| /* |
| * Mesa 3-D graphics library |
| * Version: 6.5 |
| * |
| * Copyright (C) 2006 Brian Paul All Rights Reserved. |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a |
| * copy of this software and associated documentation files (the "Software"), |
| * to deal in the Software without restriction, including without limitation |
| * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
| * and/or sell copies of the Software, and to permit persons to whom the |
| * Software is furnished to do so, subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be included |
| * in all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS |
| * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN |
| * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
| * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
| */ |
| |
| /* |
| * SimplexNoise1234 |
| * Copyright (c) 2003-2005, Stefan Gustavson |
| * |
| * Contact: stegu@itn.liu.se |
| */ |
| |
| /** \file |
| \brief C implementation of Perlin Simplex Noise over 1,2,3, and 4 dimensions. |
| \author Stefan Gustavson (stegu@itn.liu.se) |
| */ |
| |
| /* |
| * This implementation is "Simplex Noise" as presented by |
| * Ken Perlin at a relatively obscure and not often cited course |
| * session "Real-Time Shading" at Siggraph 2001 (before real |
| * time shading actually took on), under the title "hardware noise". |
| * The 3D function is numerically equivalent to his Java reference |
| * code available in the PDF course notes, although I re-implemented |
| * it from scratch to get more readable code. The 1D, 2D and 4D cases |
| * were implemented from scratch by me from Ken Perlin's text. |
| * |
| * This file has no dependencies on any other file, not even its own |
| * header file. The header file is made for use by external code only. |
| */ |
| |
| |
| #include "main/imports.h" |
| #include "slang_library_noise.h" |
| |
| #define FASTFLOOR(x) ( ((x)>0) ? ((int)x) : (((int)x)-1) ) |
| |
| /* |
| * --------------------------------------------------------------------- |
| * Static data |
| */ |
| |
| /* |
| * Permutation table. This is just a random jumble of all numbers 0-255, |
| * repeated twice to avoid wrapping the index at 255 for each lookup. |
| * This needs to be exactly the same for all instances on all platforms, |
| * so it's easiest to just keep it as static explicit data. |
| * This also removes the need for any initialisation of this class. |
| * |
| * Note that making this an int[] instead of a char[] might make the |
| * code run faster on platforms with a high penalty for unaligned single |
| * byte addressing. Intel x86 is generally single-byte-friendly, but |
| * some other CPUs are faster with 4-aligned reads. |
| * However, a char[] is smaller, which avoids cache trashing, and that |
| * is probably the most important aspect on most architectures. |
| * This array is accessed a *lot* by the noise functions. |
| * A vector-valued noise over 3D accesses it 96 times, and a |
| * float-valued 4D noise 64 times. We want this to fit in the cache! |
| */ |
| unsigned char perm[512] = {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 |
| }; |
| |
| /* |
| * --------------------------------------------------------------------- |
| */ |
| |
| /* |
| * Helper functions to compute gradients-dot-residualvectors (1D to 4D) |
| * Note that these generate gradients of more than unit length. To make |
| * a close match with the value range of classic Perlin noise, the final |
| * noise values need to be rescaled to fit nicely within [-1,1]. |
| * (The simplex noise functions as such also have different scaling.) |
| * Note also that these noise functions are the most practical and useful |
| * signed version of Perlin noise. To return values according to the |
| * RenderMan specification from the SL noise() and pnoise() functions, |
| * the noise values need to be scaled and offset to [0,1], like this: |
| * float SLnoise = (SimplexNoise1234::noise(x,y,z) + 1.0) * 0.5; |
| */ |
| |
| static float grad1( int hash, float x ) { |
| int h = hash & 15; |
| float grad = 1.0f + (h & 7); /* Gradient value 1.0, 2.0, ..., 8.0 */ |
| if (h&8) grad = -grad; /* Set a random sign for the gradient */ |
| return ( grad * x ); /* Multiply the gradient with the distance */ |
| } |
| |
| static float grad2( int hash, float x, float y ) { |
| int h = hash & 7; /* Convert low 3 bits of hash code */ |
| float u = h<4 ? x : y; /* into 8 simple gradient directions, */ |
| float v = h<4 ? y : x; /* and compute the dot product with (x,y). */ |
| return ((h&1)? -u : u) + ((h&2)? -2.0f*v : 2.0f*v); |
| } |
| |
| static float grad3( int hash, float x, float y , float z ) { |
| int h = hash & 15; /* Convert low 4 bits of hash code into 12 simple */ |
| float u = h<8 ? x : y; /* gradient directions, and compute dot product. */ |
| float v = h<4 ? y : h==12||h==14 ? x : z; /* Fix repeats at h = 12 to 15 */ |
| return ((h&1)? -u : u) + ((h&2)? -v : v); |
| } |
| |
| static float grad4( int hash, float x, float y, float z, float t ) { |
| int h = hash & 31; /* Convert low 5 bits of hash code into 32 simple */ |
| float u = h<24 ? x : y; /* gradient directions, and compute dot product. */ |
| float v = h<16 ? y : z; |
| float w = h<8 ? z : t; |
| return ((h&1)? -u : u) + ((h&2)? -v : v) + ((h&4)? -w : w); |
| } |
| |
| /* A lookup table to traverse the simplex around a given point in 4D. */ |
| /* Details can be found where this table is used, in the 4D noise method. */ |
| /* TODO: This should not be required, backport it from Bill's GLSL code! */ |
| static unsigned char simplex[64][4] = { |
| {0,1,2,3},{0,1,3,2},{0,0,0,0},{0,2,3,1},{0,0,0,0},{0,0,0,0},{0,0,0,0},{1,2,3,0}, |
| {0,2,1,3},{0,0,0,0},{0,3,1,2},{0,3,2,1},{0,0,0,0},{0,0,0,0},{0,0,0,0},{1,3,2,0}, |
| {0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0}, |
| {1,2,0,3},{0,0,0,0},{1,3,0,2},{0,0,0,0},{0,0,0,0},{0,0,0,0},{2,3,0,1},{2,3,1,0}, |
| {1,0,2,3},{1,0,3,2},{0,0,0,0},{0,0,0,0},{0,0,0,0},{2,0,3,1},{0,0,0,0},{2,1,3,0}, |
| {0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0}, |
| {2,0,1,3},{0,0,0,0},{0,0,0,0},{0,0,0,0},{3,0,1,2},{3,0,2,1},{0,0,0,0},{3,1,2,0}, |
| {2,1,0,3},{0,0,0,0},{0,0,0,0},{0,0,0,0},{3,1,0,2},{0,0,0,0},{3,2,0,1},{3,2,1,0}}; |
| |
| /* 1D simplex noise */ |
| GLfloat _slang_library_noise1 (GLfloat x) |
| { |
| int i0 = FASTFLOOR(x); |
| int i1 = i0 + 1; |
| float x0 = x - i0; |
| float x1 = x0 - 1.0f; |
| float t1 = 1.0f - x1*x1; |
| float n0, n1; |
| |
| float t0 = 1.0f - x0*x0; |
| /* if(t0 < 0.0f) t0 = 0.0f; // this never happens for the 1D case */ |
| t0 *= t0; |
| n0 = t0 * t0 * grad1(perm[i0 & 0xff], x0); |
| |
| /* if(t1 < 0.0f) t1 = 0.0f; // this never happens for the 1D case */ |
| t1 *= t1; |
| n1 = t1 * t1 * grad1(perm[i1 & 0xff], x1); |
| /* The maximum value of this noise is 8*(3/4)^4 = 2.53125 */ |
| /* A factor of 0.395 would scale to fit exactly within [-1,1], but */ |
| /* we want to match PRMan's 1D noise, so we scale it down some more. */ |
| return 0.25f * (n0 + n1); |
| } |
| |
| /* 2D simplex noise */ |
| GLfloat _slang_library_noise2 (GLfloat x, GLfloat y) |
| { |
| #define F2 0.366025403f /* F2 = 0.5*(sqrt(3.0)-1.0) */ |
| #define G2 0.211324865f /* G2 = (3.0-Math.sqrt(3.0))/6.0 */ |
| |
| float n0, n1, n2; /* Noise contributions from the three corners */ |
| |
| /* Skew the input space to determine which simplex cell we're in */ |
| float s = (x+y)*F2; /* Hairy factor for 2D */ |
| float xs = x + s; |
| float ys = y + s; |
| int i = FASTFLOOR(xs); |
| int j = FASTFLOOR(ys); |
| |
| float t = (float)(i+j)*G2; |
| float X0 = i-t; /* Unskew the cell origin back to (x,y) space */ |
| float Y0 = j-t; |
| float x0 = x-X0; /* The x,y distances from the cell origin */ |
| float y0 = y-Y0; |
| |
| float x1, y1, x2, y2; |
| int ii, jj; |
| float t0, t1, t2; |
| |
| /* For the 2D case, the simplex shape is an equilateral triangle. */ |
| /* Determine which simplex we are in. */ |
| int i1, j1; /* Offsets for second (middle) corner of simplex in (i,j) coords */ |
| if(x0>y0) {i1=1; j1=0;} /* lower triangle, XY order: (0,0)->(1,0)->(1,1) */ |
| else {i1=0; j1=1;} /* upper triangle, YX order: (0,0)->(0,1)->(1,1) */ |
| |
| /* A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and */ |
| /* a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where */ |
| /* c = (3-sqrt(3))/6 */ |
| |
| x1 = x0 - i1 + G2; /* Offsets for middle corner in (x,y) unskewed coords */ |
| y1 = y0 - j1 + G2; |
| x2 = x0 - 1.0f + 2.0f * G2; /* Offsets for last corner in (x,y) unskewed coords */ |
| y2 = y0 - 1.0f + 2.0f * G2; |
| |
| /* Wrap the integer indices at 256, to avoid indexing perm[] out of bounds */ |
| ii = i % 256; |
| jj = j % 256; |
| |
| /* Calculate the contribution from the three corners */ |
| t0 = 0.5f - x0*x0-y0*y0; |
| if(t0 < 0.0f) n0 = 0.0f; |
| else { |
| t0 *= t0; |
| n0 = t0 * t0 * grad2(perm[ii+perm[jj]], x0, y0); |
| } |
| |
| t1 = 0.5f - x1*x1-y1*y1; |
| if(t1 < 0.0f) n1 = 0.0f; |
| else { |
| t1 *= t1; |
| n1 = t1 * t1 * grad2(perm[ii+i1+perm[jj+j1]], x1, y1); |
| } |
| |
| t2 = 0.5f - x2*x2-y2*y2; |
| if(t2 < 0.0f) n2 = 0.0f; |
| else { |
| t2 *= t2; |
| n2 = t2 * t2 * grad2(perm[ii+1+perm[jj+1]], x2, y2); |
| } |
| |
| /* Add contributions from each corner to get the final noise value. */ |
| /* The result is scaled to return values in the interval [-1,1]. */ |
| return 40.0f * (n0 + n1 + n2); /* TODO: The scale factor is preliminary! */ |
| } |
| |
| /* 3D simplex noise */ |
| GLfloat _slang_library_noise3 (GLfloat x, GLfloat y, GLfloat z) |
| { |
| /* Simple skewing factors for the 3D case */ |
| #define F3 0.333333333f |
| #define G3 0.166666667f |
| |
| float n0, n1, n2, n3; /* Noise contributions from the four corners */ |
| |
| /* Skew the input space to determine which simplex cell we're in */ |
| float s = (x+y+z)*F3; /* Very nice and simple skew factor for 3D */ |
| float xs = x+s; |
| float ys = y+s; |
| float zs = z+s; |
| int i = FASTFLOOR(xs); |
| int j = FASTFLOOR(ys); |
| int k = FASTFLOOR(zs); |
| |
| float t = (float)(i+j+k)*G3; |
| float X0 = i-t; /* Unskew the cell origin back to (x,y,z) space */ |
| float Y0 = j-t; |
| float Z0 = k-t; |
| float x0 = x-X0; /* The x,y,z distances from the cell origin */ |
| float y0 = y-Y0; |
| float z0 = z-Z0; |
| |
| float x1, y1, z1, x2, y2, z2, x3, y3, z3; |
| int ii, jj, kk; |
| float t0, t1, t2, t3; |
| |
| /* For the 3D case, the simplex shape is a slightly irregular tetrahedron. */ |
| /* Determine which simplex we are in. */ |
| int i1, j1, k1; /* Offsets for second corner of simplex in (i,j,k) coords */ |
| int i2, j2, k2; /* Offsets for third corner of simplex in (i,j,k) coords */ |
| |
| /* This code would benefit from a backport from the GLSL version! */ |
| if(x0>=y0) { |
| if(y0>=z0) |
| { i1=1; j1=0; k1=0; i2=1; j2=1; k2=0; } /* X Y Z order */ |
| else if(x0>=z0) { i1=1; j1=0; k1=0; i2=1; j2=0; k2=1; } /* X Z Y order */ |
| else { i1=0; j1=0; k1=1; i2=1; j2=0; k2=1; } /* Z X Y order */ |
| } |
| else { /* x0<y0 */ |
| if(y0<z0) { i1=0; j1=0; k1=1; i2=0; j2=1; k2=1; } /* Z Y X order */ |
| else if(x0<z0) { i1=0; j1=1; k1=0; i2=0; j2=1; k2=1; } /* Y Z X order */ |
| else { i1=0; j1=1; k1=0; i2=1; j2=1; k2=0; } /* Y X Z order */ |
| } |
| |
| /* A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z), */ |
| /* a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and */ |
| /* a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where */ |
| /* c = 1/6. */ |
| |
| x1 = x0 - i1 + G3; /* Offsets for second corner in (x,y,z) coords */ |
| y1 = y0 - j1 + G3; |
| z1 = z0 - k1 + G3; |
| x2 = x0 - i2 + 2.0f*G3; /* Offsets for third corner in (x,y,z) coords */ |
| y2 = y0 - j2 + 2.0f*G3; |
| z2 = z0 - k2 + 2.0f*G3; |
| x3 = x0 - 1.0f + 3.0f*G3; /* Offsets for last corner in (x,y,z) coords */ |
| y3 = y0 - 1.0f + 3.0f*G3; |
| z3 = z0 - 1.0f + 3.0f*G3; |
| |
| /* Wrap the integer indices at 256, to avoid indexing perm[] out of bounds */ |
| ii = i % 256; |
| jj = j % 256; |
| kk = k % 256; |
| |
| /* Calculate the contribution from the four corners */ |
| t0 = 0.6f - x0*x0 - y0*y0 - z0*z0; |
| if(t0 < 0.0f) n0 = 0.0f; |
| else { |
| t0 *= t0; |
| n0 = t0 * t0 * grad3(perm[ii+perm[jj+perm[kk]]], x0, y0, z0); |
| } |
| |
| t1 = 0.6f - x1*x1 - y1*y1 - z1*z1; |
| if(t1 < 0.0f) n1 = 0.0f; |
| else { |
| t1 *= t1; |
| n1 = t1 * t1 * grad3(perm[ii+i1+perm[jj+j1+perm[kk+k1]]], x1, y1, z1); |
| } |
| |
| t2 = 0.6f - x2*x2 - y2*y2 - z2*z2; |
| if(t2 < 0.0f) n2 = 0.0f; |
| else { |
| t2 *= t2; |
| n2 = t2 * t2 * grad3(perm[ii+i2+perm[jj+j2+perm[kk+k2]]], x2, y2, z2); |
| } |
| |
| t3 = 0.6f - x3*x3 - y3*y3 - z3*z3; |
| if(t3<0.0f) n3 = 0.0f; |
| else { |
| t3 *= t3; |
| n3 = t3 * t3 * grad3(perm[ii+1+perm[jj+1+perm[kk+1]]], x3, y3, z3); |
| } |
| |
| /* Add contributions from each corner to get the final noise value. */ |
| /* The result is scaled to stay just inside [-1,1] */ |
| return 32.0f * (n0 + n1 + n2 + n3); /* TODO: The scale factor is preliminary! */ |
| } |
| |
| /* 4D simplex noise */ |
| GLfloat _slang_library_noise4 (GLfloat x, GLfloat y, GLfloat z, GLfloat w) |
| { |
| /* The skewing and unskewing factors are hairy again for the 4D case */ |
| #define F4 0.309016994f /* F4 = (Math.sqrt(5.0)-1.0)/4.0 */ |
| #define G4 0.138196601f /* G4 = (5.0-Math.sqrt(5.0))/20.0 */ |
| |
| float n0, n1, n2, n3, n4; /* Noise contributions from the five corners */ |
| |
| /* Skew the (x,y,z,w) space to determine which cell of 24 simplices we're in */ |
| float s = (x + y + z + w) * F4; /* Factor for 4D skewing */ |
| float xs = x + s; |
| float ys = y + s; |
| float zs = z + s; |
| float ws = w + s; |
| int i = FASTFLOOR(xs); |
| int j = FASTFLOOR(ys); |
| int k = FASTFLOOR(zs); |
| int l = FASTFLOOR(ws); |
| |
| float t = (i + j + k + l) * G4; /* Factor for 4D unskewing */ |
| float X0 = i - t; /* Unskew the cell origin back to (x,y,z,w) space */ |
| float Y0 = j - t; |
| float Z0 = k - t; |
| float W0 = l - t; |
| |
| float x0 = x - X0; /* The x,y,z,w distances from the cell origin */ |
| float y0 = y - Y0; |
| float z0 = z - Z0; |
| float w0 = w - W0; |
| |
| /* For the 4D case, the simplex is a 4D shape I won't even try to describe. */ |
| /* To find out which of the 24 possible simplices we're in, we need to */ |
| /* determine the magnitude ordering of x0, y0, z0 and w0. */ |
| /* The method below is a good way of finding the ordering of x,y,z,w and */ |
| /* then find the correct traversal order for the simplex we're in. */ |
| /* First, six pair-wise comparisons are performed between each possible pair */ |
| /* of the four coordinates, and the results are used to add up binary bits */ |
| /* for an integer index. */ |
| int c1 = (x0 > y0) ? 32 : 0; |
| int c2 = (x0 > z0) ? 16 : 0; |
| int c3 = (y0 > z0) ? 8 : 0; |
| int c4 = (x0 > w0) ? 4 : 0; |
| int c5 = (y0 > w0) ? 2 : 0; |
| int c6 = (z0 > w0) ? 1 : 0; |
| int c = c1 + c2 + c3 + c4 + c5 + c6; |
| |
| int i1, j1, k1, l1; /* The integer offsets for the second simplex corner */ |
| int i2, j2, k2, l2; /* The integer offsets for the third simplex corner */ |
| int i3, j3, k3, l3; /* The integer offsets for the fourth simplex corner */ |
| |
| float x1, y1, z1, w1, x2, y2, z2, w2, x3, y3, z3, w3, x4, y4, z4, w4; |
| int ii, jj, kk, ll; |
| float t0, t1, t2, t3, t4; |
| |
| /* simplex[c] is a 4-vector with the numbers 0, 1, 2 and 3 in some order. */ |
| /* Many values of c will never occur, since e.g. x>y>z>w makes x<z, y<w and x<w */ |
| /* impossible. Only the 24 indices which have non-zero entries make any sense. */ |
| /* We use a thresholding to set the coordinates in turn from the largest magnitude. */ |
| /* The number 3 in the "simplex" array is at the position of the largest coordinate. */ |
| i1 = simplex[c][0]>=3 ? 1 : 0; |
| j1 = simplex[c][1]>=3 ? 1 : 0; |
| k1 = simplex[c][2]>=3 ? 1 : 0; |
| l1 = simplex[c][3]>=3 ? 1 : 0; |
| /* The number 2 in the "simplex" array is at the second largest coordinate. */ |
| i2 = simplex[c][0]>=2 ? 1 : 0; |
| j2 = simplex[c][1]>=2 ? 1 : 0; |
| k2 = simplex[c][2]>=2 ? 1 : 0; |
| l2 = simplex[c][3]>=2 ? 1 : 0; |
| /* The number 1 in the "simplex" array is at the second smallest coordinate. */ |
| i3 = simplex[c][0]>=1 ? 1 : 0; |
| j3 = simplex[c][1]>=1 ? 1 : 0; |
| k3 = simplex[c][2]>=1 ? 1 : 0; |
| l3 = simplex[c][3]>=1 ? 1 : 0; |
| /* The fifth corner has all coordinate offsets = 1, so no need to look that up. */ |
| |
| x1 = x0 - i1 + G4; /* Offsets for second corner in (x,y,z,w) coords */ |
| y1 = y0 - j1 + G4; |
| z1 = z0 - k1 + G4; |
| w1 = w0 - l1 + G4; |
| x2 = x0 - i2 + 2.0f*G4; /* Offsets for third corner in (x,y,z,w) coords */ |
| y2 = y0 - j2 + 2.0f*G4; |
| z2 = z0 - k2 + 2.0f*G4; |
| w2 = w0 - l2 + 2.0f*G4; |
| x3 = x0 - i3 + 3.0f*G4; /* Offsets for fourth corner in (x,y,z,w) coords */ |
| y3 = y0 - j3 + 3.0f*G4; |
| z3 = z0 - k3 + 3.0f*G4; |
| w3 = w0 - l3 + 3.0f*G4; |
| x4 = x0 - 1.0f + 4.0f*G4; /* Offsets for last corner in (x,y,z,w) coords */ |
| y4 = y0 - 1.0f + 4.0f*G4; |
| z4 = z0 - 1.0f + 4.0f*G4; |
| w4 = w0 - 1.0f + 4.0f*G4; |
| |
| /* Wrap the integer indices at 256, to avoid indexing perm[] out of bounds */ |
| ii = i % 256; |
| jj = j % 256; |
| kk = k % 256; |
| ll = l % 256; |
| |
| /* Calculate the contribution from the five corners */ |
| t0 = 0.6f - x0*x0 - y0*y0 - z0*z0 - w0*w0; |
| if(t0 < 0.0f) n0 = 0.0f; |
| else { |
| t0 *= t0; |
| n0 = t0 * t0 * grad4(perm[ii+perm[jj+perm[kk+perm[ll]]]], x0, y0, z0, w0); |
| } |
| |
| t1 = 0.6f - x1*x1 - y1*y1 - z1*z1 - w1*w1; |
| if(t1 < 0.0f) n1 = 0.0f; |
| else { |
| t1 *= t1; |
| n1 = t1 * t1 * grad4(perm[ii+i1+perm[jj+j1+perm[kk+k1+perm[ll+l1]]]], x1, y1, z1, w1); |
| } |
| |
| t2 = 0.6f - x2*x2 - y2*y2 - z2*z2 - w2*w2; |
| if(t2 < 0.0f) n2 = 0.0f; |
| else { |
| t2 *= t2; |
| n2 = t2 * t2 * grad4(perm[ii+i2+perm[jj+j2+perm[kk+k2+perm[ll+l2]]]], x2, y2, z2, w2); |
| } |
| |
| t3 = 0.6f - x3*x3 - y3*y3 - z3*z3 - w3*w3; |
| if(t3 < 0.0f) n3 = 0.0f; |
| else { |
| t3 *= t3; |
| n3 = t3 * t3 * grad4(perm[ii+i3+perm[jj+j3+perm[kk+k3+perm[ll+l3]]]], x3, y3, z3, w3); |
| } |
| |
| t4 = 0.6f - x4*x4 - y4*y4 - z4*z4 - w4*w4; |
| if(t4 < 0.0f) n4 = 0.0f; |
| else { |
| t4 *= t4; |
| n4 = t4 * t4 * grad4(perm[ii+1+perm[jj+1+perm[kk+1+perm[ll+1]]]], x4, y4, z4, w4); |
| } |
| |
| /* Sum up and scale the result to cover the range [-1,1] */ |
| return 27.0f * (n0 + n1 + n2 + n3 + n4); /* TODO: The scale factor is preliminary! */ |
| } |
| |
