[Algorithms] Return of the front clip plane

[Jason Z. <zi...@n-...>]

Hi everyone, if you all remember our last episode "Attack of the Front Clip
Plane", we all learned that the further it is out the better zbuffer
accuracy you have.  Much was learned by most.  :)

Pushing my front clip out to 1 unit solved all of my zbuffer artifacts
nicely in the last game.  We are trying some new things for the new game and
running into a problem that was mostly glossed over in the prequel to this
email: collision and clipping of close-by objects.  Our game is first
person, and when you get within 1 unit of an object it will get clipped out.
This is obviously pretty nasty.  :)  I remember one solution to this
suggested was to dynamically move the front clip each frame depending on how
close objects are.

Another solution is to just make your player's bounding volume larger so you
can't get close enough to stuff to clip into it, this works okay but I find
that you have to keep the player from getting closer than 3 units with a 1
unit clip because of viewport rotation (just keeping the player 1 unit away
is fine if you are staring straight at a wall but as soon as you rotate the
edges of your viewport will clip it).

Anyone else have any other ideas?  Right now it looks like I might be going
the dynamic front clip route but I really don't want to, I have a feeling we
will be seeing lots of artifacts out in the wilderness because the player
will always be walking by a tree that they might not even be looking at.

For reference we use feet as units, with a front clip of 1 foot and a back
clip of 1000 feet.

Thanks,

- Jason Zisk
- nFusion Interactive LLC