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Resource Library: Graphics
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graphics-16000.iso
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msdos
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raytrace
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rayshade
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src
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mist.c
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C/C++ Source or Header
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1992-04-28
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2KB
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73 lines
/*
* mist.c
*
* Copyright (C) 1989, 1991, Craig E. Kolb
* All rights reserved.
*
* This software may be freely copied, modified, and redistributed
* provided that this copyright notice is preserved on all copies.
*
* You may not distribute this software, in whole or in part, as part of
* any commercial product without the express consent of the authors.
*
* There is no warranty or other guarantee of fitness of this software
* for any purpose. It is provided solely "as is".
*
* $Id: mist.c,v 4.0 91/07/17 14:40:42 kolb Exp Locker: kolb $
*
* $Log: mist.c,v $
* Revision 4.0 91/07/17 14:40:42 kolb
* Initial version.
*
*/
#include "atmosphere.h"
#include "mist.h"
Mist *
MistCreate(color, trans, zero, scale)
Color *color, *trans;
Float zero, scale;
{
Mist *mist;
mist = (Mist *)RayMalloc(sizeof(Mist));
mist->color = *color;
mist->trans = *trans;
mist->zero = zero;
mist->scale = 1. / scale;
return mist;
}
/*
* Add low-altitude mist to the given color.
*/
void
MistApply(mist, ray, pos, dist, color)
Mist *mist;
Ray *ray;
Vector *pos;
Float dist;
Color *color;
{
Float deltaZ, d, atten;
extern Float ExpAtten();
deltaZ = mist->scale * (pos->z - ray->pos.z);
if (fabs(deltaZ) > EPSILON)
d = (exp(-ray->pos.z*mist->scale + mist->zero) -
exp(-pos->z*mist->scale + mist->zero)) / deltaZ;
else
d = exp(-pos->z*mist->scale + mist->zero);
dist *= d;
atten = ExpAtten(dist, mist->trans.r);
color->r = atten*color->r + (1. - atten)*mist->color.r;
atten = ExpAtten(dist, mist->trans.g);
color->g = atten*color->g + (1. - atten)*mist->color.g;
atten = ExpAtten(dist, mist->trans.b);
color->b = atten*color->b + (1. - atten)*mist->color.b;
}