Message-ID: <3ABDDBA9.B937780E@free.fr>
From: Kirill Pankratiev <kirill AT free DOT fr>
Organization: MICROWARE
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Newsgroups: comp.os.msdos.djgpp
Subject: please help with Texture coordinates!
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Date: Sun, 25 Mar 2001 11:52:22 GMT
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

Hello All!

I would like to know how to use texture coordinates for
perspective texture mapping.

So far i 've always used the 'magic vectors' to transform
points from screen space to texture space . ie

     (u,v) =  T * invP * invV *(Sx, Sy, 1)
  where invV is the inverse viewport transformation and invP
  is the inverse Projection and T is the "Magic matrix"
 Here we suppose that texture coordinates are
(0,0) (1,0)
(0,1) (1,1)

What i want to do is to have U V associated with each vertex
so that i can start at say (0,5,0.5) and end at (0.8, 0.8 ) of the
texture
 for exempla.
When i use linear interpolation it works but it gives very poor quality
because
it doesn' t take into account perspective deformation.
Can somebody please explain what i should do from the stage where i
project
the polygon?

Thanks.