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Editorial Team
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Asked: 2026-06-02T20:31:49+00:00

There have been many tutorials where each suggests using gluPerspective or glFrustum with a

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There have been many tutorials where each suggests using gluPerspective or glFrustum with a combination of other things, yet I’ve had difficulties setting up the right matrix. What code do I need to set up a 45˚ perspective view looking down the +z axis?

So far I have:

glShadeModel(GL_SMOOTH);
glClearColor(0,0,0,0);
glClearDepth(1);
glDepthFunc(GL_LEQUAL);
glViewport(0,0,width,height);
glEnable(GL_DEPTH_TEST);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45,1,0.1,100);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

But that doesn’t seem to work. All I get is a black screen when I attempt to draw things.

EDIT: Here’s the minimal drawing code:

glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glColor3ub(255,255,255);
glBegin(GL_TRIANGLE_STRIP);
 glVertex3f(20,20,20);
 glVertex3f(20,30,20);
 glVertex3f(30,20,20);
 glVertex3f(30,30,20);
glEnd();
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1 Answer

  1. Editorial Team

    EDIT: Here’s the minimal drawing code:

    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glColor3ub(255,255,255);
glBegin(GL_TRIANGLE_STRIP);
 glVertex3f(20,20,20);
 glVertex3f(20,30,20);
 glVertex3f(30,20,20);
 glVertex3f(30,30,20);
glEnd();

    Your vertex coordinates lie way outside the viewing volume. First, OpenGL by default “looks” down the negative Z axis, so your Z coordinates must be -100 < z < -0.1 for your choosen near and far clip plane.

    But even if you flipped the sign on the Z coordinate, your vertices still would lie outside the 45° FOV. (20, 0, 20) is 45° from the viewing axis, and (30, 0, 20) even farther. Try centering your vertex coodinates around (0,0,-5) like (+/-1, +/-1, -5)

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