gl_fog

OpenGL OpenGL: Advanced Coding
1

Hi…
I’m using GL_FOG in an 3d terrain engine, but it seem only to work in the Z axis…
That is, I have the desired fog effect in the Z axis, but when the camera rotates to the X axis, the fog effect gradually decrement…, then when I turn the camera to the Z axis, it works again
what happens? Any idea to solve it?

Thanks!!

2

A wild guess. Are you doing your rotation in the projection matrix? If so, shame on you, you should do it in the modelview matrix.

3

no,
now I’m using glLookAt()…

4

gluLookAt multiplies the CURRENT matrix with another one… Which matrix is current when you call it ???

Is it the PROJECTION_MATRIX or the MODELVIEW_MATRIX ???

If first case, then switch to the second !

Regards.

Eric

5

What is the terrain ?

Very large polygons ?

Some cards do not do per-pixel fog and only interpolate through the fog applied at each vertex. Rotating through 90 degrees could be badly affecting how this works.