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Diffstat (limited to 'examples/demo/opengl/fbm.c')
| -rw-r--r-- | examples/demo/opengl/fbm.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/examples/demo/opengl/fbm.c b/examples/demo/opengl/fbm.c new file mode 100644 index 000000000..4409ae08f --- /dev/null +++ b/examples/demo/opengl/fbm.c @@ -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 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] ) + +static float noise3(float vec[3]); + +/* 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 retquired 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]; + } +} |