glEnable(GL.GL_DEPTH_TEST) works rather funky

OpenGL Development JOGL Development
#1

I was under the impression that enabling GL.GL_DEPTH_TEST will result in coloring the pixels with regard to the color closest to us. Id est, if i put a gluSphere behind my xyz-axis i expect to see the axis IN FRONT of the sphere. As it is now, i get the sphere to shade the axis. So, i went on and enabled the depth testing but the result was no axis at all and a sphere looking like if it was sick in cancer and aids simultaneously.

Now, the question is - how to get rid of the cancer syndrome and get the axis back. Should one refrain from using quadrics? ???

#2

It should work as you describe.
Have you set the depth test function to something besides the default (glDepthFunc)?
Or the depth range (glDepthRange)?
Are you sure the model view transformation is correctly set for the desired result (i.e. is the camera actually positioned correctly?)
Maybe you’ve set the near z/far z range too large. This can cause z-buffer errors due to limited precision.
http://www.opengl.org/resources/faq/technical/depthbuffer.htm for some more ideas…

#3

It’s likely to be caused by a too large zFar, i’d say. I set mine to never miss a thing and that might be a little bit too large. I’ll give it a new try tomorrow and we’ll see what happens.

Thanks for the advice.