gistfile1.c

static void SetViewport(int x, int y, int w, int h, int outwidth, int outheight)
{
	float device_aspect = psglGetDeviceAspectRatio(psgl_device);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	GLfloat left = 0;
	GLfloat right = outwidth;
	GLfloat bottom = 0;
	GLfloat top = outheight;
	GLfloat zNear = -1.0;
	GLfloat zFar = 1.0;
	float desired_aspect = vidScrnAspect;
	GLuint lowerleft_x, lowerleft_y, viewport_width, viewport_height; 
	GLuint real_width = w, real_height = h;
	if(custom_aspect_ratio_mode)
	{
		lowerleft_x = x + nXOffset;
		lowerleft_y = y + nYOffset;
		real_width = w + nXScale;
		real_height = h + nYScale;
		left = x + nXOffset;
		right = y + nYOffset;
		bottom = gl_height + nYOffset;
	}
	else if ( (int)(device_aspect*1000) > (int)(desired_aspect*1000) )
	{
		float delta = (desired_aspect / device_aspect - 1.0) / 2.0 + 0.5;
		lowerleft_x = w * (0.5 - delta);
		lowerleft_y = 0;
		real_width = (2.0 * w * delta);
		real_height = h;
	}
	else if ( (int)(device_aspect*1000) < (int)(desired_aspect*1000) )
	{
		float delta = (device_aspect / desired_aspect - 1.0) / 2.0 + 0.5;
		lowerleft_x = 0;
		lowerleft_y = h * (0.5 - delta);
		real_width = w;
		real_height = (2.0 * h * delta);
	}
	else 
	{
		lowerleft_x = 0;
		lowerleft_y = 0;
		real_width = w;
		real_height = h;
	}
	glViewport(lowerleft_x, lowerleft_y, real_width, real_height);
	cg_viewport_width = real_width;
	cg_viewport_height = real_height;
	cgGLSetStateMatrixParameter(ModelViewProj_cgParam, CG_GL_MODELVIEW_PROJECTION_MATRIX, CG_GL_MATRIX_IDENTITY);
	glOrthof(left, right, bottom, top, zNear, zFar);
	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
	glClear(GL_COLOR_BUFFER_BIT);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
}