I place the camera away from the origin along the z-axis, generate the cube objects at the origin with random x and y values, and move the cubes towards the viewer along the z-axis.

Naturally, the more cubes I have, the more calculations I have to perform. Therefore I would like to reset any cube as soon as it is outside the screen boundaries, so I can reuse it and restart it at the origin.

I have read lighthouse3d's excellent tutorial about view frustrum culling, but I believe there must be a more efficient way for my special case. The best I came up with was taking the center point of each cube [0,0,0], multiply it with the model-view-projection matrix (which is cheap, because I have that matrix already), transform its x and y values into device coordinates (dividing them by w) and see if either one is smaller than -1.0 or greater than 1.0.

This is quite effective, but of course the cubes disappear as soon as their

*center*is outside the screen boundaries, while I would like them to be completely outside before disappearing.