 43. ● QOpenGLTimeMonitor::recordSample() to record interval m_timeMonitor->recordSample(); glClear( GL_COLOR_BUFFER_BIT ); m_timeMonitor->recordSample(); glDrawArrays( GL_TRIANGLES, 0, 3 ); m_timeMonitor->recordSample(); QOpenGLTimeMonitor 43
  • 44. ● Call waitForSamples() or waitForIntervals() to retrieve samples or intervals (in nanoseconds) QVector<GLuint64> samples = m_timeMonitor->waitForSamples(); QVector<GLuint64> intervals = m_timeMonitor->waitForIntervals(); o These functions block until values are ready o Call isResultAvailable() to prevent blocking ● Reset to use again m_timeMonitor->reset(); QOpenGLTimeMonitor 44
  • 45. Conclusion ● Qt has many classes that make working with OpenGL much more efficient. ● Cross platform capabilities of Qt enhance the portability of OpenGL applications greatly. ● Developer efficiency translates directly to maintenance costs and time to market. ● Ideal for scientific applications, visualization and even some games.