#ifdef GL_ES | |
precision mediump float; | |
#endif | |
#extension GL_OES_standard_derivatives : enable | |
uniform float time; | |
uniform vec2 mouse; | |
uniform vec2 resolution; | |
struct Ray { | |
vec3 pos; | |
vec3 dir; | |
}; | |
// Some useful functions | |
vec3 mod289(vec3 x) { return x - floor(x * (1.0 / 289.0)) * 289.0; } | |
vec2 mod289(vec2 x) { return x - floor(x * (1.0 / 289.0)) * 289.0; } | |
vec3 permute(vec3 x) { return mod289(((x*34.0)+1.0)*x); } | |
// | |
// Description : GLSL 2D simplex noise function | |
// Author : Ian McEwan, Ashima Arts | |
// Maintainer : ijm | |
// Lastmod : 20110822 (ijm) | |
// License : | |
// Copyright (C) 2011 Ashima Arts. All rights reserved. | |
// Distributed under the MIT License. See LICENSE file. | |
// https://github.com/ashima/webgl-noise | |
// | |
float snoise(vec2 v) { | |
// Precompute values for skewed triangular grid | |
const vec4 C = vec4(0.211324865405187, | |
// (3.0-sqrt(3.0))/6.0 | |
0.366025403784439, | |
// 0.5*(sqrt(3.0)-1.0) | |
-0.577350269189626, | |
// -1.0 + 2.0 * C.x | |
0.024390243902439); | |
// 1.0 / 41.0 | |
// First corner (x0) | |
vec2 i = floor(v + dot(v, C.yy)); | |
vec2 x0 = v - i + dot(i, C.xx); | |
// Other two corners (x1, x2) | |
vec2 i1 = vec2(0.0); | |
i1 = (x0.x > x0.y)? vec2(1.0, 0.0):vec2(0.0, 1.0); | |
vec2 x1 = x0.xy + C.xx - i1; | |
vec2 x2 = x0.xy + C.zz; | |
// Do some permutations to avoid | |
// truncation effects in permutation | |
i = mod289(i); | |
vec3 p = permute( | |
permute( i.y + vec3(0.0, i1.y, 1.0)) | |
+ i.x + vec3(0.0, i1.x, 1.0 )); | |
vec3 m = max(0.5 - vec3( | |
dot(x0,x0), | |
dot(x1,x1), | |
dot(x2,x2) | |
), 0.0); | |
m = m*m ; | |
m = m*m ; | |
// Gradients: | |
// 41 pts uniformly over a line, mapped onto a diamond | |
// The ring size 17*17 = 289 is close to a multiple | |
// of 41 (41*7 = 287) | |
vec3 x = 2.0 * fract(p * C.www) - 1.0; | |
vec3 h = abs(x) - 0.5; | |
vec3 ox = floor(x + 0.5); | |
vec3 a0 = x - ox; | |
// Normalise gradients implicitly by scaling m | |
// Approximation of: m *= inversesqrt(a0*a0 + h*h); | |
m *= 1.79284291400159 - 0.85373472095314 * (a0*a0+h*h); | |
// Compute final noise value at P | |
vec3 g = vec3(0.0); | |
g.x = a0.x * x0.x + h.x * x0.y; | |
g.yz = a0.yz * vec2(x1.x,x2.x) + h.yz * vec2(x1.y,x2.y); | |
return 130.0 * dot(m, g); | |
} | |
float map(vec3 v) { | |
const float GROUND_BASE = 1.2; | |
return v.y - snoise(v.xz * .4) + GROUND_BASE; | |
} | |
vec3 map_normal(vec3 v) { | |
float delta = 0.01; | |
return normalize(vec3(map(v + vec3(delta, 0.0, 0.0)) - map(v), | |
map(v + vec3(0.0, delta, 0.0)) - map(v), | |
map(v + vec3(0.0, 0.0, delta)) - map(v))); | |
} | |
void main( void ) { | |
vec2 pos = (gl_FragCoord.xy * 2.0 - resolution) / max(resolution.x, resolution.y); | |
// カメラの位置。中心から後方にあるイメージ | |
vec3 camera_pos = vec3(time, 0.0, -4.0 + time); | |
// カメラの上方向の姿勢を定めるベクトル この場合水平 | |
vec3 camera_up = normalize(vec3(0.0, 1.0, 0.0)); | |
// カメラの向いている方向 | |
vec3 camera_dir = normalize(vec3(0.0, 0.0, 1.0)); | |
// camera_upとcamera_dirの外積から定まるカメラの横方向のベクトル | |
vec3 camera_side = normalize(cross(camera_up, camera_dir)); | |
// レイの位置、飛ぶ方向を定義する | |
Ray ray; | |
ray.pos = camera_pos; | |
ray.dir = normalize(pos.x * camera_side + pos.y * camera_up + camera_dir); | |
float t = 0.0, d; | |
// レイを飛ばす (計算回数は最大64回まで) | |
for (int i = 0; i < 128; i++) { | |
d = map(ray.pos); | |
// ヒットした | |
if (d < 0.001) { | |
break; | |
} | |
// 次のレイは最小距離d * ray.dirの分だけ進める(効率化) | |
t += d; | |
ray.pos = camera_pos + t * ray.dir; | |
} | |
vec3 L = normalize(vec3(0.0, 1.0, 0.0)); // 光源ベクトル | |
vec3 N = map_normal(ray.pos); // 法線ベクトル | |
vec3 LColor = vec3(1.0, 1.0, 1.0); // 光の色 | |
vec3 I = dot(N, L) * LColor; // 輝度 | |
if (d < 0.001) { | |
// ヒットしていれば白 | |
gl_FragColor = vec4(I, 1.0); | |
} else { | |
gl_FragColor = vec4(0); | |
} | |
} |
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