mirror of
https://git.code.sf.net/p/quake/quakeforge
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110 lines
2.9 KiB
C
110 lines
2.9 KiB
C
#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <math.h>
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#include "QF/qtypes.h"
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#include "noise.h"
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// returns the 3D noise value for a point in space
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float
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noise3d (vec3_t v, int num)
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{
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int n;
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n = floor (v[0]) + floor (v[1]) * 57 + floor (v[2]) * 3251;
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n = (n << 13) ^ n;
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n = n * (n * n * 15731 + 789221) + 1376312589;
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return (n & 0x7fffffff) / 2147483648.0;
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}
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// a variation of Noise3D that takes 3 floats
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float
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noiseXYZ (float x, float y, float z, int num)
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{
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vec3_t v;
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v[0] = x;
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v[1] = y;
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v[2] = z;
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return noise3d (v, num);
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}
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// returns a noise value from a scaled up noise pattern
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//
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// Actually created by sampling points on a certain grid
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// and interpolating the inbetween value, making the noise smooth
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float
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noise_scaled (vec3_t v, float s, int num)
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{
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float n = 0;
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vec3_t a, b, c, d;
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a[0] = floor (v[0] / s) * s;
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b[0] = a[0] + s;
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c[0] = (v[0] - a[0]) / s;
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d[0] = 1 - c[0];
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a[1] = floor (v[1] / s) * s;
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b[1] = a[1] + s;
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c[1] = (v[1] - a[1]) / s;
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d[1] = 1 - c[1];
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a[2] = floor (v[2] / s) * s;
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b[2] = a[2] + s;
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c[2] = (v[2] - a[2]) / s;
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d[2] = 1 - c[2];
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n += noiseXYZ (a[0], a[1], a[2], num) * d[0] * d[1] * d[2];
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n += noiseXYZ (a[0], a[1], b[2], num) * d[0] * d[1] * c[2];
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n += noiseXYZ (a[0], b[1], a[2], num) * d[0] * c[1] * d[2];
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n += noiseXYZ (a[0], b[1], b[2], num) * d[0] * c[1] * c[2];
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n += noiseXYZ (b[0], a[1], a[2], num) * c[0] * d[1] * d[2];
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n += noiseXYZ (b[0], a[1], b[2], num) * c[0] * d[1] * c[2];
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n += noiseXYZ (b[0], b[1], a[2], num) * c[0] * c[1] * d[2];
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n += noiseXYZ (b[0], b[1], b[2], num) * c[0] * c[1] * c[2];
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return n;
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}
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// returns a Perlin noise value for a point in 3D space
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//
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// This noise function combines noise at several different scales
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// which makes it slower than just using one layer of noise
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float
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noise_perlin (vec3_t v, float p, int num)
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{
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float n = 0;
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n += noise_scaled (v, 1024, num);
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n += 0.5 + (noise_scaled (v, 256, num) - 0.5) * p;
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n += 0.5 + (noise_scaled (v, 64, num) - 0.5) * p * p;
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n += 0.5 + (noise_scaled (v, 16, num) - 0.5) * p * p * p;
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return n / 2 - 0.5;
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}
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// Use to create low-res noise patterns without interpolation
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// A good strategy for avoiding seams on terrain and curves
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// when called with a scale value of about 32
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//
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// This is because surfaces have some texture pixels which are
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// actually not in the polygon at all so their edges don't
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// perfectly fit together.
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//
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// Creates a random pattern of light and dark squares on flat
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// axis aligned surfaces, which is usually not what you want
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// but it may have interesting applications
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void
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snap_vector (vec3_t v_old, vec3_t v_new, float scale)
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{
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if (scale <= 0) {
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v_new[0] = v_old[0];
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v_new[1] = v_old[1];
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v_new[2] = v_old[2];
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} else {
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v_new[0] = floor (v_old[0] / scale + 0.5) * scale;
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v_new[1] = floor (v_old[1] / scale + 0.5) * scale;
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v_new[2] = floor (v_old[2] / scale + 0.5) * scale;
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}
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}
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