Doodle3D-Slicer/three.js-master/examples/js/modifiers/SubdivisionModifier.js
2015-06-12 15:58:26 +02:00

343 lines
7.9 KiB
JavaScript
Executable File

/*
* @author zz85 / http://twitter.com/blurspline / http://www.lab4games.net/zz85/blog
*
* Subdivision Geometry Modifier
* using Loop Subdivision Scheme
*
* 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 UVs
* - currently doesn't handle "Sharp Edges"
*
*/
THREE.SubdivisionModifier = function ( subdivisions ) {
this.subdivisions = (subdivisions === undefined ) ? 1 : subdivisions;
};
// Applies the "modify" pattern
THREE.SubdivisionModifier.prototype.modify = function ( geometry ) {
var repeats = this.subdivisions;
while ( repeats -- > 0 ) {
this.smooth( geometry );
}
delete geometry.__tmpVertices;
geometry.computeFaceNormals();
geometry.computeVertexNormals();
};
(function() {
// Some constants
var WARNINGS = !true; // Set to true for development
var ABC = [ 'a', 'b', 'c' ];
function getEdge( a, b, map ) {
var vertexIndexA = Math.min( a, b );
var vertexIndexB = Math.max( a, b );
var key = vertexIndexA + "_" + vertexIndexB;
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 = {
a: vertexA, // pointer reference
b: vertexB,
newEdge: null,
// aIndex: a, // numbered reference
// bIndex: b,
faces: [] // pointers to face
};
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 ++ ) {
face = faces[ i ];
processEdge( face.a, face.b, vertices, edges, face, metaVertices );
processEdge( face.b, face.c, vertices, edges, face, metaVertices );
processEdge( face.c, face.a, vertices, edges, face, metaVertices );
}
}
function newFace( newFaces, a, b, c ) {
newFaces.push( new THREE.Face3( a, b, c ) );
}
/////////////////////////////
// Performs one iteration of Subdivision
THREE.SubdivisionModifier.prototype.smooth = function ( geometry ) {
var tmp = new THREE.Vector3();
var oldVertices, oldFaces;
var newVertices, newFaces; // newUVs = [];
var n, l, i, il, j, k;
var metaVertices, sourceEdges;
// new stuff.
var sourceEdges, newEdgeVertices, newSourceVertices
oldVertices = geometry.vertices; // { x, y, z}
oldFaces = geometry.faces; // { a: oldVertex1, b: oldVertex2, c: oldVertex3 }
/******************************************************
*
* 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.
*
*******************************************************/
newEdgeVertices = [];
var other, currentEdge, newEdge, face;
var edgeVertexWeight, adjacentVertexWeight, connectedFaces;
for ( i in sourceEdges ) {
currentEdge = sourceEdges[ i ];
newEdge = new THREE.Vector3();
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);
}
}
newEdge.addVectors( currentEdge.a, currentEdge.b ).multiplyScalar( edgeVertexWeight );
tmp.set( 0, 0, 0 );
for ( j = 0; j < connectedFaces; j ++ ) {
face = currentEdge.faces[ j ];
for ( k = 0; k < 3; k ++ ) {
other = oldVertices[ face[ ABC[k] ] ];
if (other !== currentEdge.a && other !== currentEdge.b ) break;
}
tmp.add( other );
}
tmp.multiplyScalar( adjacentVertexWeight );
newEdge.add( tmp );
currentEdge.newEdge = newEdgeVertices.length;
newEdgeVertices.push(newEdge);
// console.log(currentEdge, newEdge);
}
/******************************************************
*
* Step 2.
* Reposition each source vertices.
*
*******************************************************/
var beta, sourceVertexWeight, connectingVertexWeight;
var connectingEdge, connectingEdges, oldVertex, newSourceVertex;
newSourceVertices = [];
for ( i = 0, il = oldVertices.length; i < il; i ++ ) {
oldVertex = oldVertices[ i ];
// find all connecting edges (using lookupTable)
connectingEdges = metaVertices[ i ].edges;
n = connectingEdges.length;
beta;
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.clone().multiplyScalar( sourceVertexWeight );
tmp.set( 0, 0, 0 );
for ( j = 0; j < n; j ++ ) {
connectingEdge = connectingEdges[ j ];
other = connectingEdge.a !== oldVertex ? connectingEdge.a : connectingEdge.b;
tmp.add( other );
}
tmp.multiplyScalar( connectingVertexWeight );
newSourceVertex.add( tmp );
newSourceVertices.push( newSourceVertex );
}
/******************************************************
*
* Step 3.
* Generate Faces between source vertecies
* and edge vertices.
*
*******************************************************/
newVertices = newSourceVertices.concat( newEdgeVertices );
var sl = newSourceVertices.length, edge1, edge2, edge3;
newFaces = [];
for ( i = 0, il = oldFaces.length; i < il; i ++ ) {
face = oldFaces[ i ];
// find the 3 new edges vertex of each old face
edge1 = getEdge( face.a, face.b, sourceEdges ).newEdge + sl;
edge2 = getEdge( face.b, face.c, sourceEdges ).newEdge + sl;
edge3 = getEdge( face.c, face.a, sourceEdges ).newEdge + sl;
// create 4 faces.
newFace( newFaces, edge1, edge2, edge3 );
newFace( newFaces, face.a, edge1, edge3 );
newFace( newFaces, face.b, edge2, edge1 );
newFace( newFaces, face.c, edge3, edge2 );
}
// Overwrite old arrays
geometry.vertices = newVertices;
geometry.faces = newFaces;
// console.log('done');
};
})();