From: Matthew Hesher (hesher++at++nu.cs.fsu.edu)
Date: 03/14/2000 10:33:41
pfUsers,
Here's a problem I'm having while attemping to learn Performer, so it's
almost a Performer question. I'm attemping to become versed in OpenGL at
the same time. I'm using,
glFrustum(-10.0, 10.0, -10.0, 10.0, 1.0, 20.0);
as my viewing Frustum (definition of clipping planes, right?) and
I seem to be getting a far clipping plane at z = -1. I determined
this by creating a polygon,
glXMakeCurrent(OnlyDisplay, *window1of5, *OnlyContext);
glMatrixMode(GL_MODELVIEW);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushMatrix();
glTranslatef(0, 0, -2);
glBegin(GL_POLYGON);
glColor3f(1,0,0);
glVertex3f(-1,0,0);
glColor3f(0,1,0);
glVertex3f(1,-1,0);
glColor3f(0,0,1);
glVertex3f(1,1,0);
glEnd();
glPopMatrix();
glXSwapBuffers(OnlyDisplay, *window1of5);
and when I translate the MODELVIEW matrix more than 1 unit away from me (-1)
down the z axis it disappears. I've tried makeing a polygon as follows,
glBegin(GL_POLYGON);
glColor3f(1,0,0);
glVertex3f(-1,0,-15);
glColor3f(0,1,0);
glVertex3f(1,-1,0);
glColor3f(0,0,1);
glVertex3f(1,1,0);
glEnd();
and the polygon gets chopped in two (the only visible part is a sliver (10ish
pixels wide) on the right side of my window.) Can anyone suggest what I might
be overlooking here?
Curt Hesher
hesher++at++cs.fsu.edu
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