three.js/examples/js/modifiers/BufferSubdivisionModifier.js

/*
 *	@author zz85 / http://twitter.com/blurspline / http://www.lab4games.net/zz85/blog 
 *	@author Matthew Adams / http://www.centerionware.com - added UV support and rewrote to use buffergeometry.
 *
 *	Subdivision Geometry Modifier 
 *		using Loop Subdivision Scheme for Geometry / BufferGeometry
 *
 *	References:
 *		http://graphics.stanford.edu/~mdfisher/subdivision.html
 *		http://www.holmes3d.net/graphics/subdivision/
 *		http://www.cs.rutgers.edu/~decarlo/readings/subdiv-sg00c.pdf
 *
 *	Known Issues:
 *		- currently doesn't handle "Sharp Edges"
 *      - no checks to prevent breaking when uv's don't exist.
 *      - vertex colors are unsupported.
 *     **DDS Images when using corrected uv's passed to subdivision modifier will have their uv's flipy'd within the correct uv set
 *     **Either flipy the DDS image, or use shaders. Don't try correcting the uv's before passing into subdiv (eg: v=1-v).
 *
 * @input THREE.Geometry, or index'd THREE.BufferGeometry with faceUV's (Not vertex uv's)
 * @output non-indexed vertex points, uv's, normals.
 *     
 */

/*
 *
 * The TypedArrayHelper class is designed to assist managing typed arrays, and to allow the removal of all 'new Vector3, new Face3, new Vector2'.
 * 
 * It will automatically resize them if trying to push a new element to an array that isn't long enough
 * It provides 'registers' that the units can be mapped to. This allows a small set of objects
 * (ex: vector3's, face3's, vector2's) to be allocated then used, to eliminate any need to rewrite all
 * the features those classes offer while not requiring some_huge_number to be allocated.
 * It should be moved into it's own file honestly, then included before the BufferSubdivisionModifier - maybe in three's core?
 *
 *
 * EX: new TypedArrayHelper(initial_size_in_elements, 3, THREE.Vector3, Float32Array, 3, ['x', 'y', 'z']); (the x,y,z comes from THREE.Vector3. It would be abc if it were a face3. etc etc)
 *
 */
THREE.Face3.prototype.set = function (a, b, c) {
    this.a = a;
    this.b = b;
    this.c = c;
}
var TypedArrayHelper = function (size, registers, register_type, array_type, unit_size, accessors) {
    this.array_type = array_type;
    this.register_type = register_type;
    this.unit_size = unit_size;
    this.accessors = accessors;
    this.buffer = new array_type(size * unit_size);
    this.register = [];
    this.length = 0;
    this.real_length = size;
    this.available_registers = registers;
    for (var i = 0; i < registers; i++) { this.register.push(new register_type()); }
}
TypedArrayHelper.prototype = {
    constructor: TypedArrayHelper,
    index_to_register: function (index, register, isLoop) {
        var base = index * this.unit_size;
        if (register >= this.available_registers) {
            throw ("Nope nope nope, not enough registers!");
        }
        if (index > this.length) {
            throw ("Nope nope nope, index is out of range");
        }
        for (var i = 0; i < this.unit_size; i++)
            (this.register[register])[this.accessors[i]] = this.buffer[base + i];

    },
    resize: function (new_size) {
        if (new_size == 0) new_size = 8;
        if (new_size < this.length) {
            this.buffer = this.buffer.subarray(0, this.length * this.unit_size);
        } else {
            if (this.buffer.length < new_size * this.unit_size) {
                var nBuffer = new this.array_type(new_size * this.unit_size);
                nBuffer.set(this.buffer);
                this.buffer = nBuffer;
                this.real_length = new_size;
            } else {
                var nBuffer = new this.array_type(new_size * this.unit_size);
                nBuffer.set(this.buffer.subarray(0, this.length * this.unit_size));
                this.buffer = nBuffer;
                this.real_length = new_size;
            }
        }
    },
    from_existing: function (oldArray) {
        var new_size = oldArray.length;
        this.buffer = new this.array_type(new_size);//this.resize(oldArray.length);
        this.buffer.set(oldArray);//.slice(0, oldArray.length));
        this.length = oldArray.length / this.unit_size;
        this.real_length = this.length;
    },
    push_element: function (vector) {
        if (this.length + 1 > this.real_length) { this.resize(this.real_length * 2); }
        var bpos = this.length * this.unit_size;
        for (var i = 0; i < this.unit_size; i++) {
            this.buffer[bpos + i] = vector[this.accessors[i]];
        }
        this.length++;
    },
    trim_size: function () {
        if (this.length < this.real_length) this.resize(this.length);
    },
    each: function (function_pointer, xtra) {
        if (typeof this.loop_register == 'undefined') this.loop_register = new this.register_type();
        for (var i = 0; i < this.length; i++) {
            for (var j = 0; j < this.unit_size; j++)
                this.loop_register[this.accessors[j]] = this.buffer[i * this.unit_size + j];
            function_pointer(this.loop_register, i, xtra);
        }
    },
    push_array: function (vector) {
        if (this.length + 1 > this.real_length) { this.resize(this.real_length * 2); }
        var bpos = this.length * this.unit_size;
        for (var i = 0; i < this.unit_size; i++) {
            this.buffer[bpos + i] = vector[i];
        }
        this.length++;
    }
}


function convertGeometryToIndexedBuffer(geometry) {
    var BGeom = new THREE.BufferGeometry();
    // create a new typed array
    var vertArray = new TypedArrayHelper(geometry.vertices.length, 0, THREE.Vector3, Float32Array, 3, ['x', 'y', 'z']);
    var indexArray = new TypedArrayHelper(geometry.faces.length, 0, THREE.Face3, Uint32Array, 3, ['a', 'b', 'c']);
    var uvArray = new TypedArrayHelper(geometry.faceVertexUvs[0].length * 3 * 3, 0, THREE.Vector2, Float32Array, 2, ['x', 'y']);

    var i, il;
    for (i = 0, il = geometry.vertices.length; i < il; i++) vertArray.push_element(geometry.vertices[i]);
    for (i = 0, il = geometry.faces.length; i < il; i++) indexArray.push_element(geometry.faces[i]);
    for (i = 0, il = geometry.faceVertexUvs[0].length; i < il; i++) {
        uvArray.push_element(geometry.faceVertexUvs[0][i][0]);
        uvArray.push_element(geometry.faceVertexUvs[0][i][1]);
        uvArray.push_element(geometry.faceVertexUvs[0][i][2]);
    }
    indexArray.trim_size();
    vertArray.trim_size();
    uvArray.trim_size();
    BGeom.setIndex(new THREE.BufferAttribute(indexArray.buffer,3));
    BGeom.addAttribute('position', new THREE.BufferAttribute(vertArray.buffer, 3));
    BGeom.addAttribute('uv', new THREE.BufferAttribute(uvArray.buffer, 2));
    return BGeom;
}
function addNormal(old, newn) {
   // old.x += newn.x;
   // old.y += newn.y;
   // old.z += newn.z;
    ///*
    if (old.x == 0) old.x = newn.x;
    else old.x = (old.x + newn.x) / 2;
    if (old.y == 0) old.y = newn.y;
    else old.y = (old.y + newn.y) / 2;
    if (old.z == 0) old.z = newn.z;
    else old.z = (old.z + newn.z) / 2;
   // */
}
function findArea(a, b, c) {
    return Math.abs(((a.x * (b.y - c.y)) + (b.x * (c.y - a.y)) + (c.x * (a.y - b.y))) / 2.0);
}
function find_angle3d(A, B, C) {
    var AB = Math.sqrt(Math.pow(B.x - A.x, 2) + Math.pow(B.y - A.y, 2));
    var BC = Math.sqrt(Math.pow(B.x - C.x, 2) + Math.pow(B.y - C.y, 2));
    var AC = Math.sqrt(Math.pow(C.x - A.x, 2) + Math.pow(C.y - A.y, 2));
    return Math.acos((BC * BC + AB * AB - AC * AC) / (2 * BC * AB));
}
function find_angle2d(p1,p2) {
    return Math.atan2(p2.y - p1.y, p2.x - p1.x);
}
function compute_vertex_normals(geometry) {
    var ABC = ['a', 'b', 'c'];
    var XYZ = ['x', 'y', 'z'];
    var XY = ['x', 'y'];
    var oldVertices = new TypedArrayHelper(0, 5, THREE.Vector3, Float32Array, 3, XYZ);
    var oldFaces = new TypedArrayHelper(0, 3, THREE.Face3, Uint32Array, 3, ABC);
    oldVertices.from_existing(geometry.getAttribute('position').array);
    var newNormals = new TypedArrayHelper(oldVertices.length * 3, 4, THREE.Vector3, Float32Array, 3, XYZ);
    
    var newNormalFaces = new TypedArrayHelper(oldVertices.length, 1, function () { this.x = 0; }, Float32Array, 1, ['x']);
    
    newNormals.length = oldVertices.length;
    var a, b, c;
    oldFaces.from_existing(geometry.index.array);
    var j, jl;
    var k,l;
    var my_weight;
    var full_weights = [0.0,0.0,0.0];

    for (var i = 0, il = oldFaces.length; i < il; i++) {
        oldFaces.index_to_register(i, 0);
        oldVertices.index_to_register(oldFaces.register[0].a, 0);
        oldVertices.index_to_register(oldFaces.register[0].b, 1);
        oldVertices.index_to_register(oldFaces.register[0].c, 2);
        newNormals.register[0].subVectors(oldVertices.register[1], oldVertices.register[0]);
        newNormals.register[1].subVectors(oldVertices.register[2], oldVertices.register[1]);
        newNormals.register[0].cross(newNormals.register[1]);
        my_weight = Math.abs(newNormals.register[0].length());
        //my_weight = findArea(oldVertices.register[0], oldVertices.register[1], oldVertices.register[2]);
        newNormalFaces.buffer[oldFaces.register[0].a] += my_weight;
        newNormalFaces.buffer[oldFaces.register[0].b] += my_weight;
        newNormalFaces.buffer[oldFaces.register[0].c] += my_weight;
    }
    var tmpx;
    var tmpy;
    var tmpz;
    var t_len;
    for (var i = 0, il = oldFaces.length; i < il; i++) {
        oldFaces.index_to_register(i, 0);
        oldVertices.index_to_register(oldFaces.register[0].a, 0);
        oldVertices.index_to_register(oldFaces.register[0].b, 1);
        oldVertices.index_to_register(oldFaces.register[0].c, 2);

        newNormals.register[0].subVectors(oldVertices.register[1], oldVertices.register[0]);
        newNormals.register[1].subVectors(oldVertices.register[2], oldVertices.register[0]);
/*
      //  newNormals.register[0].cross(newNormals.register[1]);

        newNormals.register[3].copy(newNormals.register[0]);//(a, b, c);

        t_len = (newNormals.register[3].x + newNormals.register[3].y + newNormals.register[3].z);
        newNormals.register[3].x = newNormals.register[3].x / t_len;
        newNormals.register[3].y = newNormals.register[3].y / t_len;
        newNormals.register[3].z = newNormals.register[3].z / t_len;
*/
        newNormals.register[3].set(0,0,0);
        newNormals.register[3].x = (newNormals.register[0].y*newNormals.register[1].z )-(newNormals.register[0].z*newNormals.register[1].y);
        newNormals.register[3].y = (newNormals.register[0].z*newNormals.register[1].x )-(newNormals.register[0].x*newNormals.register[1].z);
        newNormals.register[3].z = (newNormals.register[0].x*newNormals.register[1].y )-(newNormals.register[0].y*newNormals.register[1].x);
         
	newNormals.register[0].cross(newNormals.register[1]);



        my_weight = Math.abs(newNormals.register[0].length() );
       // oldVertices.register[3].subVectors(oldVertices.register[2],oldVertices.register[0]);
       // oldVertices.register[4].subVectors(oldVertices.register[2],oldVertices.register[1]);
       // var angle = find_angle2d(oldVertices.register[3],oldVertices.register[4]);
        full_weights[0] = (my_weight / newNormalFaces.buffer[oldFaces.register[0].a]) ;
        full_weights[1] = (my_weight / newNormalFaces.buffer[oldFaces.register[0].b]) ;
        full_weights[2] = (my_weight / newNormalFaces.buffer[oldFaces.register[0].c]) ;
        tmpx = newNormals.register[3].x * full_weights[0];
        tmpy = newNormals.register[3].y * full_weights[0];
        tmpz = newNormals.register[3].z * full_weights[0];
        
        newNormals.buffer[ oldFaces.register[0].a * 3     ] += newNormals.register[3].x * full_weights[0];
        newNormals.buffer[(oldFaces.register[0].a * 3) + 1] += newNormals.register[3].y * full_weights[0];
        newNormals.buffer[(oldFaces.register[0].a * 3) + 2] += newNormals.register[3].z * full_weights[0];

        newNormals.buffer[ oldFaces.register[0].b * 3     ] += newNormals.register[3].x * full_weights[1];
        newNormals.buffer[(oldFaces.register[0].b * 3) + 1] += newNormals.register[3].y * full_weights[1];
        newNormals.buffer[(oldFaces.register[0].b * 3) + 2] += newNormals.register[3].z * full_weights[1];

        newNormals.buffer[ oldFaces.register[0].c * 3     ] += newNormals.register[3].x * full_weights[2];
        newNormals.buffer[(oldFaces.register[0].c * 3) + 1] += newNormals.register[3].y * full_weights[2];
        newNormals.buffer[(oldFaces.register[0].c * 3) + 2] += newNormals.register[3].z * full_weights[2];
/*

        newNormals.index_to_register(oldFaces.register[0].a, 0);
        newNormals.index_to_register(oldFaces.register[0].b, 1);
        newNormals.index_to_register(oldFaces.register[0].c, 2);

        addNormal(newNormals.register[3], newNormals.register[0]);
        addNormal(newNormals.register[3], newNormals.register[1]);
        addNormal(newNormals.register[3], newNormals.register[2]);

        newNormals.buffer[oldFaces.register[0].a * 3] = newNormals.register[3].x;
        newNormals.buffer[(oldFaces.register[0].a * 3)+1] = newNormals.register[3].y;
        newNormals.buffer[(oldFaces.register[0].a * 3) + 2] = newNormals.register[3].z;

        newNormals.buffer[oldFaces.register[0].b * 3] = newNormals.register[3].x;
        newNormals.buffer[(oldFaces.register[0].b * 3) + 1] = newNormals.register[3].y;
        newNormals.buffer[(oldFaces.register[0].b * 3) + 2] = newNormals.register[3].z;

        newNormals.buffer[oldFaces.register[0].c * 3] = newNormals.register[3].x;
        newNormals.buffer[(oldFaces.register[0].c * 3) + 1] = newNormals.register[3].y;
        newNormals.buffer[(oldFaces.register[0].c * 3) + 2] = newNormals.register[3].z;
        */
      //  newNormalFaces[oldFaces.register[0].a] += 1;
    //    newNormalFaces[oldFaces.register[0].b] += 1;
     //   newNormalFaces[oldFaces.register[0].c] += 1;

    }
   // for (var i = 0, il = newNormalFaces.length; i < i; i++) {
   //     newNormals.buffer[(i * 3)] = newNormals.buffer[(i * 3)] / newNormalFaces.buffer[i];
  //      newNormals.buffer[(i * 3)+1] = newNormals.buffer[(i * 3)+1] / newNormalFaces.buffer[i];
   //     newNormals.buffer[(i * 3)+2] = newNormals.buffer[(i * 3)+2] / newNormalFaces.buffer[i];

    // }
    newNormals.trim_size();
    geometry.addAttribute('normal', new THREE.BufferAttribute(newNormals.buffer, 3));
}
function unIndexIndexedGeometry(geometry) {
    
    var ABC = ['a', 'b', 'c'];
    var XYZ = ['x', 'y', 'z'];
    var XY = ['x', 'y'];


    var oldVertices = new TypedArrayHelper(0, 3, THREE.Vector3, Float32Array, 3, XYZ);
    var oldFaces = new TypedArrayHelper(0, 3, THREE.Face3, Uint32Array, 3, ABC);
    var oldUvs = new TypedArrayHelper(0, 3, THREE.Vector2, Float32Array, 2, XY);
    var oldNormals = new TypedArrayHelper(0, 3, THREE.Vector3, Float32Array, 3, XYZ);
    oldVertices.from_existing(geometry.getAttribute('position').array);
    oldFaces.from_existing(geometry.index.array);
    oldUvs.from_existing(geometry.getAttribute('uv').array);
   // geometry.computeFaceNormals();
    // geometry.computeVertexNormals();
    compute_vertex_normals(geometry);
    oldNormals.from_existing(geometry.getAttribute('normal').array);

    var newVertices = new TypedArrayHelper(oldFaces.length * 3, 3, THREE.Vector3, Float32Array, 3, XYZ);
    var newNormals = new TypedArrayHelper(oldFaces.length * 3, 3, THREE.Vector3, Float32Array, 3, XYZ);
    var newUvs = new TypedArrayHelper(oldFaces.length * 3, 3, THREE.Vector2, Float32Array, 2, XY);
    var v, w;
    for (var i = 0, il = oldFaces.length; i < il; i++) {
        oldFaces.index_to_register(i, 0);
        oldVertices.index_to_register(oldFaces.register[0].a, 0);
        oldVertices.index_to_register(oldFaces.register[0].b, 1);
        oldVertices.index_to_register(oldFaces.register[0].c, 2);

        newVertices.push_element(oldVertices.register[0]);
        newVertices.push_element(oldVertices.register[1]);
        newVertices.push_element(oldVertices.register[2]);
        if (oldUvs.length != 0) {
            oldUvs.index_to_register((i * 3) + 0, 0);
            oldUvs.index_to_register((i * 3) + 1, 1);
            oldUvs.index_to_register((i * 3) + 2, 2);

            newUvs.push_element(oldUvs.register[0]);
            newUvs.push_element(oldUvs.register[1]);
            newUvs.push_element(oldUvs.register[2]);
        }
        oldNormals.index_to_register(oldFaces.register[0].a, 0);
        oldNormals.index_to_register(oldFaces.register[0].b, 1);
        oldNormals.index_to_register(oldFaces.register[0].c, 2);

        newNormals.push_element(oldNormals.register[0]);
        newNormals.push_element(oldNormals.register[1]);
        newNormals.push_element(oldNormals.register[2]);
        
     /*   oldVertices.index_to_register(oldFaces.register[0].a, 0);
        oldVertices.index_to_register(oldFaces.register[0].b, 1);
        oldVertices.index_to_register(oldFaces.register[0].c, 2);
        newNormals.register[0].subVectors(oldVertices.register[1], oldVertices.register[0]);
        newNormals.register[1].subVectors(oldVertices.register[2], oldVertices.register[0]);
        v = newNormals.register[0];
        w = newNormals.register[1];
        newNormals.register[2].x = (v.y * w.z) - (v.z * w.y);
        newNormals.register[2].y = (v.z * w.x) - (v.x * w.z)
        newNormals.register[2].z = (v.x * w.y) - (v.y * w.x)
        newNormals.push_element(newNormals.register[2]);
        newNormals.push_element(newNormals.register[2]);
        newNormals.push_element(newNormals.register[2]);?*/

    }
    newVertices.trim_size();
    newUvs.trim_size();
    newNormals.trim_size();
    geometry.index = null;
    geometry.addAttribute('position', new THREE.BufferAttribute(newVertices.buffer, 3));
    geometry.addAttribute('normal', new THREE.BufferAttribute(newNormals.buffer, 3));
    if(newUvs.length != 0)
        geometry.addAttribute('uv', new THREE.BufferAttribute(newUvs.buffer, 2));
  //  geometry.computeVertexNormals();
    return geometry;
}
THREE.BufferSubdivisionModifier = function (subdivisions) {

    this.subdivisions = (subdivisions === undefined) ? 1 : subdivisions;
    //this.subdivisions = 3;

};

// Applies the "modify" pattern
THREE.BufferSubdivisionModifier.prototype.modify = function (geometry) {
    
    if (geometry instanceof THREE.Geometry) {
        geometry.mergeVertices();
        if (typeof (geometry.normals) == 'undefined') geometry.normals = [];
            var BGEom = convertGeometryToIndexedBuffer(geometry);
            geometry = BGEom;
        } else if( !(geometry instanceof THREE.BufferGeometry) ) console.log("Geometry is not an instance of THREE.BufferGeometry or THREE.Geometry");
    
    var repeats = this.subdivisions;

    while (repeats-- > 0) {

        this.smooth(geometry);

    }

    return unIndexIndexedGeometry(geometry); // it doesn't change what geometry points to in the function that calls this.. >_<. how annoying.

};
var edge_type = function (a, b) {
    this.a = a;
    this.b = b;
    this.faces = [];
    this.newEdge = null;
};

(function () {

    // Some constants
    var WARNINGS = ! true; // Set to true for development
    var ABC = ['a', 'b', 'c'];
    var XYZ = ['x', 'y', 'z'];
    var XY = ['x', 'y'];

    function getEdge(a, b, map) {
        var key = Math.min(a, b) + "_" + Math.max(a, b);
        return map[key];

    }


    function processEdge(a, b, vertices, map, face, metaVertices) {

        var vertexIndexA = Math.min(a, b);
        var vertexIndexB = Math.max(a, b);

        var key = vertexIndexA + "_" + vertexIndexB;

        var edge;

        if (key in map) {

            edge = map[key];

        } else {

          //  var vertexA = vertices[vertexIndexA];
          //  var vertexB = vertices[vertexIndexB];

            edge = new edge_type(vertexIndexA,vertexIndexB);

            map[key] = edge;

        }

        edge.faces.push(face);

        metaVertices[a].edges.push(edge);
        metaVertices[b].edges.push(edge);


    }

    function generateLookups(vertices, faces, metaVertices, edges) {
        var i, il, face, edge;

        for (i = 0, il = vertices.length; i < il; i++) {
            metaVertices[i] = { edges: [] };
        }

        for (i = 0, il = faces.length; i < il; i++) {
            faces.index_to_register(i, 0);
            face = faces.register[0]; // Faces is now a TypedArrayHelper class, not a face3.

            processEdge(face.a, face.b, vertices, edges, i, metaVertices);
            processEdge(face.b, face.c, vertices, edges, i, metaVertices);
            processEdge(face.c, face.a, vertices, edges, i, metaVertices);

        }

    }

    function newFace(newFaces, face) {
        newFaces.push_element(face);
    }
    function midpoint(a, b) {
        return (Math.abs(b - a) / 2) + Math.min(a, b);
    }
    function newUv(newUvs, a, b, c) {
        newUvs.push_element(a);
        newUvs.push_element(b);
        newUvs.push_element(c);
    }

    /////////////////////////////

    // Performs one iteration of Subdivision
    THREE.BufferSubdivisionModifier.prototype.smooth = function (geometry) {
        var oldVertices, oldFaces, oldUvs;
        var newVertices, newFaces, newUVs;

        var n, l, i, il, j, k;
        var metaVertices, sourceEdges;

        // new stuff.
        var sourceEdges;


        oldVertices = new TypedArrayHelper(0, 3, THREE.Vector3, Float32Array, 3, XYZ);
        oldFaces = new TypedArrayHelper(0, 3, THREE.Face3, Uint32Array, 3, ABC);
        oldUvs = new TypedArrayHelper(0, 3, THREE.Vector2, Float32Array, 2, XY);
        oldVertices.from_existing(geometry.getAttribute('position').array);
        oldFaces.from_existing(geometry.index.array);
        oldUvs.from_existing(geometry.getAttribute('uv').array);

        var doUvs = false;
        if (typeof (oldUvs) != 'undefined' && oldUvs.length != 0) doUvs = true;
        /******************************************************
		 *
		 * Step 0: Preprocess Geometry to Generate edges Lookup
		 *
		 *******************************************************/

        metaVertices = new Array(oldVertices.length);
        sourceEdges = {}; // Edge => { oldVertex1, oldVertex2, faces[]  }

        generateLookups(oldVertices, oldFaces, metaVertices, sourceEdges);


        /******************************************************
		 *
		 *	Step 1. 
		 *	For each edge, create a new Edge Vertex,
		 *	then position it.
		 *
		 *******************************************************/

        newVertices = new TypedArrayHelper((geometry.getAttribute('position').array.length*2)/3, 2, THREE.Vector3, Float32Array, 3, XYZ);
        var other, currentEdge, newEdge, face;
        var edgeVertexWeight, adjacentVertexWeight, connectedFaces;

        var tmp = newVertices.register[1];
        for (i in sourceEdges) {

            currentEdge = sourceEdges[i];
            newEdge = newVertices.register[0];

            edgeVertexWeight = 3 / 8;
            adjacentVertexWeight = 1 / 8;

            connectedFaces = currentEdge.faces.length;

            // check how many linked faces. 2 should be correct.
            if (connectedFaces != 2) {

                // if length is not 2, handle condition
                edgeVertexWeight = 0.5;
                adjacentVertexWeight = 0;

                if (connectedFaces != 1) {

                    if (WARNINGS) console.warn('Subdivision Modifier: Number of connected faces != 2, is: ', connectedFaces, currentEdge);

                }

            }
            oldVertices.index_to_register(currentEdge.a, 0);
            oldVertices.index_to_register(currentEdge.b, 1);
            newEdge.addVectors(oldVertices.register[0], oldVertices.register[1]).multiplyScalar(edgeVertexWeight);

            tmp.set(0, 0, 0);

            for (j = 0; j < connectedFaces; j++) {
                oldFaces.index_to_register(currentEdge.faces[j], 0);
                face = oldFaces.register[0];

                for (k = 0; k < 3; k++) {
                    oldVertices.index_to_register(face[ABC[k]], 2);
                    other = oldVertices.register[2];
                    if (face[ABC[k]] !== currentEdge.a && face[ABC[k]] !== currentEdge.b) break;
                }

                tmp.add(other);

            }

            tmp.multiplyScalar(adjacentVertexWeight);
            newEdge.add(tmp);

            currentEdge.newEdge = newVertices.length;
            newVertices.push_element(newEdge);

            // console.log(currentEdge, newEdge);

        }
        var edgeLength = newVertices.length;
        /******************************************************
		 *
		 *	Step 2. 
		 *	Reposition each source vertices.
		 *
		 *******************************************************/

        var beta, sourceVertexWeight, connectingVertexWeight;
        var connectingEdge, connectingEdges, oldVertex, newSourceVertex;
        for (i = 0, il = oldVertices.length; i < il; i++) {
            oldVertices.index_to_register(i, 0, XYZ);
            oldVertex = oldVertices.register[0];

            // find all connecting edges (using lookupTable)
            connectingEdges = metaVertices[i].edges;
            n = connectingEdges.length;
            

            if (n == 3) {

                beta = 3 / 16;

            } else if (n > 3) {

                beta = 3 / (8 * n); // Warren's modified formula

            }

            // Loop's original beta formula
            // beta = 1 / n * ( 5/8 - Math.pow( 3/8 + 1/4 * Math.cos( 2 * Math. PI / n ), 2) );

            sourceVertexWeight = 1 - n * beta;
            connectingVertexWeight = beta;

            if (n <= 2) {

                // crease and boundary rules
                // console.warn('crease and boundary rules');

                if (n == 2) {

                    if (WARNINGS) console.warn('2 connecting edges', connectingEdges);
                    sourceVertexWeight = 3 / 4;
                    connectingVertexWeight = 1 / 8;

                    // sourceVertexWeight = 1;
                    // connectingVertexWeight = 0;

                } else if (n == 1) {

                    if (WARNINGS) console.warn('only 1 connecting edge');

                } else if (n == 0) {

                    if (WARNINGS) console.warn('0 connecting edges');

                }

            }

            newSourceVertex = oldVertex.multiplyScalar(sourceVertexWeight);

            tmp.set(0, 0, 0);

            for (j = 0; j < n; j++) {

                connectingEdge = connectingEdges[j];
                other = connectingEdge.a !== i ? connectingEdge.a : connectingEdge.b;
                oldVertices.index_to_register(other, 1, XYZ);
                tmp.add(oldVertices.register[1]);

            }

            tmp.multiplyScalar(connectingVertexWeight);
            newSourceVertex.add(tmp);

            newVertices.push_element(newSourceVertex,XYZ);

        }


        /******************************************************
		 *
		 *	Step 3. 
		 *	Generate Faces between source vertecies
		 *	and edge vertices.
		 *
		 *******************************************************/

      
        var edge1, edge2, edge3;
        newFaces = new TypedArrayHelper((geometry.index.array.length*4) / 3, 1, THREE.Face3, Float32Array, 3, ABC);
        newUVs = new TypedArrayHelper((geometry.getAttribute('uv').array.length * 4) / 2, 3, THREE.Vector2, Float32Array, 2, XY);
        var x3 = newUVs.register[0];
        var x4 = newUVs.register[1];
        var x5 = newUVs.register[2];
        var tFace = newFaces.register[0];
        for (i = 0, il = oldFaces.length; i < il; i++) {
            oldFaces.index_to_register(i, 0);
            face = oldFaces.register[0];//oldFaces[i];

            // find the 3 new edges vertex of each old face
            // The new source verts are added after the new edge verts now.. 
            edge1 = getEdge(face.a, face.b, sourceEdges).newEdge;
            edge2 = getEdge(face.b, face.c, sourceEdges).newEdge;
            edge3 = getEdge(face.c, face.a, sourceEdges).newEdge;

            // create 4 faces.
            tFace.set(edge1, edge2, edge3);
            newFace(newFaces, tFace);
            tFace.set(face.a + edgeLength, edge1, edge3);
            newFace(newFaces, tFace);
            tFace.set(face.b + edgeLength,edge2,edge1);
            newFace(newFaces, tFace);
            tFace.set(face.c + edgeLength,edge3,edge2);
            newFace(newFaces, tFace);
            // 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) {

                oldUvs.index_to_register(i * 3, 0);
                oldUvs.index_to_register((i * 3)+1, 1);
                oldUvs.index_to_register((i * 3)+2, 2);

              //  uv = oldUvs[i];
                x0 = oldUvs.register[0];//uv[0];
                x1 = oldUvs.register[1];//uv[1];
                x2 = oldUvs.register[2];//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.addAttribute('position', THREE.BufferAttribute(newVertices, 3).copy)
        newVertices.trim_size();
        newFaces.trim_size();
        newUVs.trim_size();
        geometry.addAttribute('position', new THREE.BufferAttribute(newVertices.buffer,3));
        geometry.setIndex(new THREE.BufferAttribute(newFaces.buffer,3));
        geometry.addAttribute('uv', new THREE.BufferAttribute(newUVs.buffer,2));
        /*
        geometry.vertices = newVertices;
        geometry.faces = newFaces;
        geometry.faceVertexUvs[0] = newUVs; */
        // console.log('done');

    };


})();