You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
495 lines
9.5 KiB
495 lines
9.5 KiB
/*
|
|
* @author zz85 / http://twitter.com/blurspline / http://www.lab4games.net/zz85/blog
|
|
*
|
|
* Simplification Geometry Modifier
|
|
* - based on code and technique
|
|
* - by Stan Melax in 1998
|
|
* - Progressive Mesh type Polygon Reduction Algorithm
|
|
* - http://www.melax.com/polychop/
|
|
*/
|
|
|
|
THREE.SimplifyModifier = function () {};
|
|
|
|
( function () {
|
|
|
|
var cb = new THREE.Vector3(), ab = new THREE.Vector3();
|
|
|
|
function pushIfUnique( array, object ) {
|
|
|
|
if ( array.indexOf( object ) === - 1 ) array.push( object );
|
|
|
|
}
|
|
|
|
function removeFromArray( array, object ) {
|
|
|
|
var k = array.indexOf( object );
|
|
if ( k > - 1 ) array.splice( k, 1 );
|
|
|
|
}
|
|
|
|
function computeEdgeCollapseCost( u, v ) {
|
|
|
|
// if we collapse edge uv by moving u to v then how
|
|
// much different will the model change, i.e. the "error".
|
|
|
|
var edgelength = v.position.distanceTo( u.position );
|
|
var curvature = 0;
|
|
|
|
var sideFaces = [];
|
|
var i, il = u.faces.length, face, sideFace;
|
|
|
|
// find the "sides" triangles that are on the edge uv
|
|
for ( i = 0; i < il; i ++ ) {
|
|
|
|
face = u.faces[ i ];
|
|
|
|
if ( face.hasVertex( v ) ) {
|
|
|
|
sideFaces.push( face );
|
|
|
|
}
|
|
|
|
}
|
|
|
|
// use the triangle facing most away from the sides
|
|
// to determine our curvature term
|
|
for ( i = 0; i < il; i ++ ) {
|
|
|
|
var minCurvature = 1;
|
|
face = u.faces[ i ];
|
|
|
|
for ( var j = 0; j < sideFaces.length; j ++ ) {
|
|
|
|
sideFace = sideFaces[ j ];
|
|
// use dot product of face normals.
|
|
var dotProd = face.normal.dot( sideFace.normal );
|
|
minCurvature = Math.min( minCurvature, ( 1.001 - dotProd ) / 2 );
|
|
|
|
}
|
|
|
|
curvature = Math.max( curvature, minCurvature );
|
|
|
|
}
|
|
|
|
// crude approach in attempt to preserve borders
|
|
// though it seems not to be totally correct
|
|
var borders = 0;
|
|
if ( sideFaces.length < 2 ) {
|
|
|
|
// we add some arbitrary cost for borders,
|
|
// borders += 10;
|
|
curvature = 1;
|
|
|
|
}
|
|
|
|
var amt = edgelength * curvature + borders;
|
|
|
|
return amt;
|
|
|
|
}
|
|
|
|
function computeEdgeCostAtVertex( v ) {
|
|
|
|
// compute the edge collapse cost for all edges that start
|
|
// from vertex v. Since we are only interested in reducing
|
|
// the object by selecting the min cost edge at each step, we
|
|
// only cache the cost of the least cost edge at this vertex
|
|
// (in member variable collapse) as well as the value of the
|
|
// cost (in member variable collapseCost).
|
|
|
|
if ( v.neighbors.length === 0 ) {
|
|
|
|
// collapse if no neighbors.
|
|
v.collapseNeighbor = null;
|
|
v.collapseCost = - 0.01;
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
v.collapseCost = 100000;
|
|
v.collapseNeighbor = null;
|
|
|
|
// search all neighboring edges for "least cost" edge
|
|
for ( var i = 0; i < v.neighbors.length; i ++ ) {
|
|
|
|
var collapseCost = computeEdgeCollapseCost( v, v.neighbors[ i ] );
|
|
|
|
if ( ! v.collapseNeighbor ) {
|
|
|
|
v.collapseNeighbor = v.neighbors[ i ];
|
|
v.collapseCost = collapseCost;
|
|
v.minCost = collapseCost;
|
|
v.totalCost = 0;
|
|
v.costCount = 0;
|
|
|
|
}
|
|
|
|
v.costCount ++;
|
|
v.totalCost += collapseCost;
|
|
|
|
if ( collapseCost < v.minCost ) {
|
|
|
|
v.collapseNeighbor = v.neighbors[ i ];
|
|
v.minCost = collapseCost;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
// we average the cost of collapsing at this vertex
|
|
v.collapseCost = v.totalCost / v.costCount;
|
|
// v.collapseCost = v.minCost;
|
|
|
|
}
|
|
|
|
function removeVertex( v, vertices ) {
|
|
|
|
console.assert( v.faces.length === 0 );
|
|
|
|
while ( v.neighbors.length ) {
|
|
|
|
var n = v.neighbors.pop();
|
|
removeFromArray( n.neighbors, v );
|
|
|
|
}
|
|
|
|
removeFromArray( vertices, v );
|
|
|
|
}
|
|
|
|
function removeFace( f, faces ) {
|
|
|
|
removeFromArray( faces, f );
|
|
|
|
if ( f.v1 ) removeFromArray( f.v1.faces, f );
|
|
if ( f.v2 ) removeFromArray( f.v2.faces, f );
|
|
if ( f.v3 ) removeFromArray( f.v3.faces, f );
|
|
|
|
// TODO optimize this!
|
|
var vs = [ f.v1, f.v2, f.v3 ];
|
|
var v1, v2;
|
|
|
|
for ( var i = 0; i < 3; i ++ ) {
|
|
|
|
v1 = vs[ i ];
|
|
v2 = vs[ ( i + 1 ) % 3 ];
|
|
|
|
if ( ! v1 || ! v2 ) continue;
|
|
|
|
v1.removeIfNonNeighbor( v2 );
|
|
v2.removeIfNonNeighbor( v1 );
|
|
|
|
}
|
|
|
|
}
|
|
|
|
function collapse( vertices, faces, u, v ) { // u and v are pointers to vertices of an edge
|
|
|
|
// Collapse the edge uv by moving vertex u onto v
|
|
|
|
if ( ! v ) {
|
|
|
|
// u is a vertex all by itself so just delete it..
|
|
removeVertex( u, vertices );
|
|
return;
|
|
|
|
}
|
|
|
|
var i;
|
|
var tmpVertices = [];
|
|
|
|
for ( i = 0; i < u.neighbors.length; i ++ ) {
|
|
|
|
tmpVertices.push( u.neighbors[ i ] );
|
|
|
|
}
|
|
|
|
|
|
// delete triangles on edge uv:
|
|
for ( i = u.faces.length - 1; i >= 0; i -- ) {
|
|
|
|
if ( u.faces[ i ].hasVertex( v ) ) {
|
|
|
|
removeFace( u.faces[ i ], faces );
|
|
|
|
}
|
|
|
|
}
|
|
|
|
// update remaining triangles to have v instead of u
|
|
for ( i = u.faces.length - 1; i >= 0; i -- ) {
|
|
|
|
u.faces[ i ].replaceVertex( u, v );
|
|
|
|
}
|
|
|
|
|
|
removeVertex( u, vertices );
|
|
|
|
// recompute the edge collapse costs in neighborhood
|
|
for ( i = 0; i < tmpVertices.length; i ++ ) {
|
|
|
|
computeEdgeCostAtVertex( tmpVertices[ i ] );
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
function minimumCostEdge( vertices ) {
|
|
|
|
// O(n * n) approach. TODO optimize this
|
|
|
|
var least = vertices[ 0 ];
|
|
|
|
for ( var i = 0; i < vertices.length; i ++ ) {
|
|
|
|
if ( vertices[ i ].collapseCost < least.collapseCost ) {
|
|
|
|
least = vertices[ i ];
|
|
|
|
}
|
|
|
|
}
|
|
|
|
return least;
|
|
|
|
}
|
|
|
|
// we use a triangle class to represent structure of face slightly differently
|
|
|
|
function Triangle( v1, v2, v3, a, b, c ) {
|
|
|
|
this.a = a;
|
|
this.b = b;
|
|
this.c = c;
|
|
|
|
this.v1 = v1;
|
|
this.v2 = v2;
|
|
this.v3 = v3;
|
|
|
|
this.normal = new THREE.Vector3();
|
|
|
|
this.computeNormal();
|
|
|
|
v1.faces.push( this );
|
|
v1.addUniqueNeighbor( v2 );
|
|
v1.addUniqueNeighbor( v3 );
|
|
|
|
v2.faces.push( this );
|
|
v2.addUniqueNeighbor( v1 );
|
|
v2.addUniqueNeighbor( v3 );
|
|
|
|
|
|
v3.faces.push( this );
|
|
v3.addUniqueNeighbor( v1 );
|
|
v3.addUniqueNeighbor( v2 );
|
|
|
|
}
|
|
|
|
Triangle.prototype.computeNormal = function () {
|
|
|
|
var vA = this.v1.position;
|
|
var vB = this.v2.position;
|
|
var vC = this.v3.position;
|
|
|
|
cb.subVectors( vC, vB );
|
|
ab.subVectors( vA, vB );
|
|
cb.cross( ab ).normalize();
|
|
|
|
this.normal.copy( cb );
|
|
|
|
};
|
|
|
|
Triangle.prototype.hasVertex = function ( v ) {
|
|
|
|
return v === this.v1 || v === this.v2 || v === this.v3;
|
|
|
|
};
|
|
|
|
Triangle.prototype.replaceVertex = function ( oldv, newv ) {
|
|
|
|
if ( oldv === this.v1 ) this.v1 = newv;
|
|
else if ( oldv === this.v2 ) this.v2 = newv;
|
|
else if ( oldv === this.v3 ) this.v3 = newv;
|
|
|
|
removeFromArray( oldv.faces, this );
|
|
newv.faces.push( this );
|
|
|
|
|
|
oldv.removeIfNonNeighbor( this.v1 );
|
|
this.v1.removeIfNonNeighbor( oldv );
|
|
|
|
oldv.removeIfNonNeighbor( this.v2 );
|
|
this.v2.removeIfNonNeighbor( oldv );
|
|
|
|
oldv.removeIfNonNeighbor( this.v3 );
|
|
this.v3.removeIfNonNeighbor( oldv );
|
|
|
|
this.v1.addUniqueNeighbor( this.v2 );
|
|
this.v1.addUniqueNeighbor( this.v3 );
|
|
|
|
this.v2.addUniqueNeighbor( this.v1 );
|
|
this.v2.addUniqueNeighbor( this.v3 );
|
|
|
|
this.v3.addUniqueNeighbor( this.v1 );
|
|
this.v3.addUniqueNeighbor( this.v2 );
|
|
|
|
this.computeNormal();
|
|
|
|
};
|
|
|
|
function Vertex( v, id ) {
|
|
|
|
this.position = v;
|
|
|
|
this.id = id; // old index id
|
|
|
|
this.faces = []; // faces vertex is connected
|
|
this.neighbors = []; // neighbouring vertices aka "adjacentVertices"
|
|
|
|
// these will be computed in computeEdgeCostAtVertex()
|
|
this.collapseCost = 0; // cost of collapsing this vertex, the less the better. aka objdist
|
|
this.collapseNeighbor = null; // best candinate for collapsing
|
|
|
|
}
|
|
|
|
Vertex.prototype.addUniqueNeighbor = function ( vertex ) {
|
|
|
|
pushIfUnique( this.neighbors, vertex );
|
|
|
|
};
|
|
|
|
Vertex.prototype.removeIfNonNeighbor = function ( n ) {
|
|
|
|
var neighbors = this.neighbors;
|
|
var faces = this.faces;
|
|
|
|
var offset = neighbors.indexOf( n );
|
|
if ( offset === - 1 ) return;
|
|
for ( var i = 0; i < faces.length; i ++ ) {
|
|
|
|
if ( faces[ i ].hasVertex( n ) ) return;
|
|
|
|
}
|
|
|
|
neighbors.splice( offset, 1 );
|
|
|
|
};
|
|
|
|
THREE.SimplifyModifier.prototype.modify = function ( geometry, count ) {
|
|
|
|
if ( geometry.isBufferGeometry ) {
|
|
|
|
geometry = new THREE.Geometry().fromBufferGeometry( geometry );
|
|
|
|
}
|
|
|
|
geometry.mergeVertices();
|
|
|
|
var oldVertices = geometry.vertices; // Three Position
|
|
var oldFaces = geometry.faces; // Three Face
|
|
|
|
// conversion
|
|
var vertices = [];
|
|
var faces = [];
|
|
|
|
var i, il;
|
|
|
|
//
|
|
// put data of original geometry in different data structures
|
|
//
|
|
|
|
// add vertices
|
|
|
|
for ( i = 0, il = oldVertices.length; i < il; i ++ ) {
|
|
|
|
var vertex = new Vertex( oldVertices[ i ], i );
|
|
vertices.push( vertex );
|
|
|
|
}
|
|
|
|
// add faces
|
|
|
|
for ( i = 0, il = oldFaces.length; i < il; i ++ ) {
|
|
|
|
var face = oldFaces[ i ];
|
|
|
|
var a = face.a;
|
|
var b = face.b;
|
|
var c = face.c;
|
|
|
|
var triangle = new Triangle( vertices[ a ], vertices[ b ], vertices[ c ], a, b, c );
|
|
faces.push( triangle );
|
|
|
|
}
|
|
|
|
// compute all edge collapse costs
|
|
|
|
for ( i = 0, il = vertices.length; i < il; i ++ ) {
|
|
|
|
computeEdgeCostAtVertex( vertices[ i ] );
|
|
|
|
}
|
|
|
|
var nextVertex;
|
|
|
|
var z = count;
|
|
|
|
while ( z -- ) {
|
|
|
|
nextVertex = minimumCostEdge( vertices );
|
|
|
|
if ( ! nextVertex ) {
|
|
|
|
console.log( 'THREE.SimplifyModifier: No next vertex' );
|
|
break;
|
|
|
|
}
|
|
|
|
collapse( vertices, faces, nextVertex, nextVertex.collapseNeighbor );
|
|
|
|
}
|
|
|
|
//
|
|
|
|
var simplifiedGeometry = new THREE.BufferGeometry();
|
|
var position = [];
|
|
var index = [];
|
|
|
|
//
|
|
|
|
for ( i = 0; i < vertices.length; i ++ ) {
|
|
|
|
var vertex = vertices[ i ].position;
|
|
position.push( vertex.x, vertex.y, vertex.z );
|
|
|
|
}
|
|
|
|
//
|
|
|
|
for ( i = 0; i < faces.length; i ++ ) {
|
|
|
|
var face = faces[ i ];
|
|
|
|
var a = vertices.indexOf( face.v1 );
|
|
var b = vertices.indexOf( face.v2 );
|
|
var c = vertices.indexOf( face.v3 );
|
|
|
|
index.push( a, b, c );
|
|
|
|
}
|
|
|
|
//
|
|
|
|
simplifiedGeometry.addAttribute( 'position', new THREE.Float32BufferAttribute( position, 3 ) );
|
|
simplifiedGeometry.setIndex( index );
|
|
|
|
return simplifiedGeometry;
|
|
|
|
};
|
|
|
|
} )();
|