I am trying to rebuild the foundation of some OpenGL programming I lost a while ago. So I am trying to get a standard quad spinning. It shows up, but every time I run it, the aspect ratio changes WILDLY, from squashing or stretching to the quad being tiny or huge. I do nothing other than start it, shut it down, start it again, over and over, with completely different results every time.

This is the code I am dabbling with for the frustum. I know the frustum stuff is completely off, but I am interested in why it changes so wildly without me changing anything?

RECT rect;
GetWindowRect(hWnd, &rect);

……..

double width = rect->right - rect->left;
double height = rect->bottom - rect->top;
double aspect = width/height;

glViewport(0, 0, width, height);                    // Reset The Current Viewport
glMatrixMode(GL_PROJECTION);                        // Select The Projection Matrix
glLoadIdentity();                           // Reset The Projection Matrix

GLdouble fW, fH;

double t = 0.1 * tan(aspect*45/2);
double b = -t;
double r = aspect*t;
double l = -r;
glFrustum( l, r, b, t,0.1,100.0);

This is the drawing section. It is pretty much just copy paste:

        glClearColor (0.0f, 0.0f, 0.0f, 0.0f);
        glClear (GL_COLOR_BUFFER_BIT);

        glPushMatrix ();
        glRotatef (theta, 0.0f, 0.0f, 1.0f);
        glBegin (GL_QUADS);
        glColor3f (1.0f, 0.0f, 0.0f);   glVertex3f (-1.0f, -1.0f, -5.15f);
        glColor3f (1.0f, 1.0f, 0.0f);   glVertex3f (1.0f, -1.0f, -5.15f);
        glColor3f (1.0f, 0.0f, 1.0f);   glVertex3f (1.0f, 1.0f, -5.15f);
        glColor3f (0.0f, 1.0f, 0.0f);   glVertex3f (-1.0f, 1.0f, -5.15f);
        glEnd ();
        glPopMatrix ();

        SwapBuffers (hDC);

        theta += 1.0f;
        Sleep (1);