added vec2.reflect

examples/canvas/rayreflect.html

@@ -170,12 +170,6 @@
         ctx.stroke();
       };
 
-      function reflect(out, vector, normal){
-        var dot = vector[0]*normal[0] + vector[1]*normal[1];
-        out[0] = vector[0] - 2 * normal[0] * dot;
-        out[1] = vector[1] - 2 * normal[1] * dot;
-      };
-
       function drawRays(){
 
         for (var i = 0; i < 10; i++) {
@@ -200,7 +194,7 @@
             p2.vec2.copy(start, result.hitPointWorld);
 
             // reflect the direction
-            reflect(direction, direction, result.hitNormalWorld);
+            p2.vec2.reflect(direction, direction, result.hitNormalWorld);
 
             // move out a bit
             start[0] += direction[0] * 0.001;

src/math/vec2.js

@@ -482,10 +482,33 @@ vec2.str = function (a) {
     return 'vec2(' + a[0] + ', ' + a[1] + ')';
 };
 
+/**
+ * Linearly interpolate/mix two vectors.
+ * @static
+ * @method lerp
+ * @param {Array} out
+ * @param {Array} a First vector
+ * @param {Array} b Second vector
+ * @param {number} t Lerp factor
+ */
 vec2.lerp = function (out, a, b, t) {
     var ax = a[0],
         ay = a[1];
     out[0] = ax + t * (b[0] - ax);
     out[1] = ay + t * (b[1] - ay);
     return out;
 };
+
+/**
+ * Reflect a vector along a normal.
+ * @static
+ * @method reflect
+ * @param {Array} out
+ * @param {Array} vector
+ * @param {Array} normal
+ */
+vec2.reflect = function(out, vector, normal){
+    var dot = vector[0] * normal[0] + vector[1] * normal[1];
+    out[0] = vector[0] - 2 * normal[0] * dot;
+    out[1] = vector[1] - 2 * normal[1] * dot;
+};