mad fractal action

Assets/Scenes/GFLPC_Mandelbrot/Mandelbrot.shader

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+Shader "Explorer/Mandelbrot"
+{
+    Properties
+    {
+        _MainTex ("Texture", 2D) = "white" {}
+        // first two numbers are center of area, second two - size of area
+        _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(0, 50)) = 20
+
+        _SpectrumTexture("SpectrumTexture", 2D) = "white" {}
+        _SpectrumSize("SpectrumSize", float) = 16
+
+    }
+    SubShader
+    {
+        // No culling or depth
+        Cull Off ZWrite Off ZTest Always
+
+        Pass
+        {
+            CGPROGRAM
+            #pragma vertex vert
+            #pragma fragment frag
+
+            #include "UnityCG.cginc"
+
+            struct appdata
+            {
+                float4 vertex : POSITION;
+                float2 uv : TEXCOORD0;
+            };
+
+            struct v2f
+            {
+                float2 uv : TEXCOORD0;
+                float4 vertex : SV_POSITION;
+            };
+
+            v2f vert (appdata v)
+            {
+                v2f o;
+                o.vertex = UnityObjectToClipPos(v.vertex);
+                o.uv = v.uv;
+                return o;
+            }
+
+            float4 _Area;
+            float _Angle;
+            float _Color;
+            float _Repeat;
+            float _Speed;
+            float _Symmetry;
+            float _EscapeRadius;
+            int _MaxIter;
+            sampler2D _MainTex;
+            sampler2D _SpectrumTexture;
+
+            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
+            {
+                float2 uv = i.uv - 0.5;
+                uv = abs(uv);
+                uv = lerp(i.uv - 0.5, uv, _Symmetry);
+                float2 c = _Area.xy + uv * _Area.zw;
+                c = rot(c, _Area.xy, _Angle);
+                float2 z;  // track pixel jumping across screen
+                float2 zPrev;
+                float r = lerp(2.0f, 20.0f, tex2D(_SpectrumTexture, 0.1f));
+                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);
+                    z = float2(z.x*z.x-z.y*z.y, 2*z.x*z.y) + c;
+                    if (dot(z, zPrev) > r2) {
+                    //if (length(z) > r) {
+                        break;
+                    }
+                }
+
+                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;
+                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));
+                col *= smoothstep(3, 0, fracIter);
+
+                float angle = atan2(z.x, z.y);
+
+                col *= 1 + sin(angle*2 + _Time.y*4)*.2;
+                return col;
+            }
+            ENDCG
+        }
+    }
+}