--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/demos/boxes/3rdparty/fbm.c Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,207 @@
+/*****************************************************************
+
+ Implementation of the fractional Brownian motion algorithm. These
+ functions were originally the work of F. Kenton Musgrave.
+ For documentation of the different functions please refer to the
+ book:
+ "Texturing and modeling: a procedural approach"
+ by David S. Ebert et. al.
+
+******************************************************************/
+
+#if defined (_MSC_VER)
+#include <qglobal.h>
+#endif
+
+#include <time.h>
+#include <stdlib.h>
+#include "fbm.h"
+
+#if defined(Q_CC_MSVC)
+#pragma warning(disable:4244)
+#endif
+
+/* Definitions used by the noise2() functions */
+
+//#define B 0x100
+//#define BM 0xff
+#define B 0x20
+#define BM 0x1f
+
+#define N 0x1000
+#define NP 12 /* 2^N */
+#define NM 0xfff
+
+static int p[B + B + 2];
+static float g3[B + B + 2][3];
+static float g2[B + B + 2][2];
+static float g1[B + B + 2];
+static int start = 1;
+
+static void init(void);
+
+#define s_curve(t) ( t * t * (3. - 2. * t) )
+
+#define lerp(t, a, b) ( a + t * (b - a) )
+
+#define setup(i,b0,b1,r0,r1)\
+ t = vec[i] + N;\
+ b0 = ((int)t) & BM;\
+ b1 = (b0+1) & BM;\
+ r0 = t - (int)t;\
+ r1 = r0 - 1.;
+#define at3(rx,ry,rz) ( rx * q[0] + ry * q[1] + rz * q[2] )
+
+/* Fractional Brownian Motion function */
+
+double fBm( Vector point, double H, double lacunarity, double octaves,
+ int init )
+{
+
+ double value, frequency, remainder;
+ int i;
+ static double exponent_array[10];
+ float vec[3];
+
+ /* precompute and store spectral weights */
+ if ( init ) {
+ start = 1;
+ srand( time(0) );
+ /* seize required memory for exponent_array */
+ frequency = 1.0;
+ for (i=0; i<=octaves; i++) {
+ /* compute weight for each frequency */
+ exponent_array[i] = pow( frequency, -H );
+ frequency *= lacunarity;
+ }
+ }
+
+ value = 0.0; /* initialize vars to proper values */
+ frequency = 1.0;
+ vec[0]=point.x;
+ vec[1]=point.y;
+ vec[2]=point.z;
+
+
+ /* inner loop of spectral construction */
+ for (i=0; i<octaves; i++) {
+ /* value += noise3( vec ) * exponent_array[i];*/
+ value += noise3( vec ) * exponent_array[i];
+ vec[0] *= lacunarity;
+ vec[1] *= lacunarity;
+ vec[2] *= lacunarity;
+ } /* for */
+
+ remainder = octaves - (int)octaves;
+ if ( remainder ) /* add in ``octaves'' remainder */
+ /* ``i'' and spatial freq. are preset in loop above */
+ value += remainder * noise3( vec ) * exponent_array[i];
+
+ return( value );
+
+} /* fBm() */
+
+
+float noise3(float vec[3])
+{
+ int bx0, bx1, by0, by1, bz0, bz1, b00, b10, b01, b11;
+ float rx0, rx1, ry0, ry1, rz0, rz1, *q, 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 ];
+
+ t = s_curve(rx0);
+ sy = s_curve(ry0);
+ sz = s_curve(rz0);
+
+
+ q = g3[ b00 + bz0 ] ; u = at3(rx0,ry0,rz0);
+ q = g3[ b10 + bz0 ] ; v = at3(rx1,ry0,rz0);
+ a = lerp(t, u, v);
+
+ q = g3[ b01 + bz0 ] ; u = at3(rx0,ry1,rz0);
+ q = g3[ b11 + bz0 ] ; v = at3(rx1,ry1,rz0);
+ b = lerp(t, u, v);
+
+ c = lerp(sy, a, b);
+
+ q = g3[ b00 + bz1 ] ; u = at3(rx0,ry0,rz1);
+ q = g3[ b10 + bz1 ] ; v = at3(rx1,ry0,rz1);
+ a = lerp(t, u, v);
+
+ q = g3[ b01 + bz1 ] ; u = at3(rx0,ry1,rz1);
+ q = g3[ b11 + bz1 ] ; v = at3(rx1,ry1,rz1);
+ b = lerp(t, u, v);
+
+ d = lerp(sy, a, b);
+
+ return lerp(sz, c, d);
+}
+
+static void normalize2(float v[2])
+{
+ float s;
+
+ s = sqrt(v[0] * v[0] + v[1] * v[1]);
+ v[0] = v[0] / s;
+ v[1] = v[1] / s;
+}
+
+static void normalize3(float v[3])
+{
+ float s;
+
+ s = sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);
+ v[0] = v[0] / s;
+ v[1] = v[1] / s;
+ v[2] = v[2] / s;
+}
+
+static void init(void)
+{
+ int i, j, k;
+
+ for (i = 0 ; i < B ; i++) {
+ p[i] = i;
+
+ g1[i] = (float)((rand() % (B + B)) - B) / B;
+
+ for (j = 0 ; j < 2 ; j++)
+ g2[i][j] = (float)((rand() % (B + B)) - B) / B;
+ normalize2(g2[i]);
+
+ for (j = 0 ; j < 3 ; j++)
+ g3[i][j] = (float)((rand() % (B + B)) - B) / B;
+ normalize3(g3[i]);
+ }
+
+ while (--i) {
+ k = p[i];
+ p[i] = p[j = rand() % B];
+ p[j] = k;
+ }
+
+ for (i = 0 ; i < B + 2 ; i++) {
+ p[B + i] = p[i];
+ g1[B + i] = g1[i];
+ for (j = 0 ; j < 2 ; j++)
+ g2[B + i][j] = g2[i][j];
+ for (j = 0 ; j < 3 ; j++)
+ g3[B + i][j] = g3[i][j];
+ }
+}