86 lines
2 KiB
C++
86 lines
2 KiB
C++
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#include "noise.hpp"
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float mapfloat(float x, float in_min, float in_max, float out_min, float out_max)
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{
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return (float)(x - in_min) * (out_max - out_min) / (float)(in_max - in_min) + out_min;
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}
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//using the algorithm from http://freespace.virgin.net/hugo.elias/models/m_perlin.html
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// thanks to hugo elias
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float Noise2(float x, float y)
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{
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long noise;
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noise = x + y * 57;
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//noise = pow(noise << 13,noise);
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noise = (noise << 13)*noise;
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return ( 1.0 - ( long(noise * (noise * noise * 15731L + 789221L) + 1376312589L) & 0x7fffffff) / 1073741824.0);
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}
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float SmoothNoise2(float x, float y)
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{
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float corners, sides, center;
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corners = ( Noise2(x-1, y-1)+Noise2(x+1, y-1)+Noise2(x-1, y+1)+Noise2(x+1, y+1) ) / 16;
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sides = ( Noise2(x-1, y) +Noise2(x+1, y) +Noise2(x, y-1) +Noise2(x, y+1) ) / 8;
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center = Noise2(x, y) / 4;
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return (corners + sides + center);
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}
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float InterpolatedNoise2(float x, float y)
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{
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float v1,v2,v3,v4,i1,i2,fractionX,fractionY;
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long longX,longY;
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longX = long(x);
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fractionX = x - longX;
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longY = long(y);
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fractionY = y - longY;
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v1 = SmoothNoise2(longX, longY);
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v2 = SmoothNoise2(longX + 1, longY);
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v3 = SmoothNoise2(longX, longY + 1);
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v4 = SmoothNoise2(longX + 1, longY + 1);
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i1 = Interpolate(v1 , v2 , fractionX);
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i2 = Interpolate(v3 , v4 , fractionX);
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return(Interpolate(i1 , i2 , fractionY));
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}
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float Interpolate(float a, float b, float x)
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{
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//cosine interpolations
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return(CosineInterpolate(a, b, x));
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}
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float LinearInterpolate(float a, float b, float x)
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{
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return(a*(1-x) + b*x);
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}
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float CosineInterpolate(float a, float b, float x)
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{
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float ft = x * 3.1415927;
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float f = (1 - cos(ft)) * .5;
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return(a*(1-f) + b*f);
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}
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float PerlinNoise2(float x, float y, float persistance, int octaves)
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{
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float frequency, amplitude;
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float total = 0.0;
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for (int i = 0; i <= octaves - 1; i++)
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{
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frequency = pow(2,i);
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amplitude = pow(persistance,i);
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total = total + InterpolatedNoise2(x * frequency, y * frequency) * amplitude;
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}
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return(total);
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}
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