Date: Sun, 25 Mar 2001 18:19:12 +0530 (IST)
From: Mridul Muralidharan <ec97027 AT matrix DOT reccal DOT ernet DOT in>
To: kirill AT free DOT fr
cc: Djgpp mailing list <djgpp AT delorie DOT com>
Subject: Re: please help with Texture coordinates!
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hi,
	check out allegro docs for info on perspective projection and
perspective corrected projection.allegro even supports them both. for more
info, get some book on 3d games/graphics programming (offhand - game
programming in C++ by ,De Gaus - spelling may be wrong ! )
anyway do not think this is the right newsgroup for this question .

hope this helped

Mridul Muralidharan
S8 Electronics and Communication
Regional Engineering College
Calicut
India

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On Sun, 25 Mar 2001, Kirill Pankratiev wrote:

> 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.
> 
>