noise3D.h

#pragma once

#include <noise/platform.h>
#include <noise/noise_common.h>

#include <noise/platform_glm_define.h>

NOISE_BEGIN_NAMESPACE

NOISE_INLINE float snoise(vec3 v)
{
	const vec2  C = vec2(1.0 / 6.0, 1.0 / 3.0);
	const vec4  D = vec4(0.0, 0.5, 1.0, 2.0);

	// First corner
	vec3 i = floor(v + dot(v, C.yyy));
	vec3 x0 = v - i + dot(i, C.xxx);

	// Other corners
	vec3 g = step(x0.yzx, x0.xyz);
	vec3 l = vec3(1.0) - g;
	vec3 i1 = min(g.xyz, l.zxy);
	vec3 i2 = max(g.xyz, l.zxy);

	//   x0 = x0 - 0.0 + 0.0 * C.xxx;
	//   x1 = x0 - i1  + 1.0 * C.xxx;
	//   x2 = x0 - i2  + 2.0 * C.xxx;
	//   x3 = x0 - 1.0 + 3.0 * C.xxx;
	vec3 x1 = x0 - i1 + C.xxx;
	vec3 x2 = x0 - i2 + C.yyy; // 2.0*C.x = 1/3 = C.y
	vec3 x3 = x0 - D.yyy;      // -1.0+3.0*C.x = -0.5 = -D.y

  // Permutations
	i = mod289(i);
	vec4 p = permute(permute(permute(
		i.z + vec4(0.0, i1.z, i2.z, 1.0))
		+ i.y + vec4(0.0, i1.y, i2.y, 1.0))
		+ i.x + vec4(0.0, i1.x, i2.x, 1.0));

	// Gradients: 7x7 points over a square, mapped onto an octahedron.
	// The ring size 17*17 = 289 is close to a multiple of 49 (49*6 = 294)
	float n_ = 0.142857142857f; // 1.0/7.0
	vec3  ns = n_ * D.wyz - D.xzx;

	vec4 j = p - 49.0 * floor(p * ns.z * ns.z);  //  mod(p,7*7)

	vec4 x_ = floor(j * ns.z);
	vec4 y_ = floor(j - 7.0 * x_);    // mod(j,N)

	vec4 x = x_ *ns.x + ns.yyyy;
	vec4 y = y_ *ns.x + ns.yyyy;
	vec4 h = vec4(1.0) - abs(x) - abs(y);

	vec4 b0 = vec4(x.xy, y.xy);
	vec4 b1 = vec4(x.zw, y.zw);

	//vec4 s0 = vec4(lessThan(b0,0.0))*2.0 - 1.0;
	//vec4 s1 = vec4(lessThan(b1,0.0))*2.0 - 1.0;
	vec4 s0 = floor(b0)*2.0 + vec4(1.0);
	vec4 s1 = floor(b1)*2.0 + vec4(1.0);
	vec4 sh = -step(h, vec4(0.0));

	vec4 a0 = b0.xzyw + s0.xzyw*sh.xxyy;
	vec4 a1 = b1.xzyw + s1.xzyw*sh.zzww;

	vec3 p0 = vec3(a0.xy, h.x);
	vec3 p1 = vec3(a0.zw, h.y);
	vec3 p2 = vec3(a1.xy, h.z);
	vec3 p3 = vec3(a1.zw, h.w);

	//Normalise gradients
	vec4 norm = taylorInvSqrt(vec4(dot(p0, p0), dot(p1, p1), dot(p2, p2), dot(p3, p3)));
	p0 *= norm.x;
	p1 *= norm.y;
	p2 *= norm.z;
	p3 *= norm.w;

	// Mix final noise value
	vec4 m = max(vec4(0.6f) - vec4(dot(x0, x0), dot(x1, x1), dot(x2, x2), dot(x3, x3)), vec4(0.0f));

	m = m * m;
	return 42.0f * dot(m*m, vec4(dot(p0, x0), dot(p1, x1),
		dot(p2, x2), dot(p3, x3)));
}

NOISE_END_NAMESPACE

#include <noise/platform_glm_undef.h>