UV Support on SubdivisionModifier

Simple, straight forward UV support for the subdivision modifier. If
uv's are present, it will work on them, if they're not, it shouldn't do
much of anything.

examples/js/modifiers/SubdivisionModifier.js

@@ -10,9 +10,9 @@
  *		http://www.cs.rutgers.edu/~decarlo/readings/subdiv-sg00c.pdf
  *
  *	Known Issues:
- *		- currently doesn't handle UVs
  *		- currently doesn't handle "Sharp Edges"
- *
+ * **UV Support By Matthew Adams / http://www.centerionware.com
+ * * DDS Images need to be upside down or UV's will be upside down. 
  */
 
 THREE.SubdivisionModifier = function ( subdivisions ) {
@@ -126,7 +126,12 @@ THREE.SubdivisionModifier.prototype.modify = function ( geometry ) {
 		newFaces.push( new THREE.Face3( a, b, c ) );
 
 	}
-
+	function midpoint(a, b) {
+	    return (Math.abs(b - a) / 2) + Math.min(a, b);
+	}
+	function newUv(newUvs, a, b, c) {
+	    newUvs.push([new THREE.Vector2(a.x, a.y), new THREE.Vector2(b.x, b.y), new THREE.Vector2(c.x, c.y)]);
+	}
 
 	/////////////////////////////
 
@@ -135,8 +140,8 @@ THREE.SubdivisionModifier.prototype.modify = function ( geometry ) {
 
 		var tmp = new THREE.Vector3();
 
-		var oldVertices, oldFaces;
-		var newVertices, newFaces; // newUVs = [];
+		var oldVertices, oldFaces, oldUvs;
+		var newVertices, newFaces, newUVs = [];
 
 		var n, l, i, il, j, k;
 		var metaVertices, sourceEdges;
@@ -146,7 +151,9 @@ THREE.SubdivisionModifier.prototype.modify = function ( geometry ) {
 
 		oldVertices = geometry.vertices; // { x, y, z}
 		oldFaces = geometry.faces; // { a: oldVertex1, b: oldVertex2, c: oldVertex3 }
-
+		oldUvs = geometry.faceVertexUvs[0];
+		var doUvs = false;
+		if (typeof (oldUvs) != 'undefined' && oldUvs.length != 0) doUvs = true;
 		/******************************************************
 		 *
 		 * Step 0: Preprocess Geometry to Generate edges Lookup
@@ -319,6 +326,10 @@ THREE.SubdivisionModifier.prototype.modify = function ( geometry ) {
 		var sl = newSourceVertices.length, edge1, edge2, edge3;
 		newFaces = [];
 
+		var x3 = new THREE.Vector2(0, 0);
+		var x4 = new THREE.Vector2(0, 0);
+		var x5 = new THREE.Vector2(0, 0);
+
 		for ( i = 0, il = oldFaces.length; i < il; i ++ ) {
 
 			face = oldFaces[ i ];
@@ -335,13 +346,66 @@ THREE.SubdivisionModifier.prototype.modify = function ( geometry ) {
 			newFace( newFaces, face.a, edge1, edge3 );
 			newFace( newFaces, face.b, edge2, edge1 );
 			newFace( newFaces, face.c, edge3, edge2 );
-
+		    // create 4 new uv's
+
+		    /*
+        
+
+0___________________C___________________2
+ \                 /\                  /
+  \              /   \      F4        /
+   \     F2    /       \             /
+    \        /            \         /
+     \     /                \      /
+      \  /         F1         \   /
+       \/_______________________\/
+      A \                       / B
+         \       F3            /
+          \                   /
+           \                 /
+            \               /
+             \             /
+              \           /
+               \         /
+                   \/
+                    1
+
+
+Draw orders: 
+F1: ABC x3,x4,x5
+F2: 0AC x0,x3,x5
+F3: 1BA x1,x4,x3
+F4: 2CB x2,x5,x4
+
+0: x0
+1: x1
+2: x2
+A: x3
+B: x4 
+C: x5
+*/
+			if (doUvs) {
+			    uv = oldUvs[i];
+			    x0 = uv[0];
+			    x1 = uv[1];
+			    x2 = uv[2];
+
+			    x3.set(midpoint(x0.x, x1.x), midpoint(x0.y, x1.y));
+			    x4.set(midpoint(x1.x, x2.x), midpoint(x1.y, x2.y));
+			    x5.set(midpoint(x0.x, x2.x), midpoint(x0.y, x2.y));
+			    newUv(newUVs, x3, x4, x5);
+			    newUv(newUVs, x0, x3, x5);
+
+			    newUv(newUVs, x1, x4, x3);
+			    newUv(newUVs, x2, x5, x4);
+			}
 		}
 
 		// Overwrite old arrays
 		geometry.vertices = newVertices;
 		geometry.faces = newFaces;
-
+        if(doUvs)
+		    geometry.faceVertexUvs[0] = newUVs;
 		// console.log('done');
 
 	};