| 1 | /*****************************************************************
|
|---|
| 2 |
|
|---|
| 3 | Implementation of the fractional Brownian motion algorithm. These
|
|---|
| 4 | functions were originally the work of F. Kenton Musgrave.
|
|---|
| 5 | For documentation of the different functions please refer to the
|
|---|
| 6 | book:
|
|---|
| 7 | "Texturing and modeling: a procedural approach"
|
|---|
| 8 | by David S. Ebert et. al.
|
|---|
| 9 |
|
|---|
| 10 | ******************************************************************/
|
|---|
| 11 |
|
|---|
| 12 | #if defined (_MSC_VER)
|
|---|
| 13 | #include <qglobal.h>
|
|---|
| 14 | #endif
|
|---|
| 15 |
|
|---|
| 16 | #include <time.h>
|
|---|
| 17 | #include <stdlib.h>
|
|---|
| 18 | #include "fbm.h"
|
|---|
| 19 |
|
|---|
| 20 | #if defined(Q_CC_MSVC)
|
|---|
| 21 | #pragma warning(disable:4244)
|
|---|
| 22 | #endif
|
|---|
| 23 |
|
|---|
| 24 | /* Definitions used by the noise2() functions */
|
|---|
| 25 |
|
|---|
| 26 | //#define B 0x100
|
|---|
| 27 | //#define BM 0xff
|
|---|
| 28 | #define B 0x20
|
|---|
| 29 | #define BM 0x1f
|
|---|
| 30 |
|
|---|
| 31 | #define N 0x1000
|
|---|
| 32 | #define NP 12 /* 2^N */
|
|---|
| 33 | #define NM 0xfff
|
|---|
| 34 |
|
|---|
| 35 | static int p[B + B + 2];
|
|---|
| 36 | static float g3[B + B + 2][3];
|
|---|
| 37 | static float g2[B + B + 2][2];
|
|---|
| 38 | static float g1[B + B + 2];
|
|---|
| 39 | static int start = 1;
|
|---|
| 40 |
|
|---|
| 41 | static void init(void);
|
|---|
| 42 |
|
|---|
| 43 | #define s_curve(t) ( t * t * (3. - 2. * t) )
|
|---|
| 44 |
|
|---|
| 45 | #define lerp(t, a, b) ( a + t * (b - a) )
|
|---|
| 46 |
|
|---|
| 47 | #define setup(i,b0,b1,r0,r1)\
|
|---|
| 48 | t = vec[i] + N;\
|
|---|
| 49 | b0 = ((int)t) & BM;\
|
|---|
| 50 | b1 = (b0+1) & BM;\
|
|---|
| 51 | r0 = t - (int)t;\
|
|---|
| 52 | r1 = r0 - 1.;
|
|---|
| 53 | #define at3(rx,ry,rz) ( rx * q[0] + ry * q[1] + rz * q[2] )
|
|---|
| 54 |
|
|---|
| 55 | /* Fractional Brownian Motion function */
|
|---|
| 56 |
|
|---|
| 57 | double fBm( Vector point, double H, double lacunarity, double octaves,
|
|---|
| 58 | int init )
|
|---|
| 59 | {
|
|---|
| 60 |
|
|---|
| 61 | double value, frequency, remainder;
|
|---|
| 62 | int i;
|
|---|
| 63 | static double exponent_array[10];
|
|---|
| 64 | float vec[3];
|
|---|
| 65 |
|
|---|
| 66 | /* precompute and store spectral weights */
|
|---|
| 67 | if ( init ) {
|
|---|
| 68 | start = 1;
|
|---|
| 69 | srand( time(0) );
|
|---|
| 70 | /* seize required memory for exponent_array */
|
|---|
| 71 | frequency = 1.0;
|
|---|
| 72 | for (i=0; i<=octaves; i++) {
|
|---|
| 73 | /* compute weight for each frequency */
|
|---|
| 74 | exponent_array[i] = pow( frequency, -H );
|
|---|
| 75 | frequency *= lacunarity;
|
|---|
| 76 | }
|
|---|
| 77 | }
|
|---|
| 78 |
|
|---|
| 79 | value = 0.0; /* initialize vars to proper values */
|
|---|
| 80 | frequency = 1.0;
|
|---|
| 81 | vec[0]=point.x;
|
|---|
| 82 | vec[1]=point.y;
|
|---|
|
|---|
