fireball/lib/geometries/EdgesGeometry.js

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2018-12-25 13:59:22 +00:00
/**
* @author WestLangley / http://github.com/WestLangley
* @author Mugen87 / https://github.com/Mugen87
*/
import { BufferGeometry } from '../core/BufferGeometry.js';
import { Float32BufferAttribute } from '../core/BufferAttribute.js';
import { Geometry } from '../core/Geometry.js';
import { _Math } from '../math/Math.js';
function EdgesGeometry( geometry, thresholdAngle ) {
BufferGeometry.call( this );
this.type = 'EdgesGeometry';
this.parameters = {
thresholdAngle: thresholdAngle
};
thresholdAngle = ( thresholdAngle !== undefined ) ? thresholdAngle : 1;
// buffer
var vertices = [];
// helper variables
var thresholdDot = Math.cos( _Math.DEG2RAD * thresholdAngle );
var edge = [ 0, 0 ], edges = {}, edge1, edge2;
var key, keys = [ 'a', 'b', 'c' ];
// prepare source geometry
var geometry2;
if ( geometry.isBufferGeometry ) {
geometry2 = new Geometry();
geometry2.fromBufferGeometry( geometry );
} else {
geometry2 = geometry.clone();
}
geometry2.mergeVertices();
geometry2.computeFaceNormals();
var sourceVertices = geometry2.vertices;
var faces = geometry2.faces;
// now create a data structure where each entry represents an edge with its adjoining faces
for ( var i = 0, l = faces.length; i < l; i ++ ) {
var face = faces[ i ];
for ( var j = 0; j < 3; j ++ ) {
edge1 = face[ keys[ j ] ];
edge2 = face[ keys[ ( j + 1 ) % 3 ] ];
edge[ 0 ] = Math.min( edge1, edge2 );
edge[ 1 ] = Math.max( edge1, edge2 );
key = edge[ 0 ] + ',' + edge[ 1 ];
if ( edges[ key ] === undefined ) {
edges[ key ] = { index1: edge[ 0 ], index2: edge[ 1 ], face1: i, face2: undefined };
} else {
edges[ key ].face2 = i;
}
}
}
// generate vertices
for ( key in edges ) {
var e = edges[ key ];
// an edge is only rendered if the angle (in degrees) between the face normals of the adjoining faces exceeds this value. default = 1 degree.
if ( e.face2 === undefined || faces[ e.face1 ].normal.dot( faces[ e.face2 ].normal ) <= thresholdDot ) {
var vertex = sourceVertices[ e.index1 ];
vertices.push( vertex.x, vertex.y, vertex.z );
vertex = sourceVertices[ e.index2 ];
vertices.push( vertex.x, vertex.y, vertex.z );
}
}
// build geometry
this.addAttribute( 'position', new Float32BufferAttribute( vertices, 3 ) );
}
EdgesGeometry.prototype = Object.create( BufferGeometry.prototype );
EdgesGeometry.prototype.constructor = EdgesGeometry;
export { EdgesGeometry };