From 7bc62d185024c485e386de941b3b686be6313ed4 Mon Sep 17 00:00:00 2001
From: cale bradbury <cale.bradbury@gmail.com>
Date: Fri, 18 Nov 2016 00:51:44 -0400
Subject: [PATCH] Added chromatic aberration filter

---
 scripts/modules/filter.js | 73 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 72 insertions(+), 1 deletion(-)

diff --git a/scripts/modules/filter.js b/scripts/modules/filter.js
index a462655..c52ef3e 100644
--- a/scripts/modules/filter.js
+++ b/scripts/modules/filter.js
@@ -16,6 +16,9 @@ function Filter(element)
       case "saturation":
         this.filter_saturation(this.pixels(),p);
         break;
+      case "chromatic":
+        this.filter_chromatic(this.pixels(),p);
+        break;
     }
   }
   
@@ -41,10 +44,78 @@ function Filter(element)
   	ronin.canvas.context().putImageData(pixels, 0, 0, 0, 0, pixels.width, pixels.height);
   }
   
+  this.filter_chromatic = function(pixels = this.pixels(),p = null)
+  {
+  	var s;
+		if(p.length == 0)
+			s = {r:2,g:2,b:2};
+		else if(p.length < 3)
+			s = {r:parseFloat(p[0]), g:parseFloat(p[0])*.5, b:0};
+		else
+			s = {r:parseFloat(p[0]), g:parseFloat(p[1]), b:parseFloat(p[2])};
+		var hw = pixels.width*.5;
+		var hh = pixels.height*.5;
+		var maxLength = Math.sqrt(hw*hw+hh*hh);
+		var output = new ImageData(pixels.width, pixels.height);
+    for (var i=0; i<pixels.width; i++) {
+				for(var j=0; j<pixels.height; j++){
+					var x = i-hw;
+					var y = j-hh;
+					var a = Math.atan2(y,x);
+					var d = Math.sqrt(x*x+y*y);
+					var f = (d-s.r*d/maxLength);
+					x = Math.cos(a)*f+hw;
+					y = Math.sin(a)*f+hh;
+					var r = this.get_color_bilinear(pixels, x, y);
+					f = (d-s.g*d/maxLength);
+					x = Math.cos(a)*f+hw;
+					y = Math.sin(a)*f+hh;
+					var g = this.get_color_bilinear(pixels, x, y);
+					f = (d-s.b*d/maxLength);
+					x = Math.cos(a)*f+hw;
+					y = Math.sin(a)*f+hh;
+					var b = this.get_color_bilinear(pixels, x, y);
+					var c = {r:r.r, g:g.g, b:b.b,a:Math.max(r.a, Math.max(g.a,b.a))};
+					this.set_color(output, c, i,j);
+				}
+    }
+  	ronin.canvas.clear();
+  	ronin.canvas.context().putImageData(output, 0, 0, 0, 0, pixels.width, pixels.height);
+  }
+	
+	this.set_color = function(pixels, color, x, y){
+		x = Math.max(0,Math.min(x,pixels.width-1));
+		y = Math.max(0,Math.min(y,pixels.height-1));
+		var index = (x+y*pixels.width)*4;
+		pixels.data[index] = color.r;
+		pixels.data[index+1] = color.g;
+		pixels.data[index+2] = color.b;
+		pixels.data[index+3] = color.a;
+	}
+	
+	this.get_color = function(pixels,x,y){
+		x = Math.max(0,Math.min(x,pixels.width-1));
+		y = Math.max(0,Math.min(y,pixels.height-1));
+		var index = (x+y*pixels.width)*4;
+		return {r:pixels.data[index], g:pixels.data[index+1], b:pixels.data[index+2], a:pixels.data[index+3]};
+	}
+	
+	this.get_color_bilinear = function(pixels, x, y){
+		var c1 = this.get_color(pixels, Math.floor(x),Math.floor(y));
+		var c2 = this.get_color(pixels, Math.ceil(x),Math.floor(y));
+		var c3 = this.get_color(pixels, Math.floor(x),Math.ceil(y));
+		var c4 = this.get_color(pixels, Math.ceil(x),Math.ceil(y));
+		return this.lerp_color(this.lerp_color(c1,c2, x%1),this.lerp_color(c3,c4, x%1), y%1);
+	}
+	
+	this.lerp_color = function(c1, c2, t){
+		return {r:c1.r+t*(c2.r-c1.r), g:c1.g+t*(c2.g-c1.g), b:c1.b+t*(c2.b-c1.b), a:c1.a+t*(c2.a-c1.a)};
+	}
+  
   //
   
   this.pixels = function()
   {
     return ronin.canvas.context().getImageData(0,0,ronin.canvas.element.width,ronin.canvas.element.height);
   }
-}
\ No newline at end of file
+}