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/*
* chess.c - part of the chess demo in the glut distribution.
*
* (C) Henk Kok (kok@wins.uva.nl)
*
* This file can be freely copied, changed, redistributed, etc. as long as
* this copyright notice stays intact.
*/
/*
* Marble texture - shamelessly ripped from siggraph92_C23.shar
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glut.h>
#include "chess.h"
#define DOT(a,b) (a[0] * b[0] + a[1] * b[1] + a[2] * b[2])
#define B 256
static int p[B + B + 2];
static GLfloat g[B + B + 2][3];
static int start = 1;
#define setup(i,b0,b1,r0,r1) \
t = vec[i] + 10000.; \
b0 = ((int)t) & (B-1); \
b1 = (b0+1) & (B-1); \
r0 = t - (int)t; \
r1 = r0 - 1.;
GLfloat noise3(GLfloat vec[3])
{
int bx0, bx1, by0, by1, bz0, bz1, b00, b10, b01, b11;
GLfloat rx0, rx1, ry0, ry1, rz0, rz1, *q, sx, sy, sz, a, b, c, d, t, u, v;
register int i, j;
if (start) {
start = 0;
init();
}
setup(0, bx0,bx1, rx0,rx1);
setup(1, by0,by1, ry0,ry1);
setup(2, bz0,bz1, rz0,rz1);
i = p[ bx0 ];
j = p[ bx1 ];
b00 = p[ i + by0 ];
b10 = p[ j + by0 ];
b01 = p[ i + by1 ];
b11 = p[ j + by1 ];
#define at(rx,ry,rz) ( rx * q[0] + ry * q[1] + rz * q[2] )
#define surve(t) ( t * t * (3. - 2. * t) )
#define lerp(t, a, b) ( a + t * (b - a) )
sx = surve(rx0);
sy = surve(ry0);
sz = surve(rz0);
q = g[ b00 + bz0 ] ; u = at(rx0,ry0,rz0);
q = g[ b10 + bz0 ] ; v = at(rx1,ry0,rz0);
a = lerp(sx, u, v);
q = g[ b01 + bz0 ] ; u = at(rx0,ry1,rz0);
q = g[ b11 + bz0 ] ; v = at(rx1,ry1,rz0);
b = lerp(sx, u, v);
c = lerp(sy, a, b); /* interpolate in y at lo x */
q = g[ b00 + bz1 ] ; u = at(rx0,ry0,rz1);
q = g[ b10 + bz1 ] ; v = at(rx1,ry0,rz1);
a = lerp(sx, u, v);
q = g[ b01 + bz1 ] ; u = at(rx0,ry1,rz1);
q = g[ b11 + bz1 ] ; v = at(rx1,ry1,rz1);
b = lerp(sx, u, v);
d = lerp(sy, a, b); /* interpolate in y at hi x */
return 1.5 * lerp(sz, c, d); /* interpolate in z */
}
void
init(void)
{
int i, j, k;
GLfloat v[3], s;
/* Create an array of random gradient vectors uniformly on the unit sphere */
srand(1);
for (i = 0 ; i < B ; i++) {
do { /* Choose uniformly in a cube */
for (j=0 ; j<3 ; j++)
v[j] = (GLfloat)((rand() % (B + B)) - B) / B;
s = DOT(v,v);
} while (s > 1.0); /* If not in sphere try again */
s = sqrt(s);
for (j = 0 ; j < 3 ; j++) /* Else normalize */
g[i][j] = v[j] / s;
}
/* Create a pseudorandom permutation of [1..B] */
for (i = 0 ; i < B ; i++)
p[i] = i;
for (i = B ; i > 0 ; i -= 2) {
k = p[i];
p[i] = p[j = rand() % B];
p[j] = k;
}
/* Extend g and p arrays to allow for faster indexing */
for (i = 0 ; i < B + 2 ; i++) {
p[B + i] = p[i];
for (j = 0 ; j < 3 ; j++)
g[B + i][j] = g[i][j];
}
}
GLfloat turbulence(GLfloat x, GLfloat y, GLfloat z, GLfloat lofreq, GLfloat hifreq)
{
GLfloat freq, t, p[3];
p[0] = x + 123.456;
p[1] = y;
p[2] = z;
t = 0;
for (freq = lofreq ; freq < hifreq ; freq *= 2.) {
t += fabs(noise3(p)) / freq;
p[0] *= 2.;
p[1] *= 2.;
p[2] *= 2.;
}
return t - 0.3; /* readjust to make mean value = 0.0 */
}
GLfloat marble(GLfloat x, GLfloat y, GLfloat z)
{
GLfloat m;
m = turbulence(x, y, z, 0.3, 400.0);
if (m > 1.0)
m = 1.0;
if (m < 0.0)
m = 0.0;
return m;
}
extern GLubyte white_square[TXSX][TXSY][3];
extern GLubyte black_square[TXSX][TXSY][3];
extern GLubyte wood[TXSX][TXSY][3];
void GenerateTextures(void)
{
int i,j,k;
GLfloat x,y,t,w,b;
for (i=0;i<TXSX;i++)
{
for (j=0;j<TXSY;j++)
{
x = ((GLfloat) i)/20.0;
y = ((GLfloat) j)/20.0;
t = marble(x, y, 0.0);
t = 0.2 + t;
if (t > 1.0)
t = 1.0;
wood[i][j][0] = (0.6*t)*255;
wood[i][j][1] = (0.4*t)*255;
wood[i][j][2] = (0.5-0.4*t)*255;
x = ((GLfloat) i)/20.0;
y = ((GLfloat) j)/20.0;
t = marble(x, y, 0.0);
t = 0.2 + t;
if (t > 1.0)
t = 1.0;
w = t;
b = 0.8 -t;
if (b < 0.0 )
b = 0.0;
for (k=0;k<3;k++)
{
white_square[i][j][k] = w*255;
black_square[i][TXSY-j][k] = b*255;
}
}
}
}
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