124 lines
3.2 KiB
GLSL
124 lines
3.2 KiB
GLSL
shader_type canvas_item;
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uniform vec2 u_offset;
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uniform float u_scale = 0.02;
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uniform float u_base_height = 0.0;
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uniform float u_height_range = 100.0;
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uniform int u_seed;
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uniform int u_octaves = 5;
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uniform float u_roughness = 0.5;
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uniform float u_curve = 1.0;
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uniform vec2 u_uv_offset;
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uniform vec2 u_uv_scale = vec2(1.0, 1.0);
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////////////////////////////////////////////////////////////////////////////////
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// Perlin noise source:
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// https://github.com/curly-brace/Godot-3.0-Noise-Shaders
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//
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// GLSL textureless classic 2D noise \"cnoise\",
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// with an RSL-style periodic variant \"pnoise\".
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// Author: Stefan Gustavson (stefan.gustavson@liu.se)
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// Version: 2011-08-22
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//
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// Many thanks to Ian McEwan of Ashima Arts for the
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// ideas for permutation and gradient selection.
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//
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// Copyright (c) 2011 Stefan Gustavson. All rights reserved.
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// Distributed under the MIT license. See LICENSE file.
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// https://github.com/stegu/webgl-noise
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//
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vec4 mod289(vec4 x) {
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return x - floor(x * (1.0 / 289.0)) * 289.0;
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}
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vec4 permute(vec4 x) {
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return mod289(((x * 34.0) + 1.0) * x);
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}
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vec4 taylorInvSqrt(vec4 r) {
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return 1.79284291400159 - 0.85373472095314 * r;
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}
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vec2 fade(vec2 t) {
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return t * t * t * (t * (t * 6.0 - 15.0) + 10.0);
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}
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// Classic Perlin noise
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float cnoise(vec2 P) {
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vec4 Pi = floor(vec4(P, P)) + vec4(0.0, 0.0, 1.0, 1.0);
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vec4 Pf = fract(vec4(P, P)) - vec4(0.0, 0.0, 1.0, 1.0);
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Pi = mod289(Pi); // To avoid truncation effects in permutation
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vec4 ix = Pi.xzxz;
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vec4 iy = Pi.yyww;
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vec4 fx = Pf.xzxz;
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vec4 fy = Pf.yyww;
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vec4 i = permute(permute(ix) + iy);
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vec4 gx = fract(i * (1.0 / 41.0)) * 2.0 - 1.0 ;
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vec4 gy = abs(gx) - 0.5 ;
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vec4 tx = floor(gx + 0.5);
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gx = gx - tx;
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vec2 g00 = vec2(gx.x,gy.x);
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vec2 g10 = vec2(gx.y,gy.y);
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vec2 g01 = vec2(gx.z,gy.z);
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vec2 g11 = vec2(gx.w,gy.w);
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vec4 norm = taylorInvSqrt(vec4(dot(g00, g00), dot(g01, g01), dot(g10, g10), dot(g11, g11)));
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g00 *= norm.x;
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g01 *= norm.y;
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g10 *= norm.z;
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g11 *= norm.w;
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float n00 = dot(g00, vec2(fx.x, fy.x));
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float n10 = dot(g10, vec2(fx.y, fy.y));
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float n01 = dot(g01, vec2(fx.z, fy.z));
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float n11 = dot(g11, vec2(fx.w, fy.w));
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vec2 fade_xy = fade(Pf.xy);
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vec2 n_x = mix(vec2(n00, n01), vec2(n10, n11), fade_xy.x);
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float n_xy = mix(n_x.x, n_x.y, fade_xy.y);
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return 2.3 * n_xy;
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}
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////////////////////////////////////////////////////////////////////////////////
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float get_fractal_noise(vec2 uv) {
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float scale = 1.0;
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float sum = 0.0;
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float amp = 0.0;
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int octaves = u_octaves;
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float p = 1.0;
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uv.x += float(u_seed) * 61.0;
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for (int i = 0; i < octaves; ++i) {
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sum += p * cnoise(uv * scale);
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amp += p;
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scale *= 2.0;
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p *= u_roughness;
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}
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float gs = sum / amp;
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return gs;
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}
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float get_height(vec2 uv) {
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float h = 0.5 + 0.5 * get_fractal_noise(uv);
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h = pow(h, u_curve);
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h = u_base_height + h * u_height_range;
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return h;
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}
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void fragment() {
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vec2 uv = SCREEN_UV;
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// Handle screen padding: transform UV back into generation space
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uv = (uv + u_uv_offset) * u_uv_scale;
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// Offset and scale for the noise itself
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uv = (uv + u_offset) * u_scale;
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float h = get_height(uv);
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COLOR = vec4(h, h, h, 1.0);
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}
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