Viewport problem in SIS card

OpenGL OpenGL: Basic Coding
1

I’m wondering why I see two viewports with SIS card.I don’t see such problem in NVidia and ATI cards.Here’s my reshape function:

   
void WINDOW::ReshapeGL(int width, int height)									// Reshape The Window When It's Moved Or Resized
{
	glViewport (0, 0, (GLsizei)(width), (GLsizei)(height));				// Reset The Current Viewport
	glMatrixMode (GL_PROJECTION);										// Select The Projection Matrix
	glLoadIdentity ();													// Reset The Projection Matrix
	gluPerspective( 45.0f, (float)width/(float)height, 0.1,  1000.0);
	glMatrixMode (GL_MODELVIEW);										// Select The Modelview Matrix
	glLoadIdentity ();													// Reset The Modelview Matrix
}

Our code reports that this cards has installed with Microsoft. Unfortunately we didin’t find its driver in the net to install it(I don’t remember the model of this SIS card). So does this viewport problem refer to my code?
-Ehsan-

2

Well, a slightly more robust ReshapeGL might check for a negative width or height (or division by zero), and ensure they are both within GL_MAX_VIEWPORT_DIMS.

3

So why don’t I see such a problem in NVidia and ATI cards?
-Ehsan-

4

“Our code reports that this cards has installed with Microsoft”

What does that mean?

You either are running using the MS implementation of GL or using SIS’s GL driver. Use glGetString(GL_VENDOR) and glGetString(GL_VERSION)

BTW, only nVidia and ATI produce quality drivers. Most others are not for 3D.