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Chris Brown
04-30-2001, 02:51 AM
I am currently having a problem with depth testing using OpenGL. The problem is as follows:
A file is read into my program containing vertex, face, normal, texture and color info.

A frustrum is applied using:

gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.0f,500.0f)

Depth testing is enabled as follows:

glClearDepth(1.0f);
glDepthFunc(GL_LEQUAL);
glEnable(GL_DEPTH_TEST);

Back face culling is applied:

glCullFace(GL_FRONT);
glEnable(GL_CULL_FACE);
glFrontFace(GL_CCW);


glClear is used to clear the depth buffer:
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

When the model is displayed iin the viewport, if the poly count is quite high, then the depth testing doesn't work.

I've proved that it's not a back face cull problem since if I do a sphere, the opposing face is culled and therefore eliminates the depth test problem. If I do a complex shape such as a torus knot or a full creature model, then the depth testing just doesn't work.

Any help would be appreciated.

Cheers,

Chris

Tom Nuydens
04-30-2001, 03:06 AM
Originally posted by Chris Brown:
gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.0f,500.0f)

The zNear value has to be > 0. Try something like [1, 500] instead of [0, 500].

- Tom

Chris Brown
04-30-2001, 03:39 AM
Thanks Tom, much appreciated.