1 files changed, 38 insertions, 1 deletions
diff --git a/public/assets/javascripts/rectangles/models/vec2.js b/public/assets/javascripts/rectangles/models/vec2.js
index 9c6fd99..4480473 100644
--- a/public/assets/javascripts/rectangles/models/vec2.js
+++ b/public/assets/javascripts/rectangles/models/vec2.js
@@ -80,7 +80,7 @@
 		return clamp(n, this.a+r, this.b-r)
 	}
 	vec2.prototype.intersects = function(v){
-		if (this.a == v.a) { // || this.b == v.b || this.a == v.b || this.b == v.a) {
+		if (this.a == v.a || this.b == v.b || this.a == v.b || this.b == v.a) {
 			return true
 		}
 		else if (this.a < v.a) {
@@ -106,6 +106,43 @@
 			return new vec2( max(this.a,v.a), min(this.b, v.b) )
 		}
 	}
+
+	// given two vectors, test how they overlap
+	// return the set of overlapping segments in the initial vector, labelled with sides
+	vec2.prototype.split = function(v, left, right){
+		var intervals = []
+
+		if (this.eq(v)) {
+			intervals.push([ new vec2( this.a, this.b ), left | right ])
+		}
+		
+		// a---A===b---B  (rightways overlap)
+		else if (this.contains(v.a) && v.contains(this.b)) {
+			intervals.push([ new vec2( this.a,    v.a ), left  ])
+			intervals.push([ new vec2(    v.a, this.b ), 0 ])
+		}
+
+    // A---a===B---b  (leftways overlap)
+		else if (v.contains(this.a) && this.contains(v.b)) {
+			intervals.push([ new vec2( this.a,    v.b ), 0  ])
+			intervals.push([ new vec2(    v.b, this.b ), right ])
+		}
+	
+		// a---A===B---b  (contains v)
+		else if (this.contains(v.a) && this.contains(v.b)) {
+			intervals.push([ new vec2( this.a,    v.a ), left  ])
+			intervals.push([ new vec2(    v.a, 	  v.b ), 0     ])
+			intervals.push([ new vec2(    v.b, this.b ), right ])
+		}
+		
+		// A---a===b---B  (contained in v)
+		else { // if (v.contains(this.a) && v.contains(v.b)) {
+			intervals.push([ new vec2( this.a, this.b ), 0 ])
+		}
+		
+		return intervals
+	}
+
 	vec2.prototype.toString = function(){
 		return "[" + ~~this.a + " " + ~~this.b + "]"
 	}