The document discusses Hardware Abstraction Layer (HAL) and Component Object Model (COM) in Direct3D game programming. It explains that HAL provides hardware-accelerated graphics processing and supports both hardware and software vertex processing. COM provides inter-process communication, object creation across languages, and versioning to ensure backward compatibility. It also introduces common COM concepts like interfaces, IIDs, CLSIDs and the IUnknown interface.

1. Beginning Direct3D Game Programming:
2. Overview of HAL and COM
jintaeks@gmail.com
Division of Digital Contents, DongSeo University.
April 2016

2. HAL: Hardware Abstraction Layer
 In DirectX 8.0/9.0 games, you might choose between a HAL, a
pluggable software device, or a reference rasterizer; or the
application might select one automatically.
 You will find this device selection box, called the Direct3D
Settings dialog box, in every Direct3D example program
delivered with the DirectX 9.0 SDK.
2

3. 3

4.  The relationships among the Direct3D API, HAL, and
GDI(Graphics Device Interface) APIs.
 HAL is the primary device type, and it supports hardware-
accelerated rasterization and both hardware and software
vertex processing.
4

5. Device Name
 Use DxDiag to check device name.
5

6.  HAL is also able to emulate vertex processing in software
completely or in parts.
 The following flags control vertex-processing behavior for HAL
and reference devices:
– D3DCREATE_SOFTWARE_VERTEXPROCESSING
– D3DCREATE_HARDWARE_VERTEXPROCESSING
– D3DCREATE_MIXED_VERTEXPROCESSING
 Pure Device
– HAL is able to switch on a so-called pure device.
– This device uses a reduced number of state checks and is available
only if specific functions of the Direct3D API are not used.
– It is a bit faster than the non-pure hardware vertex-processing device.
6

7. Reference Rasterizer
 The reference device is supplied only with the installation of
the SDK.
 The reference rasterizer supports all Direct3D features. You
should only use it to test features that your card doesn’t
support.
 This device is optimized for accuracy, not for speed.
7

8. Controlling Devices
 You can configure all
controlling devices in the
DirectX Properties dialog box.
8

9. GPU-Z
 Use GPU-Z tool to measure
GPU memory.
9

10. Fraps
 Draw FPS on any DirectX surfaces of running process.
 Benchmark FPS of DirectX program.
10

11. Example: BasicHLSL
 Build and run BasicHLSL project in Sdk.
 Change device to reference rasterizer and check FPS using
Fraps.
11

12. COM: Component Object Model
 Component Object Model (COM) is a binary-
interface standard for software components introduced
by Microsoftin 1993.
 It is used to enable inter-process communication and
dynamic object creation in a large range of programming
languages.
 The essence of COM is a language-neutral way of
implementing objects that can be used in environments
different from the one in which they were created.
12

13. COM in DirectX
 COM provides a versioning strategy, which guarantees that all
games developed in earlier versions of DirectX are guaranteed
to run in future versions.
 It helps you encapsulate data and provides a consistent
interface to different languages.
13

14. Using COM for IPC
 Applications that use OLE manage compound documents—
that is, documents made up of data from a variety of different
applications.
 OLE provides services that make it easy for applications to call
on other applications for data editing.
 For example, a word processor that uses OLE could embed a
graph from a spreadsheet. The user could start the
spreadsheet automatically from within the word processor by
choosing the embedded chart for editing.
14

15. Technical details
 COM programmers build their software using COM-
aware components.
 Different component types are identified by class IDs (CLSIDs),
which are Globally Unique Identifiers (GUIDs).
 Each COM component exposes its functionality through one
or more interfaces.
 The different interfaces supported by a component are
distinguished from each other using interface IDs (IIDs), which
are GUIDs too.
15

16. IUnknown
 All COM components implement the IUnknown (custom)
interface, which exposes methods for reference
counting and type conversion (casting).
 A custom IUnknown interface consists of a pointer to a virtual
method table that contains a list of pointers to the functions
that implement the functions declared in the interface.
16

17. Classes
 A COM class (coclass) is a concrete implementation of one or
more interfaces, and closely resembles classes in object-
oriented programming languages. Classes are created based
on their class ID (CLSID) or based on their programmatic
identifier string (progid).
 Like many object-oriented languages, COM provides a
separation of interface from implementation.
17

18. Practice
class IUnknown {
public:
virtual void CreateInstance() = 0;
};
class KFirst : public IUnknown {
virtual void CreateInstance() {
printf( "Hello Firstrn" );
}
};
class KSecond : public IUnknown {
virtual void CreateInstance() {
printf( "Hello Secondrn" );
}
};
18

19. void main() {
IUnknown* pUnknown = nullptr;
KFirst first;
KSecond second;
pUnknown = &first;
pUnknown->CreateInstance();
pUnknown = &second;
pUnknown->CreateInstance();
}
19

20. References
 https://en.wikipedia.org/wiki/Component_Object_Model
 https://msdn.microsoft.com/ko-
kr/library/windows/desktop/aa365574(v=vs.85).aspx
20