View Full Version : Depth test problem

02-19-2012, 03:16 AM
Im trying to draw a few things then switch to OrthoMode and draw a background. The problem is that the background hides the objects that I drew in normal mode.

I found someone having the same problem but that answer didnt help me.


"I think the values for z near and z far are in terms of the projection/camera's (which specifically is one of the things i'm not sure of) z axis.

Also, with a 3D projection (this might apply to ortho too, I can see no reason why it wouldn't in fact, but again, i'm not sure), you look down the negative Z axis, by default.

So, if the projection/camera's z axis has a negative Z component, and you're looking down the negative z axis, then a positive value of zfar is going to produce a negative vaule in world space coordinates, which, if your vertices are also in world space coordinates, will result in negative vertex z values being visible (all else being equal)."

I have depth test enabled in both modes. I dont use glRotate.
I do use glTranslate( 0, 0, -5) so the stuff i draw with 0.0 z coordinates will be visible, ...but the background has -100 z value so it shouldnt make any difference.

I switch to ortho with:
glOrtho(0.0, 1.0, 0.0, 1.0 / mouse->getAspectRatio(), 1.0, 500.0);

The "normal mode" was set up with:
gluPerspective(perspective_angle_vert, aspect_ratio, 0.1f, 200.0f);

02-19-2012, 06:13 AM
I am doing as follows for my skybox (drawn last):
glDepthRange(1, 1); // This will move the sky box to the far plane, exactly
glDepthFunc(GL_LEQUAL); // Seems to be needed, or depth value 1.0 will not be shown.

Maybe it can help you.

02-19-2012, 07:37 AM
Thanks! It worked(glDepthRange(1, 1)) except that Im doing parralax scrolling with more layers and now it draws them according to the drawing sequence.

("Seems to be needed" ...I like theese kind of comments:)