52 lines
1.2 KiB
GLSL
52 lines
1.2 KiB
GLSL
// based on https://www.shadertoy.com/view/4dS3Wd
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// uniforms
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uniform vec4 gain;
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uniform vec4 bias;
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uniform vec2 seed;
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uniform vec2 scale;
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uniform vec2 lacunarity;
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uniform vec4 decay;
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uniform int octaves;
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uniform bool premultipliedAlpha;
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// varyings
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in vec2 v_texCoord0;
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// outputs
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out vec4 o_output;
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float hash(vec2 p) { return fract(1e4 * sin(17.0 * p.x + p.y * 0.1) * (0.1 + abs(sin(p.y * 13.0 + p.x)))); }
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float noise(vec2 x) {
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vec2 i = floor(x);
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vec2 f = fract(x);
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float a = hash(i);
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float b = hash(i + vec2(1.0, 0.0));
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float c = hash(i + vec2(0.0, 1.0));
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float d = hash(i + vec2(1.0, 1.0));
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vec2 u = f * f * (3.0 - 2.0 * f);
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return mix(a, b, u.x) + (c - a) * u.y * (1.0 - u.x) + (d - b) * u.x * u.y;
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}
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void main() {
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vec4 result = vec4(0.0);
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vec4 _gain = gain;
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vec2 shift = vec2(100);
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mat2 rot = mat2(cos(0.5), sin(0.5), -sin(0.5), cos(0.50));
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vec2 x = ((v_texCoord0+seed) * scale);
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for (int o = 0; o < octaves; ++o) {
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result += noise(x) * _gain;
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x = rot * x * lacunarity + shift;
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_gain *= decay;
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}
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o_output = result + bias;
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if (premultipliedAlpha) {
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o_output.rgb *= o_output.a;
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}
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} |