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The OpenGL is a
graphics library which provides the interface to your graphics
hardware. It was first released by SGI systems. SGI is producer of
marvelous graphics workstations. They have been the king in the
graphics field. They released a line of graphics workstations and
server in the market. These workstations were loaded with IRIS/UNIX
operating system. They designed the powerful graphics library,
OpenGL, to exploit the power of the specialized proprietary graphics
hardware.
The best thing about the OpenGL is that it is hardware independent
library. It does not require any special hardware to perform its
functions. If your computer is equipped with special graphics
accelerator hardware, it will use it otherwise the required
functionality is emulated by software.
With the popularity and the power of the OpenGL, it becomes
mandatory to provide it on other operating systems platform. Now the
powerful OpenGL library is available on Windows platform also. It
comes free of cost with the Microsoft Visual C++ pack. The MSDN
supports the help files related to OpenGL. The OpenGL can be found
on your system at the following location if the Microsoft Visual C++
is installed on your system.
The include file path may be:
C:/Program Files/Microsoft Visual Studio/VC98/Include/GL
This contains three files
GL.h
GLAUX.h
GLU.h
Yes, believe me, just three include files, not more than that!!!
The library file path may be:
C:/Program Files/Microsoft Visual Studio/VC98/lib
It contains three OpenGL related libraries
GLAUX.lib
GLU32.lib
OPENGL32.lib
That’s it.
If you have such files on your system, you can start programming in
OpenGL. As I wrote earlier, OpenGL is a library, so you must include
the header file at appropriate places in your program like other
libraries and include OpenGL library during linking otherwise you
will get link time error messages.
Features of OpenGL
The following functionalities are provided by the OpenGL.
Drawing Primitive Geometric Objects
All the primitive drawing objects like line, polygon, triangle
strip, quad strip, triangle fan etc. are supported.
Viewing and Modeling Transformations
The orthographic , perspective projection, rotation, scaling,
translation etc. supported by the library.
Display Lists
To store a series of OpenGL Commands and execute at a later time. It
helps in building the animation, movies etc.
Color
Color and shading technique to describe the graphical model.
Lighting
Light model for ambient light, specular light, diffuse light
supported by the library.
Blending, Antialiasing, Fog
These features let you create a realistic computer generated scene.
Drawing Pixels, Bitmaps, Fonts, Images
Representation and display of 2D data as pixels, bitmaps or images.
Texture mapping
Mapping technique to wrap 1D or 2D texture on the 3D objects.
Framebuffer
Description and control of all the buffers. It helps in generation
of industry standard animations.
Evaluators & NURBS
Advanced technique for 2D-3D curves and surfaces.
Selection and Feedback
It allows the selection of 3D object on 3D screen using the mouse.
The OpenGL e-book can be searched on the Internet for free download.
If you could not find it please contact me for a free copy at
support@saturnsoftmills.com
So far, we have talked a lot about the OpenGL. Now it is time to
talk about its interface with the Visual C++. This is simple but
most important step before you start programming in OpenGL. The one
by one steps are given below, follow them and enjoy.
1. Create a New MFC based application (the way you wish).
2. Go to Project->.Setting. Click on the “link” tab. Specify the
name of all the OpenGL library in “Object/library Modules”. Press
OK.
3. Open your project view class cpp file. Search for the function
named “OnInitialUpdate”. If it is not found, go to view->ClassWizard
and add it. Add the following code inside the OnInitialUpdate
function.
void CYourPrjView::OnInitialUpdate()
{
CView::OnInitialUpdate();
// TODO: Add your specialized code here and/or call the base class
RECT rect;
cdc = (CDC*)GetDC();
// Getting the client rect
GetClientRect(&rect);
//setting pixel format for GL compatibility
PIXELFORMATDESCRIPTOR pfd = {
sizeof (PIXELFORMATDESCRIPTOR), // Size of this structure
1, // Version number
PFD_DRAW_TO_WINDOW | // Flags
PFD_SUPPORT_OPENGL |
PFD_DOUBLEBUFFER,
PFD_TYPE_RGBA, // RGBA pixel values
24, // 24-bit color
0, 0, 0, 0, 0, 0, // Don't care about these
0, 0, // No alpha buffer
0, 0, 0, 0, 0, // No accumulation buffer
32, // 32-bit depth buffer
0, // No stencil buffer
0, // No auxiliary buffers
PFD_MAIN_PLANE, // Layer type
0, // Reserved (must be 0)
0, 0, 0 // No layer masks
};
int nPixelFormat = ChoosePixelFormat(cdc->m_hDC, &pfd);
SetPixelFormat(cdc->m_hDC, nPixelFormat, &pfd);
hrc = wglCreateContext(cdc->m_hDC); // define hrc in your .h file
wglMakeCurrent(cdc->m_hDC,hrc);
// Setting the gl drawing environment
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0,1.0,1.0,2000.0);
glViewport(rect.left,rect.top,rect.right,rect.bottom);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glClearColor(0.0,0.0,0.0,1.0);
}
4. Declare the HGLRC hrc variable in the YourPrjView.h file.
5. Start programming in OpenGL, dude. Go and write some code in
OnDraw function, Compile, link and Run.
It is so simple to use OpenGL in Visual C++ environment. If you are
expert programmer and have good knowledge of OpenGL, you can produce
your own Jurassic Park. You can be next successful Producer and
Director in Hollywood. |
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