cal/cal/fog.cal

{ RCSid $Id$ }
{
        BAD fog simulation effect using a converted z-file, eg:

        pvalue -r -df -b -h `getinfo -d < scene.pic` scene.z | \
                pcomb -e VIS:20 -f fog.cal scene.pic - > foggy.pic

        The constant VIS must be set to the visibility distance,
        ie. the distance at which half the contrast is lost.

        Substitute a local brightness model for fog_v to improve
        the effect.
}

dist = gi(2);                   { distance given by second file }

fog_v : .5;                     { fog particles are uniform grey }

prob = 1 - 2^-(dist/VIS);       { probability of intercepting fog particle }

fog(v) = prob*fog_v + (1-prob)*v;

ro = fog(ri(1));
go = fog(gi(1));
bo = fog(bi(1));
Revision:	1.2
Committed:	Wed Nov 21 18:10:45 2018 UTC (5 years, 6 months ago) by greg
Branch:	MAIN
CVS Tags:	rad5R4, rad5R3, HEAD
Changes since 1.1:	+1 -0 lines
Log Message:	Added missing RCSid tag
#	Content
1	{ RCSid $Id$ }
2	{
3	BAD fog simulation effect using a converted z-file, eg:
4
5	pvalue -r -df -b -h `getinfo -d < scene.pic` scene.z \| \
6	pcomb -e VIS:20 -f fog.cal scene.pic - > foggy.pic
7
8	The constant VIS must be set to the visibility distance,
9	ie. the distance at which half the contrast is lost.
10
11	Substitute a local brightness model for fog_v to improve
12	the effect.
13	}
14
15	dist = gi(2); { distance given by second file }
16
17	fog_v : .5; { fog particles are uniform grey }
18
19	prob = 1 - 2^-(dist/VIS); { probability of intercepting fog particle }
20
21	fog(v) = probfog_v + (1-prob)v;
22
23	ro = fog(ri(1));
24	go = fog(gi(1));
25	bo = fog(bi(1));