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187 lines
3.6 KiB
187 lines
3.6 KiB
/**
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* @author mrdoob / http://mrdoob.com/
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*/
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THREE.BufferGeometryUtils = {
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computeTangents: function ( geometry ) {
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var index = geometry.index;
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var attributes = geometry.attributes;
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// based on http://www.terathon.com/code/tangent.html
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// (per vertex tangents)
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if ( index === null ||
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attributes.position === undefined ||
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attributes.normal === undefined ||
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attributes.uv === undefined ) {
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console.warn( 'THREE.BufferGeometry: Missing required attributes (index, position, normal or uv) in BufferGeometry.computeTangents()' );
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return;
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}
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var indices = index.array;
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var positions = attributes.position.array;
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var normals = attributes.normal.array;
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var uvs = attributes.uv.array;
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var nVertices = positions.length / 3;
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if ( attributes.tangent === undefined ) {
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geometry.addAttribute( 'tangent', new THREE.BufferAttribute( new Float32Array( 4 * nVertices ), 4 ) );
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}
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var tangents = attributes.tangent.array;
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var tan1 = [], tan2 = [];
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for ( var k = 0; k < nVertices; k ++ ) {
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tan1[ k ] = new THREE.Vector3();
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tan2[ k ] = new THREE.Vector3();
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}
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var vA = new THREE.Vector3(),
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vB = new THREE.Vector3(),
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vC = new THREE.Vector3(),
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uvA = new THREE.Vector2(),
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uvB = new THREE.Vector2(),
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uvC = new THREE.Vector2(),
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sdir = new THREE.Vector3(),
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tdir = new THREE.Vector3();
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function handleTriangle( a, b, c ) {
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vA.fromArray( positions, a * 3 );
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vB.fromArray( positions, b * 3 );
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vC.fromArray( positions, c * 3 );
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uvA.fromArray( uvs, a * 2 );
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uvB.fromArray( uvs, b * 2 );
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uvC.fromArray( uvs, c * 2 );
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var x1 = vB.x - vA.x;
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var x2 = vC.x - vA.x;
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var y1 = vB.y - vA.y;
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var y2 = vC.y - vA.y;
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var z1 = vB.z - vA.z;
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var z2 = vC.z - vA.z;
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var s1 = uvB.x - uvA.x;
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var s2 = uvC.x - uvA.x;
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var t1 = uvB.y - uvA.y;
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var t2 = uvC.y - uvA.y;
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var r = 1.0 / ( s1 * t2 - s2 * t1 );
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sdir.set(
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( t2 * x1 - t1 * x2 ) * r,
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( t2 * y1 - t1 * y2 ) * r,
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( t2 * z1 - t1 * z2 ) * r
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);
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tdir.set(
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( s1 * x2 - s2 * x1 ) * r,
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( s1 * y2 - s2 * y1 ) * r,
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( s1 * z2 - s2 * z1 ) * r
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);
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tan1[ a ].add( sdir );
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tan1[ b ].add( sdir );
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tan1[ c ].add( sdir );
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tan2[ a ].add( tdir );
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tan2[ b ].add( tdir );
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tan2[ c ].add( tdir );
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}
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var groups = geometry.groups;
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if ( groups.length === 0 ) {
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groups = [ {
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start: 0,
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count: indices.length
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} ];
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}
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for ( var j = 0, jl = groups.length; j < jl; ++ j ) {
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var group = groups[ j ];
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var start = group.start;
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var count = group.count;
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for ( var i = start, il = start + count; i < il; i += 3 ) {
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handleTriangle(
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indices[ i + 0 ],
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indices[ i + 1 ],
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indices[ i + 2 ]
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);
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}
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}
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var tmp = new THREE.Vector3(), tmp2 = new THREE.Vector3();
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var n = new THREE.Vector3(), n2 = new THREE.Vector3();
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var w, t, test;
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function handleVertex( v ) {
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n.fromArray( normals, v * 3 );
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n2.copy( n );
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t = tan1[ v ];
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// Gram-Schmidt orthogonalize
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tmp.copy( t );
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tmp.sub( n.multiplyScalar( n.dot( t ) ) ).normalize();
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// Calculate handedness
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tmp2.crossVectors( n2, t );
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test = tmp2.dot( tan2[ v ] );
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w = ( test < 0.0 ) ? - 1.0 : 1.0;
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tangents[ v * 4 ] = tmp.x;
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tangents[ v * 4 + 1 ] = tmp.y;
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tangents[ v * 4 + 2 ] = tmp.z;
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tangents[ v * 4 + 3 ] = w;
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}
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for ( var j = 0, jl = groups.length; j < jl; ++ j ) {
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var group = groups[ j ];
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var start = group.start;
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var count = group.count;
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for ( var i = start, il = start + count; i < il; i += 3 ) {
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handleVertex( indices[ i + 0 ] );
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handleVertex( indices[ i + 1 ] );
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handleVertex( indices[ i + 2 ] );
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}
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}
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}
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};
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