theme mandelbrot

Assets/Scenes/GFLPC_Mandelbrot/MandelBrotHybrid.shader

@@ -7,10 +7,15 @@ Shader "Explorer/Mandelbrot"
         _Area("Area", vector) = (0, 0, 4 ,4)
         _Angle("Angle", range(-3.1415, 3.1415)) = 0
         _MaxIter("Max Iterations", range(0, 555)) = 255
-        _Color("Color", range(0,1)) = 0.5
-        _Repeat("Repeat", float) =  1
         _Speed("Speed", range(0, 1)) = 0.1
-        _Colors("Colors", vector) = (3.0, 4.0, 5.0, 0.0)
+        _EscapeRadius("EscapeRadius", range(2, 2000)) = 255
+
+        _SpectrumTexture("SpectrumTexture", 2D) = "white" {}
+        _SpectrumSize("SpectrumSize", float) = 16
+
+        _ThemeTexture("ThemeTexture", 2D) = "white" {}
+        _ThemeSize("ThemeSize", float) = 16
+
     }
     SubShader
     {
@@ -46,54 +51,68 @@ Shader "Explorer/Mandelbrot"
             }
 
             float4 _Area;
-            float _Angle;
-            float _Color;
-            float3  _Colors;
-            float _Repeat;
-            float _Speed;
             int _MaxIter;
+            float _EscapeRadius;
+            float _Speed;
+
+            sampler2D _SpectrumTexture;
+            int _SpectrumSize;
+
+            sampler2D _ThemeTexture;
+            int _ThemeSize;
+
             sampler2D _MainTex;
 
-            float2 rot(float2 p, float2 pivot, float a) {
-                float s = sin(a);
-                float c = cos(a);
-                p -= pivot;
-                p = float2(p.x*c-p.y*s, p.x*s+p.y*c);
-                p += pivot;
-
-                return p;
-            }
-
             fixed4 frag (v2f i) : SV_Target {
+                // drawing stuff
                 float2 uv = i.uv - 0.5;
                 float2 offset = _Area.xy + uv * _Area.zw;
-                float2 z;  // track pixel jumping across screen
-                float2 zPrev;
-                float r = 20;  // escape radius
+
+                // cool modulation
+                float sub = tex2D(_SpectrumTexture, 0.0);
+                float bass = tex2D(_SpectrumTexture, 0.25);
+                float mids = tex2D(_SpectrumTexture, 0.50);
+                float highs = tex2D(_SpectrumTexture, 0.75);
+
+                float r = lerp(2.0, 200, bass);
+                float maxIterations = lerp(2.0, 500, sub);
+
+                // fractal bits
                 float r2 = r*r;
+                float2 c = _Area.xy + uv * _Area.zw;
+                float2 z = 0;
+                float2 zNext;
+                int iter;
+                for (iter = 0; iter < maxIterations; iter ++)
+                {
+                    // f(z) = z^2 + c
+                    zNext.x = z.x * z.x - z.y * z.y   + c.x;
+                    zNext.y = 2 * z.x * z.y           + c.y;
+                    z = zNext;
 
-                float vxsquare = 0;
-                float vysquare = 0;
+                    // unbounded
+                    if (length(zNext) > r)
+                        break;
+                }
 
-                float iteration = 0;
-                float lastIteration = _MaxIter;
+                // in the set
+                // make it white
+                if (iter >= maxIterations) {
+                    return 0;
+                    return 1;
+                }
 
-                do {
-                    vxsquare = uv.x * uv.x;
-                    vysquare = uv.y * uv.y;
+                float val = iter / float(maxIterations);
+                float4 col = tex2D(_ThemeTexture, float2(sub, 1.0));
 
-                    uv = float2(vxsquare - vysquare, uv.x * uv.y * 2) + offset;
+                return col * val;
 
-                    iteration++;
-
-                    if ((lastIteration == _MaxIter) && (vxsquare + vysquare) > 4.0) {
-                        lastIteration = iteration + 1;
-                    }
-                } while (iteration < lastIteration);
-
-                float val = (float(iteration) - (log(log(sqrt(vxsquare + vysquare))) / log(2.0))) / float(_MaxIter);
-                return float4(sin(val * _Colors.x), sin(val * _Colors.y), sin(val * _Colors.z), 1);
+                // return float4(val, val, val, 1.0);
+                // return tex2D(_ThemeTexture, highs);
+                // float col = tex2D(_ThemeTexture, float2(highs * val, 1.0));
+                // return col;
 
+                // from spinny curvy brot
                 // float dist  = length(z); // distance from origin
                 // float fracIter  = (dist - r) / (r2 - r); // linear interpolation
                 // fracIter = log2(log(dist) / log(r) ); // double exponential interpolation