i am having a few issues with frustum culling with my app. i am rendering some terrain and i am breaking that terrain up into blocks,if a block is within the view frustum than i mark it visible if not than notvisisble. than when we render the terrain block's i only render those that are marked visible. This works and it does indeed cull away everything not in the viewing frustum BUT it does not work when i turn the camera with the mouse,i can see huge gpas where the blocks have been culled ...if i move the camera with the keyboard(forward or strafe) than it does update correctly. I am using frustum code from ultimategameprogramming and the camera class from the same place ....only difference is both the camera and frustum code is the older code before they changed there website ...it's the digiben one's! thanks for any help