pretty crazy organic mandelbrot

Assets/Scenes/GFLPC_Mandelbrot/Mandelbrot.shader

@@ -7,13 +7,12 @@ 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
         _Symmetry("Symmetry", range(0, 1)) = 0
         _EscapeRadius("EscapeRadius", range(2, 200)) = 50
 
         _SpectrumTexture("SpectrumTexture", 2D) = "white" {}
+        _ThemeTexture("ThemeTexture", 2D) = "white" {}
         _SpectrumSize("SpectrumSize", float) = 16
 
     }
@@ -52,14 +51,13 @@ Shader "Explorer/Mandelbrot"
 
             float4 _Area;
             float _Angle;
-            float _Color;
-            float _Repeat;
             float _Speed;
             float _Symmetry;
             float _EscapeRadius;
             int _MaxIter;
             sampler2D _MainTex;
             sampler2D _SpectrumTexture;
+            sampler2D _ThemeTexture;
 
             float2 rot(float2 p, float2 pivot, float a) {
                 float s = sin(a);
@@ -78,18 +76,33 @@ Shader "Explorer/Mandelbrot"
                 uv = lerp(i.uv - 0.5, uv, _Symmetry);
                 float2 c = _Area.xy + uv * _Area.zw;
                 c = rot(c, _Area.xy, _Angle);
+
+                // cool modulation
+                float time = _Time.y;
+                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);
+                // float maxIterations = lerp(2.0, 500, sub);
+                // float speed = sub * -scale;
+
+                float maxIterations = _MaxIter;
+                // float r = _EscapeRadius;
+                float speed = _Speed;
+
                 float2 z;  // track pixel jumping across screen
                 float2 zPrev;
-                // float r = _EscapeRadius;
-                float r = lerp(2.0f, 50.0f, tex2D(_SpectrumTexture, 1.0f));
                 float r2 = r*r;
 
                 float iter;  // track current iteration
                 for (iter = 0; iter < _MaxIter; iter++) {
                     // update z based on previous z value and add original starting position
                     // zPrev = z;
-                    zPrev = rot(z, 0, _Time.y);
-                    // zPrev = rot(z, 0, clamp(tex2D(_SpectrumTexture, 0.1f) * 6.28, 1, 6.28));
+                    float rotation = sin(time);
+                    zPrev = rot(z, 0, rotation);
 
                     z = float2(z.x*z.x-z.y*z.y, 2*z.x*z.y) + c;
                     if (dot(z, zPrev) > r2) {
@@ -100,18 +113,20 @@ Shader "Explorer/Mandelbrot"
                 if (iter >= _MaxIter) {
                     return 0;
                 }
+
                 float dist  = length(z); // distance from origin
                 float fracIter  = (dist - r) / (r2 - r); // linear interpolation
                 fracIter = log2(log(dist) / log(r)); // double exponential interpolation
-                iter -= fracIter;
+                // iter -= fracIter;
                 float m = sqrt(iter / _MaxIter);
-                float4 col = sin(float4(.3, .45, .65, 1) * m * 20)*.5 + .5; // procedural colors
-                col = tex2D(_MainTex, float2(m * _Repeat + _Time.y*_Speed, _Color));
+                // float4 col = tex2D(_ThemeTexture, m + abs(sin(time)) * speed);
+                float4 col = tex2D(_ThemeTexture, m + time * speed);
                 col *= smoothstep(3, 0, fracIter);
 
+                // dark bands
                 float angle = atan2(z.x, z.y);
+                col *= 1 + sin(angle*2 + time*4)*.2;
 
-                col *= 1 + sin(angle*2 + _Time.y*4)*.2;
                 return col;
             }
             ENDCG