# Direct 3d 4th Vector

Hi,

I'm trying to parse an old valve .map file for educational purposes

Here is a cube...

( 0 64 64 ) ( 64 64 64 ) ( 64 0 64 ) 0 0 0 1 1.000000 1.000000
( 0 0 0 ) ( 64 0 0 ) ( 64 64 0 ) 0 0 0 1 1.000000 1.000000
( 0 64 64 ) ( 0 0 64 ) ( 0 0 0 ) 0 0 0 1 1.000000 1.000000
( 64 64 0 ) ( 64 0 0 ) ( 64 0 64 ) 0 0 0 1 1.000000 1.000000
( 64 64 64 ) ( 0 64 64 ) ( 0 64 0 ) 0 0 0 1 1.000000 1.000000
( 64 0 0 ) ( 0 0 0 ) ( 0 0 64 ) 0 0 0 1 1.000000 1.000000

Only three vectors are provided per face. Obviously, three points per face doesn't compose the complete square required. Each face of the cube is partial, having one triangle...

Is anyone able to provide me with the correct formula for determining the opposing vertices, completing the partial faces?

Help with this is much appreciated...

###### Who is Participating?

Graphics ExpertCommented:
Hi,

(   0 64 64 ) ( 64 64 64 )  ( 64   0 64 )  (   0   0 64 )  0 0 0 1 1.000000   1.000000
(   0   0   0 ) ( 64   0   0 )  ( 64 64   0 )  (   0 64   0 )  0 0 0 1 1.000000   1.000000
(   0 64 64 ) (   0   0 64 )  (   0   0   0 )  (   0 64   0 )  0 0 0 1 1.000000   1.000000
( 64 64   0 ) ( 64   0   0 )  ( 64   0 64 )  ( 64 64 64 )  0 0 0 1 1.000000   1.000000
( 64 64 64 ) (   0 64 64 )  (   0 64   0 )  ( 64 64   0 )  0 0 0 1 1.000000   1.000000
( 64   0   0 ) (   0   0   0 )  (   0   0 64 )  ( 64   0 64 )  0 0 0 1 1.000000   1.000000

Notice that in each line one of the tree coordinates ( x  y  z) are the same. For exemple, in line 1, all z's are 64, meaning the plane is at z=64. This is the cube's back face.
Line 2 is the front face, all z's are 0.
Line 3 is left face, all x's are 0.

Seems to be an incomplete information. For exemple, there is no number of vertices, number of edges, number of faces. Maybe the data always refers to polygons. It depends on the software you are using.

Actually the model (in this case, a cube) isn't calculated by formula, but by an algorithm instead. Hope now you watch a cube in your screen.

Jose
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Author Commented:
It turns out you're right!

Unforunately the algorithm is extremely complicated. It'll be many pages of code later before I can watch a cube.

Many thanks for pointing me in the right direction.
0
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