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#include "UnityPrefix.h"
#include "PerlinNoise.h"
inline static float fade(float t) { return t * t * t * (t * (t * 6 - 15) + 10); }
inline static float lerp(float t, float a, float b) { return a + t * (b - a); }
inline static float grad(int hash, float x, float y, float z) {
int h = hash & 15; // CONVERT LO 4 BITS OF HASH CODE
float u = h<8 ? x : y, // INTO 12 GRADIENT DIRECTIONS.
v = h<4 ? y : h==12||h==14 ? x : z;
return ((h&1) == 0 ? u : -u) + ((h&2) == 0 ? v : -v);
}
inline static float grad2(int hash, float x, float y) {
int h = hash & 15; // CONVERT LO 4 BITS OF HASH CODE
float u = h < 8 ? x : y, // INTO 12 GRADIENT DIRECTIONS.
v = h < 4 ? y : h==12 || h==14 ? x : 0;
return ((h&1) == 0 ? u : -u) + ((h&2) == 0 ? v : -v);
}
static int p[] =
{
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,
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 PerlinNoise::Noise(float x, float y) {
x = Abs(x);
y = Abs(y);
int floorX = int(x);
int floorY = int(y);
int X = floorX & 255; // FIND UNIT CUBE THAT
int Y = floorY & 255; // CONTAINS POINT.
x -= floorX; // FIND RELATIVE X,Y,Z
y -= floorY; // OF POINT IN CUBE.
float u = fade(std::min(x, 1.0f)); // COMPUTE FADE CURVES
float v = fade(std::min(y, 1.0f)); // FOR EACH OF X,Y,Z.
int A = p[X ]+Y, AA = p[A], AB = p[A+1], // HASH COORDINATES OF
B = p[X+1]+Y, BA = p[B], BB = p[B+1]; // THE 8 CUBE CORNERS,
float res = lerp(v, lerp(u, grad2(p[AA ], x , y ), // AND ADD
grad2(p[BA ], x-1, y )), // BLENDED
lerp(u, grad2(p[AB ], x , y-1 ), // RESULTS
grad2(p[BB ], x-1, y-1 )));// FROM 8
return res;
}
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