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perlin.c
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perlin.c
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// Pretty noise.
// (Perlin/Fractal noise)
#include <sys/types.h>
#include <nds/ndstypes.h>
#include <math.h>
#define fade(t) ((t) * (t) * (t) * ((t) * ((t) * 6 - 15) + 10))
#define lerp(t,a,b) ((a) + (t) * ((b) - (a)))
// One could copy this with a loop.
// One could also be fucklazy and copy it with copy-paste.
uint8_t p[512] = {
// Part 1
151,160,137,91,90,15,131,13,201,95,96,53,194,233,7,225,140,36,103,
30,69,142,8,99,37,240,21,10,23,190, 6,148,247,120,234,75,0,26,197,
62,94,252,219,203,117,35,11,32,57,177,33,88,237,149,56,87,174,20,
125,136,171,168, 68,175,74,165,71,134,139,48,27,166,77,146,158,231,
83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,
196,135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,
124,123,5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,
182,189,28,42,223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,
155,167, 43,172,9,129,22,39,253, 19,98,108,110,79,113,224,232,178,185,
112,104,218,246,97,228,251,34,242,193,238,210,144,12,191,179,162,241,
81,51,145,235,249,14,239,107,49,192,214, 31,181,199,106,157,184, 84,204,
176,115,121,50,45,127, 4,150,254,138,236,205,93,222,114,67,29,24,72,243,
141,128,195,78,66,215,61,156,180,
// Part 2
151,160,137,91,90,15,131,13,201,95,96,53,194,233,7,225,140,36,103,
30,69,142,8,99,37,240,21,10,23,190, 6,148,247,120,234,75,0,26,197,
62,94,252,219,203,117,35,11,32,57,177,33,88,237,149,56,87,174,20,
125,136,171,168, 68,175,74,165,71,134,139,48,27,166,77,146,158,231,
83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,
196,135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,
124,123,5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,
182,189,28,42,223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,
155,167, 43,172,9,129,22,39,253, 19,98,108,110,79,113,224,232,178,185,
112,104,218,246,97,228,251,34,242,193,238,210,144,12,191,179,162,241,
81,51,145,235,249,14,239,107,49,192,214, 31,181,199,106,157,184, 84,204,
176,115,121,50,45,127, 4,150,254,138,236,205,93,222,114,67,29,24,72,243,
141,128,195,78,66,215,61,156,180
};
float grad( int hash, float x, float y, float z ) {
int h = hash & 15;
float u = h<8 ? x : y;
float v = h<4 ? y : h == 12 || h == 14 ? x : z;
return( ((h & 1) == 0 ? u : -u ) + ((h & 2) == 0 ? v : -v) );
}
// This is a straight port of Perlins java reference implementation.
// It was ugly to begin with and now it is uglier thanks to me.
// Go me.
float noise_at( float x, float y, float z ) {
int X = ((int)x) & 255;
int Y = ((int)y) & 255;
int Z = ((int)z) & 255;
x -= (float)((int)x);
y -= (float)((int)y);
z -= (float)((int)z);
float u = fade(x);
float v = fade(y);
float w = fade(z);
int A = p[X ]+Y, AA = p[A]+Z, AB = p[A+1]+Z;
int B = p[X+1]+Y, BA = p[B]+Z, BB = p[B+1]+Z;
// Nesting go!
return(
lerp( w,
lerp( v,
lerp( u,
grad( p[AA ], x, y, z ),
grad( p[BA ], x-1, y, z )
),
lerp( u,
grad( p[AB ], x , y-1, z ),
grad( p[BB ], x-1, y-1, z )
)
),
lerp(v,
lerp(u,
grad( p[AA+1], x, y, z-1 ),
grad( p[BA+1], x-1, y, z-1 )
),
lerp(u,
grad(p[AB+1], x, y-1, z-1 ),
grad(p[BB+1], x-1, y-1, z-1 )
)
)
)
);
}