I'm going trough the Heightmap tutorial on gametutorials.com
, and I'm having problems with the fog coordinates.

I have defined them in my hedaer file:

but when i use it in my implementation file it doesnt show up

glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FOG_COORDINATE_EXT);

I've tried to comment the line, if i do i get fog everywhere.

(i also have scaled down the heightmap width this)

glScalef( 0.15f, 0.15f * HEIGHT_RATIO, 0.15f );

Dont #define them in your header, #include <OpenGL/glext.h> instead.