Original Post
So ive been messing with clipping planes lately (ogl) but have found they dont really do what i expect...i have a feeling this has to do with my lack of understanding of the correct way to specify the planes. given ax+by+cz+d < 0, to create a plane that clips everything with y value greater than or equal to 0, you'd use = <0,1,0,0> right? so y < 0, and there is no restriction placed upon x or z. This isnt the behaviour im getting tho, if you divide the screen into 2 triangles - top left, and bottom right, it is cutting off everything in the bottom right. I assume this is because i am using gluLookAt to position the world correctly and the clipping plane i specify is not being transformed through the new modelview matrix it creates? If this is the case, what is the usual approach of transforming the clipping plane values to produce the correct result? Should i use glMultMatrix with the clipping plane values after specifyign the initial transformation , and then extract the results and use those ? cheers, Scott