commit 89eae2d3472d29694a21d4be8e60f7ef1c370403
parent 8830a7671f08db7247fbac950483ff40207fc3fb
Author: Brian Swetland <swetland@frotz.net>
Date: Tue, 29 Jan 2013 20:38:22 -0800
util: add Stefan Gustavson's SimplexNoise1234
Diffstat:
| A | simplexnoise.cc | | | 484 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
| M | util.h | | | 6 | ++++++ |
2 files changed, 490 insertions(+), 0 deletions(-)
diff --git a/simplexnoise.cc b/simplexnoise.cc
@@ -0,0 +1,484 @@
+/* SimplexNoise1234, Simplex noise with true analytic derivative in 1D to 4D.
+ *
+ * Author: Stefan Gustavson, 2003-2005
+ * Contact: stegu@itn.liu.se
+ *
+ * This code was GPL licensed until February 2011. As the original
+ * author of this code, I hereby release it irrevocably into the public
+ * domain. Please feel free to use it for whatever you want. Credit
+ * is appreciated where appropriate, and I also appreciate being told
+ * where this code finds any use, but you may do as you like.
+ * Alternatively, if you want to have a familiar OSI-approved license,
+ * you may use This code under the terms of the MIT license:
+ *
+ * Copyright (C) 2003-2005 by Stefan Gustavson. All rights reserved.
+ * This code is licensed to you under the terms of the MIT license:
+ *
+ * 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 THE AUTHORS OR COPYRIGHT HOLDERS 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.
+ *
+ */
+
+/*
+ * 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.
+ */
+
+#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!
+ */
+static 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 = (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
+float snoise(float x) {
+
+ int i0 = FASTFLOOR(x);
+ int i1 = i0 + 1;
+ float x0 = x - i0;
+ float x1 = x0 - 1.0f;
+
+ 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);
+
+ float t1 = 1.0f - x1*x1;
+// 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
+float snoise(float x, float y) {
+
+#define F2 0.366025403 // F2 = 0.5*(sqrt(3.0)-1.0)
+#define G2 0.211324865 // 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;
+
+ // 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
+
+ float x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords
+ float y1 = y0 - j1 + G2;
+ float x2 = x0 - 1.0f + 2.0f * G2; // Offsets for last corner in (x,y) unskewed coords
+ float y2 = y0 - 1.0f + 2.0f * G2;
+
+ // Wrap the integer indices at 256, to avoid indexing perm[] out of bounds
+ int ii = i & 0xff;
+ int jj = j & 0xff;
+
+ // Calculate the contribution from the three corners
+ float 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);
+ }
+
+ float 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);
+ }
+
+ float 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
+float snoise(float x, float y, float z) {
+
+// Simple skewing factors for the 3D case
+#define F3 0.333333333
+#define G3 0.166666667
+
+ 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;
+
+ // 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.
+
+ float x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
+ float y1 = y0 - j1 + G3;
+ float z1 = z0 - k1 + G3;
+ float x2 = x0 - i2 + 2.0f*G3; // Offsets for third corner in (x,y,z) coords
+ float y2 = y0 - j2 + 2.0f*G3;
+ float z2 = z0 - k2 + 2.0f*G3;
+ float x3 = x0 - 1.0f + 3.0f*G3; // Offsets for last corner in (x,y,z) coords
+ float y3 = y0 - 1.0f + 3.0f*G3;
+ float z3 = z0 - 1.0f + 3.0f*G3;
+
+ // Wrap the integer indices at 256, to avoid indexing perm[] out of bounds
+ int ii = i & 0xff;
+ int jj = j & 0xff;
+ int kk = k & 0xff;
+
+ // Calculate the contribution from the four corners
+ float 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);
+ }
+
+ float 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);
+ }
+
+ float 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);
+ }
+
+ float 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
+float snoise(float x, float y, float z, float w) {
+
+ // The skewing and unskewing factors are hairy again for the 4D case
+#define F4 0.309016994 // F4 = (Math.sqrt(5.0)-1.0)/4.0
+#define G4 0.138196601 // 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
+
+ // 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.
+
+ float x1 = x0 - i1 + G4; // Offsets for second corner in (x,y,z,w) coords
+ float y1 = y0 - j1 + G4;
+ float z1 = z0 - k1 + G4;
+ float w1 = w0 - l1 + G4;
+ float x2 = x0 - i2 + 2.0f*G4; // Offsets for third corner in (x,y,z,w) coords
+ float y2 = y0 - j2 + 2.0f*G4;
+ float z2 = z0 - k2 + 2.0f*G4;
+ float w2 = w0 - l2 + 2.0f*G4;
+ float x3 = x0 - i3 + 3.0f*G4; // Offsets for fourth corner in (x,y,z,w) coords
+ float y3 = y0 - j3 + 3.0f*G4;
+ float z3 = z0 - k3 + 3.0f*G4;
+ float w3 = w0 - l3 + 3.0f*G4;
+ float x4 = x0 - 1.0f + 4.0f*G4; // Offsets for last corner in (x,y,z,w) coords
+ float y4 = y0 - 1.0f + 4.0f*G4;
+ float z4 = z0 - 1.0f + 4.0f*G4;
+ float w4 = w0 - 1.0f + 4.0f*G4;
+
+ // Wrap the integer indices at 256, to avoid indexing perm[] out of bounds
+ int ii = i & 0xff;
+ int jj = j & 0xff;
+ int kk = k & 0xff;
+ int ll = l & 0xff;
+
+ // Calculate the contribution from the five corners
+ float 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);
+ }
+
+ float 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);
+ }
+
+ float 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);
+ }
+
+ float 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);
+ }
+
+ float 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!
+}
diff --git a/util.h b/util.h
@@ -35,5 +35,11 @@ struct model {
struct model *load_wavefront_obj(const char *fn);
+/* simplex noise */
+float snoise(float x);
+float snoise(float x, float y);
+float snoise(float x, float y, float z);
+float snoise(float x, float y, float z, float w);
+
#endif
