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/**
** sipp - SImple Polygon Processor
**
** A general 3d graphic package
**
** Copyright Equivalent Software HB 1992
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 1, or any later version.
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
** You can receive a copy of the GNU General Public License from the
** Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
**/
/**
** granite.c - Granite shader: using a 1/f fractal noise function for
** mixing color values.
**/
#include <math.h>
#include <stdio.h>
#include <sipp.h>
#include <noise.h>
#include <shaders.h>
#include <geometric.h>
extern bool noise_ready;
static void
granite (p, color, gd)
Vector *p;
Color *color;
Granite_desc *gd;
{
int i;
Vector v;
double temp, n = 0.5, freq = 1.0;
v = *p;
for (i = 0; i < 6 ; freq *= 2.0, i++) {
v.x *= 4.0 * freq;
v.y *= 4.0 * freq;
v.z *= 4.0 * freq;
temp = 0.5 * noise(&v);
/* temp = fabs(temp);*/
n += temp / freq;
}
color->red = gd->col1.red * n + gd->col2.red * (1.0 - n);
color->grn = gd->col1.grn * n + gd->col2.grn * (1.0 - n);
color->blu = gd->col1.blu * n + gd->col2.blu * (1.0 - n);
}
void
granite_shader(pos, normal, texture, view_vec, lights, gd, color, opacity)
Vector *pos;
Vector *normal;
Vector *texture;
Vector *view_vec;
Lightsource *lights;
Granite_desc *gd;
Color *color;
Color *opacity;
{
Vector tmp;
Surf_desc surface;
if (!noise_ready) {
noise_init();
}
VecScalMul(tmp, gd->scale, *texture);
granite(&tmp, &surface.color, gd);
surface.ambient = gd->ambient;
surface.specular = gd->specular;
surface.c3 = gd->c3;
surface.opacity = gd->opacity;
basic_shader(pos, normal, texture, view_vec, lights, &surface,
color, opacity);
}
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