Subject: Collision Detection
From: Ted Stethem <[email-masked]>
To: [email-masked]
Date: Sat, 23 Mar 1996 20:16:48 -0800

This question isn't strictly about LW but since there are so many 
3D-knowledgeable people here, I thought I would give it a shot.
  I am interested in doing more scenes with characters and objects moving 
over uneven terrains, and while I have had moderate success with 
keyframes or just placing objects frame by frame, it is kind of tedious. 
And the results often occur where the character or object is suddenly in 
the air or partially buried.
  Is there some specific reason why object/surface collision detection is 
so hard to implement in 3D vs. 2D?  In video games, it is really trivial 
to detect collisions between sprites and backgrounds or other sprites.  I 
would think, from my limited programming skills, that since a surface 
exists in 3-dimensional coordinates and the object exists in 3d 
coordinates, that it would not be difficult to have a routine where a set 
of points coincides with another set of points.
  I notice most animators try to avoid close-ups with this type of 
situation (unless the surface is flat) by moving to shots of the upper 
torso or use long-distance shots where the lack of contact with the 
ground is not so noticeable.
  I suppose programs like Impact are there to deal with this but is there 
some reason why Lightwave doesn't have this capability built-in? Or is it 
there in the envelope map and I just haven't figured out how to use it?