186 lines
3.5 KiB
C
186 lines
3.5 KiB
C
#include "noisesimplex.h"
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/*
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* Perlin noise implementation.
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*
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* Based on Ken Perlin implementation.
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*/
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#include <stdlib.h>
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#include <math.h>
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#include <string.h>
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#include <stdio.h>
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#define B 0x100
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#define BM 0xff
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#define N 0x1000
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#define NP 12 /* 2^N */
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#define NM 0xfff
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static int p[B + B + 2];
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static double g3[B + B + 2][3];
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static double g2[B + B + 2][2];
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static double g1[B + B + 2];
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#define s_curve(t) ( t * t * (3. - 2. * t) )
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#define lerp(t, a, b) ( a + t * (b - a) )
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#define setup(i,b0,b1,r0,r1)\
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t = vec[i] + N;\
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b0 = ((int)t) & BM;\
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b1 = (b0+1) & BM;\
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r0 = t - (int)t;\
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r1 = r0 - 1.;
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double noisePerlinGet1DValue(double x)
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{
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double vec[1] = {x*2.0};
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int bx0, bx1;
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double rx0, rx1, sx, t, u, v;
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setup(0, bx0,bx1, rx0,rx1);
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sx = s_curve(rx0);
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u = rx0 * g1[ p[ bx0 ] ];
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v = rx1 * g1[ p[ bx1 ] ];
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return lerp(sx, u, v) * 1.068 + 0.5;
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}
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double noisePerlinGet2DValue(double x, double y)
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{
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double vec[2] = {x*2.0, y*2.0};
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int bx0, bx1, by0, by1, b00, b10, b01, b11;
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double rx0, rx1, ry0, ry1, *q, sx, sy, a, b, t, u, v;
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int i, j;
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setup(0, bx0,bx1, rx0,rx1);
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setup(1, by0,by1, ry0,ry1);
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i = p[ bx0 ];
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j = p[ bx1 ];
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b00 = p[ i + by0 ];
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b10 = p[ j + by0 ];
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b01 = p[ i + by1 ];
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b11 = p[ j + by1 ];
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sx = s_curve(rx0);
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sy = s_curve(ry0);
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#define at2(rx,ry) ( rx * q[0] + ry * q[1] )
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q = g2[ b00 ] ; u = at2(rx0,ry0);
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q = g2[ b10 ] ; v = at2(rx1,ry0);
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a = lerp(sx, u, v);
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q = g2[ b01 ] ; u = at2(rx0,ry1);
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q = g2[ b11 ] ; v = at2(rx1,ry1);
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b = lerp(sx, u, v);
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return lerp(sy, a, b) * 0.709 + 0.5;
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}
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double noisePerlinGet3DValue(double x, double y, double z)
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{
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double vec[3] = {x*2.0, y*2.0, z*2.0};
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int bx0, bx1, by0, by1, bz0, bz1, b00, b10, b01, b11;
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double rx0, rx1, ry0, ry1, rz0, rz1, *q, sy, sz, a, b, c, d, t, u, v;
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int i, j;
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setup(0, bx0,bx1, rx0,rx1);
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setup(1, by0,by1, ry0,ry1);
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setup(2, bz0,bz1, rz0,rz1);
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i = p[ bx0 ];
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j = p[ bx1 ];
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b00 = p[ i + by0 ];
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b10 = p[ j + by0 ];
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b01 = p[ i + by1 ];
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b11 = p[ j + by1 ];
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t = s_curve(rx0);
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sy = s_curve(ry0);
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sz = s_curve(rz0);
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#define at3(rx,ry,rz) ( rx * q[0] + ry * q[1] + rz * q[2] )
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q = g3[ b00 + bz0 ] ; u = at3(rx0,ry0,rz0);
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q = g3[ b10 + bz0 ] ; v = at3(rx1,ry0,rz0);
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a = lerp(t, u, v);
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q = g3[ b01 + bz0 ] ; u = at3(rx0,ry1,rz0);
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q = g3[ b11 + bz0 ] ; v = at3(rx1,ry1,rz0);
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b = lerp(t, u, v);
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c = lerp(sy, a, b);
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q = g3[ b00 + bz1 ] ; u = at3(rx0,ry0,rz1);
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q = g3[ b10 + bz1 ] ; v = at3(rx1,ry0,rz1);
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a = lerp(t, u, v);
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q = g3[ b01 + bz1 ] ; u = at3(rx0,ry1,rz1);
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q = g3[ b11 + bz1 ] ; v = at3(rx1,ry1,rz1);
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b = lerp(t, u, v);
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d = lerp(sy, a, b);
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return lerp(sz, c, d) * 0.661 + 0.5;
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}
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static void _normalize2(double v[2])
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{
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double s;
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s = sqrt(v[0] * v[0] + v[1] * v[1]);
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v[0] = v[0] / s;
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v[1] = v[1] / s;
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}
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static void _normalize3(double v[3])
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{
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double s;
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s = sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);
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v[0] = v[0] / s;
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v[1] = v[1] / s;
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v[2] = v[2] / s;
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}
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void noisePerlinInit(void)
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{
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int i, j, k;
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for (i = 0 ; i < B ; i++) {
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p[i] = i;
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g1[i] = (double)((rand() % (B + B)) - B) / B;
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for (j = 0 ; j < 2 ; j++)
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g2[i][j] = (double)((rand() % (B + B)) - B) / B;
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_normalize2(g2[i]);
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for (j = 0 ; j < 3 ; j++)
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g3[i][j] = (double)((rand() % (B + B)) - B) / B;
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_normalize3(g3[i]);
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}
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while (--i) {
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k = p[i];
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p[i] = p[j = rand() % B];
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p[j] = k;
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}
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for (i = 0 ; i < B + 2 ; i++) {
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p[B + i] = p[i];
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g1[B + i] = g1[i];
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for (j = 0 ; j < 2 ; j++)
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g2[B + i][j] = g2[i][j];
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for (j = 0 ; j < 3 ; j++)
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g3[B + i][j] = g3[i][j];
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}
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}
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