From:	"Elias Pschernig" <f DOT x DOT gruber-museum-arnsdorf AT magnet DOT at>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Allegro Texture Mapping
Date:	Mon, 27 Apr 1998 09:28:13 +0200
Organization:	magnet Internet Services
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Message-ID:	<6i2nmo$sk8$1@orudios.magnet.at>
References:	<1998042700340800 DOT UAA14329 AT ladder03 DOT news DOT aol DOT com>
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To:	djgpp AT delorie DOT com
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<1998042700340800 DOT UAA14329 AT ladder03 DOT news DOT aol DOT com>...wrote
>I'm just beginning to mess with Allegro 3d routines and am quite oblivious
to
>most 3d material.
>I've taken the example source ex25.c and modified it.
>I've given the array u and v values of zero, and loaded a 32x32 bitmap,
changed
>POLYTYPE_FLAT to POLYTYPE_ATEX, gotten rid of the c value, and changed NULL
to
>the bitmap name, and according to the documentation, this would map the
bitmap
>onto the squares.
>
>Instead, it takes the first pixel (upper left) of the bitmap and colors the
>squares accordingly, instead of mapping the entire bitmap onto each square.
>
>Can someone tell me what I'm missing? Is this too vauge? Here's the parts
of
>code I've changed...
>
>for(c=0;c<4;c++) {
>     v[c].u=1;
>     v[c].v=1;
>   }
>/* v[0].c = ((x + z) & 1) ? 2 : 3;*/
>
>quad3d_f(bmp, POLYTYPE_ATEX, textr, &v[0], &v[1], &v[2], &v[3]);
>
>(textr is the name of a 32x32 bitmap)
>
yea, the docs that came with allegro are not as good as allgro itself,
i had the same problem a week ago, and needed some time to figure
this out too. dont know how, but after an hour or so i found the mistake:

what you did is, you mapped only the pixel at (1,1) to your squares.
you need to set up the 4 vertices to 4 points inside you texture,
so instead of your for-loop you have to do:

v[0].u=0;v[0].v=0;
v[1].u=31;v[1].v=0;
v[2].u=31;v[2].v=31;
v[3].u=0;v[3].v=31;

happy ALLEGRO-programming,
Elias Pschernig

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