Distortion shader with final params

unity/Assets/Scripts/ImageSynthesis/Shaders/BarrelDistortion.shader

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+// latest
+
+Shader "Hidden/BarrelDistortion" {
+     Properties
+     {
+         [MainTexture] _MainTex ("Base (RGB)", 2D) = "white" {}
+
+         _LensDistortionStrength ("Lens Distortion Strength", Range (-20.0, 20.0))  = 1.0
+        //  _LensDistortionTightness ("Lens Distortion Power", Range (-20.0, 20.0))  = 7.0
+         _ZoomPercent ("Zoom Percent", Range (0.0, 5.0))  = 1.0
+
+
+          _k1 ("K1 polynomial dist coeff", Range (-8.0, 8.0))  = -0.126
+          _k2 ("K2 polynomial dist coeff", Range (-8.0, 8.0))  = 0.004
+          _k3 ("K3 polynomial dist coeff", Range (-18.0, 18.0))  = 0.0
+          _k4 ("K4 polynomial dist coeff", Range (-18.0, 18.0))  = 0.0
+
+          _DistortionIntensityX ("Distort Strength X", Range (0.0, 6.0)) = 1.0
+         _DistortionIntensityY ("Distort Strength Y", Range (0.0, 6.0)) = 1.0
+
+
+         _OutOfBoundColour ("Outline Color", Color) = (0.0, 0.0, 0.0, 1.0)
+     }
+     SubShader
+     {
+         Pass
+         {
+             CGPROGRAM
+
+              #pragma vertex vert
+             #pragma fragment frag
+             #include "UnityCG.cginc"
+
+              uniform sampler2D _MainTex;
+             uniform sampler2D _CameraDepthTexture;
+             uniform half4 _MainTex_TexelSize;
+
+             uniform float _LensDistortionStrength;
+             uniform float4 _OutOfBoundColour;
+            //  uniform float _LensDistortionTightness;
+
+             uniform float _ZoomPercent;
+
+            uniform float _DistortionIntensityX;
+            uniform float _DistortionIntensityY;
+
+             uniform float _k1;
+             uniform float _k2;
+             uniform float _k3;
+             uniform float _k4;
+
+
+            //  uniform float4 _ScreenParams;
+            //  uniform float4 _ProjectionParams;
+
+              struct input
+             {
+                 float4 pos : POSITION;
+                 half2 uv : TEXCOORD0;
+             };
+
+              struct output
+             {
+                 float4 pos : SV_POSITION;
+                 half2 uv : TEXCOORD0;
+             };
+
+
+              output vert(input i)
+             {
+                 output o;
+                 o.pos = UnityObjectToClipPos(i.pos);
+                //  o.uv = i.uv;
+                 o.uv = MultiplyUV(UNITY_MATRIX_TEXTURE0, i.uv);
+                //  o.uv.y = 1 - o.uv.y;
+                //  // why do we need this? cause sometimes the image I get is flipped. see: http://docs.unity3d.com/Manual/SL-PlatformDifferences.html
+                //  #if UNITY_UV_STARTS_AT_TOP
+                //  if (_MainTex_TexelSize.y < 0)
+                //          o.uv.y = 1 - o.uv.y;
+                //  #endif
+                // if (_ProjectionParams.x >= 0)
+                //     o.uv.y = 1 - o.uv.y;
+
+                  return o;
+             }
+
+              fixed4 frag(output o) : COLOR
+             {
+                float effect = _LensDistortionStrength;
+                float2 distortionStrengthXY = float2(_DistortionIntensityX, _DistortionIntensityY);
+                float zoom_offset = (1.0 - _ZoomPercent) / 2.0;
+
+                float2 centered_uv = o.uv - float2(0.5, 0.5);
+                centered_uv = o.uv*2.0 -  float2(1.0, 1.0);
+                //  centered_uv = o.uv -  float2(0.5, 0.5);
+
+                zoom_offset = (1.0 - _ZoomPercent);
+                centered_uv = (o.uv*2.0 * _ZoomPercent - float2(1.0, 1.0)) + float2(zoom_offset, zoom_offset);  
+
+
+
+                float uv_dot = dot(centered_uv, centered_uv);
+                float r = sqrt(uv_dot);
+                // // For Atan based distortion
+                float z = sqrt(1.0 - uv_dot * effect);
+                // float z = sqrt(1.0 - r * r);
+                float atan_distort = atan2(r, z) / UNITY_PI;
+
+                float atan_distortX = atan2(r, sqrt(1.0 - uv_dot * _DistortionIntensityX)) / UNITY_PI;
+                float atan_distortY = atan2(r, sqrt(1.0 - uv_dot * _DistortionIntensityY)) / UNITY_PI;
+                float2 distort_uv = (centered_uv / r) * atan_distort;//+ float2(0.5, 0.5);
+
+                distort_uv = (centered_uv / r) * float2(atan_distortX, atan_distortY);
+
+                //return t;
+
+                const float distortionMagnitude=abs(centered_uv.x*centered_uv.y);
+
+                float smoothDistortionMagnitude = 1.0 + _k1 * pow(r, 2.0) + _k2 * pow(r, 4.0) + _k3 * pow(r,6.0) + _k4 * pow(r,8.0);
+
+                float zoom_percent = 0.2;
+                float translate = (1.0 - zoom_percent) / 2.0;
+                float2 centered_uv_norm = normalize(centered_uv);
+
+
+
+                // Works with zoom for poly distortion
+                float2 uvDistorted = centered_uv * smoothDistortionMagnitude * distortionStrengthXY / 2.0 + float2(0.5, 0.5) ;
+
+                // working for atan distortion
+                // float2 uvDistorted = ( centered_uv / r ) * atan_distort + float2(0.5, 0.5);
+
+                // float2 uvDistorted = distort_uv + float2(0.5, 0.5);
+
+                // for xydistortion
+                // float2 uvDistorted = distort_uv*2.0 + float2(0.5, 0.5);
+
+            fixed4 col = tex2D(_MainTex, uvDistorted);
+            // Handle out of bound uv
+            if (uvDistorted.x < 0 || uvDistorted.x > 1 || uvDistorted.y < 0 || uvDistorted.y > 1) {
+                return _OutOfBoundColour;//uv out of bound so display out of bound color
+            } else {
+                return col;
+            }
+
+            // FOR atan radius cutoff
+            // float radius = 1.0;
+            //     if (uvDistorted.x > radius) {
+            //         return _OutOfBoundColour;
+            //     }
+            //     else {
+            //         return lerp(col1, col2, _BlendAmount);
+            //     }
+
+
+             }
+
+              ENDCG
+         }
+     } 
+ } 
+