Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!rutgers!gatech!gitpyr!ccoprrm
From: ccoprrm@pyr.gatech.EDU (ROBERT E. MINSK)
Newsgroups: comp.graphics
Subject: Texture mapping
Keywords: Texture mapping, convex quadrilaterals, triangles
Message-ID: <9119@pyr.gatech.EDU>
Date: 6 Sep 89 03:50:27 GMT
Reply-To: ccoprrm@pyr.gatech.edu (ROBERT E. MINSK)
Organization: Georgia Institute of Technology
Lines: 24


  I am currently trying to add texture mapping to my ray tracer. The problem
I  am  having  is  texture  mapping  and  normal  interpolation  to  convex
quadrilaterals and triangles.  The situation is as follows:
  Given 4 points forming a convex planer quadrilateral,the texture verticies
associated with each point, and the intersection point on the quadrilateral,
find the associated (u,v) mapping coordinates for the intersection point.
For example:
  4 points       the associated texture vertices
  p1=(-5, 1, 2)  t1=(.2,.4)
  p2=(-2,-3, 6)  t2=(.4,.2)
  p3=( 2,-1, 4)  t3=(.8,.3)
  p4=( 1, 4,-1)  t4=(.7,.5)
intersection point = (-2,-1, 4)
find the (u,v) mapping coordinates

I assume a triangle will be the same mapping with two vertices sharing the
same points and mapping coordinates.
                                    Thanks in advance.
-- 
ROBERT E. MINSK
Georgia Insitute of Technology, Atlanta Georgia, 30332
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