RE: [Algorithms] splat an area through a world

[Brian S. <Brian.Smith@RealPage.com>]

Sorry about a "me too" message, but I would like to hear any opinions on the
subject as well.  Good question.

Well, I did have an idea or two pop into my head.  Considering individual
segments of the extruded shape's path (ie, the extrusion portion from one
path-node to it's neighbor), you could just do bounding-volume collision
testing (such as testing the shape-segment planes against local world
geometry vertices).  The BV used could very well be the shape itself.
Though calculating precise penetration amounts doesn't sound like much fun.

Another idea.  Build a silhouette of the shape-segment, using an eyepoint
created from the starting pathnode looking at the neighbor node.  I'm not
familiar with the stencil buffer (or, really, rendering-specific stuff in
general), but perhaps you could do a quasi render with depth or stencil
checking to see what percentage of the silhouette gets filled in.  Sounds
slow, but I'm clueless.

Being quite the non-guru (anti-guru?) in these matters, I'm sure there's
plenty of holes to be punched in those ideas. :-)

/Brian

-----Original Message-----
From: Corrinne Yu [mailto:cor...@ho...] 
Sent: Thursday, May 31, 2001 5:45 PM
To: gda...@li...
Subject: [Algorithms] splat an area through a world


1. I have an area, a shape.
2. I want to extrude this area along a line of motion through a sorted
world. 3. I don't want my shape-line motion to be stopped if only 1 point,
or 1 part of the shape is stopped. I want it to stop only if and when every
pixel of the entire shape is blocked by something. 4. I want to know that if
any part of this shape area is capable of reaching its final destination
unblocked, to return TRUE. That to returns FALSE only if not a single pixel
of this area can reach its destination.

How do you go about implementing this conditional test?

Corrinne Yu


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