[orx-noise] Bring back GLSL NoiseFilters.kt (#277)

orx-noise/src/shaders/glsl/noise/value.frag

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