[Sorry] Re: Re: [Update REQ 6003]: dithering

[daemon]

REQ 6003 is closed; must reopen it to assign someone.

... so the following mail message was not recorded:
From: Stuart Levy <slevy>
Date: Fri, 4 Oct 1996 18:30:03 -0500
Message-Id: <199610042330.SAA10251 at morse.geom.umn.edu>
To: software@geom.umn.edu
Subject: Re: [Update REQ 6003]: dithering

> We are trying to use Geomview with our finite element package.
> A common use will be to shade inside the elements in order to
> represent the varying quantities. Now I have a question :
> 
> Is it possible to creat a color map which goes from 0 to 1, such that
> 
>  at 0.0,   R=0, G=0, B=1  --> Blue
>  at 0.25   R=0, G=1, B=1  --> Light Blue
>  at 0.5    R=0, G=1, B=0  --> Green
>  at 0.75   R=1, G=1, B=0  --> Yellow
>  at 1.0    R=1, G=0, B=0  --> Red

Yes, I think so.  You can't easily have geomview apply this color map
itself, but if you can customize the conversion from your package's data
into geomview format, you can do this.

In the description of, say, OFF format (see "man 5 oogl"), note that you
can specify a four-component (R G B A) color for each vertex,
using a "COFF" object, as in

COFF
4 4 0		# 4 vertices, 4 faces

0 0 0   1 .5 0 1 # vertex at (0,0,0) colored orange
1 0 0   0 1 1 1  # vertex at (1,0,0) light blue
0 1 0   0 0 1 1  # vertex at (0,1,0) blue
0 0 1   .5 1 .5 1 # vertex at (0,0,1) light green

3  0 1 2
3  2 1 3
3  1 0 3
3  0 2 3

Try loading this file into geomview and selecting smooth shading.