The Ring programming language version 1.7 book - Part 58 of 196

1. Ring Documentation, Release 1.7
You can add the source code (*.ring) and Images/Sound Files to the assets folder.
You will find the Flappy Bird 3000 Game ready for building.
The execution starts from the start.ring file
load "game2.ring"
56.3 Building the project
Move to the ring/android/ringlibsdl/project folder
We can build using the next command (We need to do this for one time only).
ndk-build
Then we can create the package (*.apk) using the next command.
56.3. Building the project 542

2. Ring Documentation, Release 1.7
ant debug
56.3. Building the project 543

3. CHAPTER
FIFTYSEVEN
USING RINGOPENGL AND RINGFREEGLUT FOR 3D GRAPHICS
In this chapter we will learn about using RingOpenGL
57.1 Samples Source (Authors)
The samples in this chapter are based on C Tutorials
from
1. http://www.lighthouse3d.com/tutorials/glut-tutorial/
2. http://www.wikihow.com/Make-a-Cube-in-OpenGL
57.2 What is RingOpenGL?
RingOpenGL contains the Ring binding to the OpenGL library
You can learn about OpenGL from : https://www.opengl.org/
RingOpenGL comes with support for the next versions
• OpenGL 1.1
• OpenGL 1.2
• OpenGL 1.3
• OpenGL 1.4
• OpenGL 1.5
• OpenGL 2.0
• OpenGL 2.1
• OpenGL 3.0
• OpenGL 3.2
• OpenGL 3.3
• OpenGL 4.0
• OpenGL 4.1
• OpenGL 4.2
• OpenGL 4.3
544

4. Ring Documentation, Release 1.7
• OpenGL 4.4
• OpenGL 4.5
• OpenGL 4.6
For example, if you want to use OpenGL 2.1 then load RingOpenGL 2.1 library
load "opengl21lib.ring"
57.3 What is RingFreeGLUT?
RingFreeGLUT contains the Ring binding to the FreeGLUT library
You can learn about FreeGLUT from : http://freeglut.sourceforge.net/
To use the RingFreeGLUT library, Just load the library
load "freeglut.ring"
57.4 The First Window using RingFreeGLUT
Example:
load "freeglut.ring"
func main
glutInit()
glutInitDisplayMode(GLUT_SINGLE)
glutInitWindowSize(800, 600)
glutInitWindowPosition(100, 10)
glutCreateWindow("RingFreeGLUT - Test 1")
glutDisplayFunc(:displayCode)
glutMainLoop()
func displaycode
Screen Shot
57.3. What is RingFreeGLUT? 545

5. Ring Documentation, Release 1.7
57.5 Drawing using RingOpenGL
Example:
load "freeglut.ring"
load "opengl21lib.ring"
func main
glutInit()
glutInitDisplayMode(GLUT_SINGLE)
glutInitWindowSize(800, 600)
glutInitWindowPosition(100, 10)
glutCreateWindow("RingFreeGLUT - Test 2")
glutDisplayFunc(:displayCode)
glutMainLoop()
func displaycode
glClear(GL_COLOR_BUFFER_BIT)
glColor3f(0,255,0)
glBegin(GL_POLYGON)
glVertex3f(0.0, 0.0, 0.0)
57.5. Drawing using RingOpenGL 546

6. Ring Documentation, Release 1.7
glVertex3f(0.5, 0.0, 0.0)
glVertex3f(0.5, 0.5, 0.0)
glVertex3f(0.0, 0.5, 0.0)
glEnd()
glColor3f(255,0,0)
glBegin(GL_POLYGON)
glVertex3f(0.0, 0.0, 0.0)
glVertex3f(0.5, 0.0, 0.0)
glVertex3f(-0.5,- 1, 0.0)
glVertex3f(0.0, -1, 0.0)
glEnd()
glColor3f(0,0,255)
glBegin(GL_POLYGON)
glVertex3f(0.0, 0.0, 0.0)
glVertex3f(-0.5, 0.0, 0.0)
glVertex3f(-0.5,- 0.5, 0.0)
glVertex3f(0.0, -0.5, 0.0)
glEnd()
glFlush()
Screen Shot
57.5. Drawing using RingOpenGL 547

7. Ring Documentation, Release 1.7
57.6 The First Triangle
Example:
load "freeglut.ring"
load "opengl21lib.ring"
func main
glutInit()
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA)
glutInitWindowSize(320,320)
glutInitWindowPosition(100, 10)
glutCreateWindow("RingFreeGLUT - Test 3")
glutDisplayFunc(:renderScene)
glutMainLoop()
func renderScene
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glBegin(GL_TRIANGLES)
glVertex3f(-0.5,-0.5,0.0)
glVertex3f(0.5,0.0,0.0)
glVertex3f(0.0,0.5,0.0)
glEnd()
glutSwapBuffers()
Screen Shot
57.6. The First Triangle 548

8. Ring Documentation, Release 1.7
57.7 Window Resize Event
Example:
load "freeglut.ring"
load "opengl21lib.ring"
func main
// init GLUT and create window
glutInit()
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA)
glutInitWindowPosition(100,100)
glutInitWindowSize(320,320)
glutCreateWindow("RingFreeGLUT - Test 4")
glutDisplayFunc(:renderScene)
glutReshapeFunc(:changeSize)
glutMainLoop()
func renderScene
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glBegin(GL_TRIANGLES)
glVertex3f(-2,-2,-5.0)
glVertex3f(2,0.0,-5.0)
glVertex3f(0.0,2,-5.0)
glEnd()
glutSwapBuffers()
func changesize
h = glutEventHeight()
w = glutEventWidth()
// Prevent a divide by zero, when window is too short
// (you cant make a window of zero width).
if (h = 0)
h = 1
ok
ratio = w * 1.0 / h
// Use the Projection Matrix
glMatrixMode(GL_PROJECTION)
// Reset Matrix
glLoadIdentity()
// Set the viewport to be the entire window
glViewport(0, 0, w, h)
// Set the correct perspective.
gluPerspective(45,ratio,1,100)
57.7. Window Resize Event 549

9. Ring Documentation, Release 1.7
// Get Back to the Modelview
glMatrixMode(GL_MODELVIEW)
57.8 Triangle Rotation
Example:
load "freeglut.ring"
load "opengl21lib.ring"
angle = 0
func main
// init GLUT and create window
glutInit()
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA)
glutInitWindowPosition(100,100)
glutInitWindowSize(320,320)
glutCreateWindow("RingFreeGLUT - Test 5")
glutDisplayFunc(:renderScene)
glutReshapeFunc(:changeSize)
glutIdleFunc(:renderScene)
glutMainLoop()
func renderScene
// Clear Color and Depth Buffers
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
// Reset transformations
glLoadIdentity()
// Set the camera
gluLookAt( 0.0, 0.0, 10.0,
0.0, 0.0, 0.0,
0.0, 1.0, 0.0)
glRotatef(angle, 0.0, 1.0, 0.0)
glBegin(GL_TRIANGLES)
glVertex3f(-2.0,-2.0, 0.0)
glVertex3f( 2.0, 0.0, 0.0)
glVertex3f( 0.0, 2.0, 0.0)
glEnd()
angle+=0.1
glutSwapBuffers();
func changesize
h = glutEventHeight()
w = glutEventWidth()
57.8. Triangle Rotation 550

10. Ring Documentation, Release 1.7
// Prevent a divide by zero, when window is too short
// (you cant make a window of zero width).
if (h = 0)
h = 1
ok
ratio = w * 1.0 / h
// Use the Projection Matrix
glMatrixMode(GL_PROJECTION)
// Reset Matrix
glLoadIdentity()
// Set the viewport to be the entire window
glViewport(0, 0, w, h)
// Set the correct perspective.
gluPerspective(45,ratio,1,100)
// Get Back to the Modelview
glMatrixMode(GL_MODELVIEW)
Screen Shot
57.9 Keyboard Events and Colors
Example:
load "freeglut.ring"
load "opengl21lib.ring"
57.9. Keyboard Events and Colors 551