Odd Frustum problem...

[IgnusFast]

I have a program doing something like rainfall. I have frustum culling set up properly so that when an object leaves the screen (through any of the 6 screen planes) it is killed and a new one created.

The problem is that I just cannot seem to get the new objects to start just outside the screen! I though I could just use part of the culling code; I generate the Z coordinate, then I try to set the Y coordinate to just off screen. Instead, it's always just ON screen, so you see the new objects just pop up. Any suggestions?

I'm using float y = frustum[2][2] * t + frustum[2][3];, where t is the Z coordinate.

 

[rifter1818]

Just a guess....

Could it be that you need a clippper as until the object is fully on screen (without a clipper) it isnt shown so even though your object may start above the screen and move down it isnt visible until its on the screen, im not really sure on how to make a clipper, i think there might be a tutorial on it at www.directx4.net or www.directx4vb.com but im not sure... Hope this helps