added helpful docs to the vector cross and dot functions.

added createPlane2ColorShader to improve edge detection.

Author: rhulha

lib/chronosgl.dart

@@ -72,7 +72,6 @@ class ChronosGL
     // fix a bug in current chrome v.27
     _canvas.onDragStart.listen((HTML.MouseEvent event){ event.preventDefault(); });
 
-    // TODO: add resize handler
     _canvas.width = _canvas.clientWidth; 
     _canvas.height = _canvas.clientHeight;
     _aspect = _canvas.clientWidth / _canvas.clientHeight;

lib/src/shader_lib.dart

@@ -128,21 +128,85 @@ class ShaderLib {
         uniform mat4 uMVMatrix;
         uniform mat4 uPMatrix;
         
-        varying vec3 vNormal;
+        varying vec3 vColor;
 
         void main(void) {
           gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
-          vNormal = aNormal;
+          vColor=normalize( aNormal / 2.0 + vec3(0.5) );
         }
         """;
 
     shaderObject.fragmentShader = """
         precision mediump float;
         
-        varying vec3 vNormal;
+        varying vec3 vColor;
+
+        void main(void) {
+          gl_FragColor = vec4( vColor, 1.0 );
+        }
+        """;
+    
+    shaderObject.vertexPositionAttribute = "aVertexPosition"; 
+    shaderObject.normalAttribute = "aNormal";
+    shaderObject.modelViewMatrixUniform = "uMVMatrix";
+    shaderObject.perpectiveMatrixUniform = "uPMatrix";
+    
+    return shaderObject;
+  }
+
+  ShaderObject createPlane2ColorShader() {
+    ShaderObject shaderObject = new ShaderObject();
+    
+    shaderObject.vertexShader = """
+        precision mediump float;
+
+        attribute vec3 aVertexPosition;
+        attribute vec3 aNormal;
+        
+        uniform mat4 uMVMatrix;
+        uniform mat4 uPMatrix;
+        
+        varying vec3 vColor;
 
+        vec3 HSV2RGB( vec3 hsv )
+        {
+            hsv.x = mod( 100.0 + hsv.x, 1.0 );                                       // Ensure [0,1[
+    
+            float   HueSlice = 6.0 * hsv.x;                                            // In [0,6[
+            float   HueSliceInteger = floor( HueSlice );
+            float   HueSliceInterpolant = HueSlice - HueSliceInteger;                   // In [0,1[ for each hue slice
+    
+            vec3  TempRGB = vec3(   hsv.z * (1.0 - hsv.y),
+                                        hsv.z * (1.0 - hsv.y * HueSliceInterpolant),
+                                        hsv.z * (1.0 - hsv.y * (1.0 - HueSliceInterpolant)) );
+    
+            float   IsOddSlice = mod( HueSliceInteger, 2.0 );                          // 0 if even (slices 0, 2, 4), 1 if odd (slices 1, 3, 5)
+            float   ThreeSliceSelector = 0.5 * (HueSliceInteger - IsOddSlice);          // (0, 1, 2) corresponding to slices (0, 2, 4) and (1, 3, 5)
+    
+            vec3  ScrollingRGBForEvenSlices = vec3( hsv.z, TempRGB.zx );           // (V, Temp Blue, Temp Red) for even slices (0, 2, 4)
+            vec3  ScrollingRGBForOddSlices = vec3( TempRGB.y, hsv.z, TempRGB.x );  // (Temp Green, V, Temp Red) for odd slices (1, 3, 5)
+            vec3  ScrollingRGB = mix( ScrollingRGBForEvenSlices, ScrollingRGBForOddSlices, IsOddSlice );
+    
+            float   IsNotFirstSlice = clamp( ThreeSliceSelector, 0.0,1.0 );                   // 1 if NOT the first slice (true for slices 1 and 2)
+            float   IsNotSecondSlice = clamp( ThreeSliceSelector-1.0, 0.0,1. );              // 1 if NOT the first or second slice (true only for slice 2)
+    
+            return  mix( ScrollingRGB.xyz, mix( ScrollingRGB.zxy, ScrollingRGB.yzx, IsNotSecondSlice ), IsNotFirstSlice );    // Make the RGB rotate right depending on final slice index
+        }
+
+        void main(void) {
+          gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
+          float d=dot( aVertexPosition, aNormal);
+          vec3 hsv = vec3(d,1,1);
+          vColor=HSV2RGB(hsv);
+        }
+        """;
+    
+    shaderObject.fragmentShader = """
+        precision mediump float;
+
+        varying vec3 vColor;
         void main(void) {
-          gl_FragColor = vec4( normalize( vNormal / 2.0 + vec3(0.5) ), 1.0 );
+          gl_FragColor = vec4( vColor, 1.0 );
         }
         """;
 

lib/src/vector.dart

@@ -120,6 +120,9 @@ class Vector {
     return this;
   }
 
+  // The cross product results in a vector perpendicular to the two input vectors
+  // The result's magnitude is equal to the magnitudes of the two inputs multiplied together and then multiplied by the sine of the angle between the inputs.
+  // Or in other words the result's magnitude is equal to the area of the parallelogram that the two input vectors span.
   Vector cross( Vector vec2) {
     return cross2( this, vec2);
   }
@@ -134,6 +137,8 @@ class Vector {
     return this;
   }
 
+  // The dot product is a float value equal to the magnitudes of the two vectors multiplied together and then multiplied by the cosine of the angle between them.
+  // For normalized vectors Dot returns 1 if they point in exactly the same direction, -1 if they point in completely opposite directions and zero if the vectors are perpendicular.
   double dot( Vector vec2) {
     return array[0] * vec2[0] + array[1] * vec2[1] + array[2] * vec2[2];
   }