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/**
* @author zz85 / https://github.com/zz85
* @author Mugen87 / https://github.com/Mugen87
*
* Parametric Surfaces Geometry
* based on the brilliant article by @prideout http://prideout.net/blog/?p=44
*/
import { Geometry } from '../core/Geometry.js';
import { BufferGeometry } from '../core/BufferGeometry.js';
import { Float32BufferAttribute } from '../core/BufferAttribute.js';
import { Vector3 } from '../math/Vector3.js';
// ParametricGeometry
function ParametricGeometry( func, slices, stacks ) {
Geometry.call( this );
this.type = 'ParametricGeometry';
this.parameters = {
func: func,
slices: slices,
stacks: stacks
};
this.fromBufferGeometry( new ParametricBufferGeometry( func, slices, stacks ) );
this.mergeVertices();
}
ParametricGeometry.prototype = Object.create( Geometry.prototype );
ParametricGeometry.prototype.constructor = ParametricGeometry;
// ParametricBufferGeometry
function ParametricBufferGeometry( func, slices, stacks ) {
BufferGeometry.call( this );
this.type = 'ParametricBufferGeometry';
this.parameters = {
func: func,
slices: slices,
stacks: stacks
};
// buffers
var indices = [];
var vertices = [];
var normals = [];
var uvs = [];
var EPS = 0.00001;
var normal = new Vector3();
var p0 = new Vector3(), p1 = new Vector3();
var pu = new Vector3(), pv = new Vector3();
var i, j;
if ( func.length < 3 ) {
console.error( 'THREE.ParametricGeometry: Function must now modify a Vector3 as third parameter.' );
}
// generate vertices, normals and uvs
var sliceCount = slices + 1;
for ( i = 0; i <= stacks; i ++ ) {
var v = i / stacks;
for ( j = 0; j <= slices; j ++ ) {
var u = j / slices;
// vertex
func( u, v, p0 );
vertices.push( p0.x, p0.y, p0.z );
// normal
// approximate tangent vectors via finite differences
if ( u - EPS >= 0 ) {
func( u - EPS, v, p1 );
pu.subVectors( p0, p1 );
} else {
func( u + EPS, v, p1 );
pu.subVectors( p1, p0 );
}
if ( v - EPS >= 0 ) {
func( u, v - EPS, p1 );
pv.subVectors( p0, p1 );
} else {
func( u, v + EPS, p1 );
pv.subVectors( p1, p0 );
}
// cross product of tangent vectors returns surface normal
normal.crossVectors( pu, pv ).normalize();
normals.push( normal.x, normal.y, normal.z );
// uv
uvs.push( u, v );
}
}
// generate indices
for ( i = 0; i < stacks; i ++ ) {
for ( j = 0; j < slices; j ++ ) {
var a = i * sliceCount + j;
var b = i * sliceCount + j + 1;
var c = ( i + 1 ) * sliceCount + j + 1;
var d = ( i + 1 ) * sliceCount + j;
// faces one and two
indices.push( a, b, d );
indices.push( b, c, d );
}
}
// build geometry
this.setIndex( indices );
this.addAttribute( 'position', new Float32BufferAttribute( vertices, 3 ) );
this.addAttribute( 'normal', new Float32BufferAttribute( normals, 3 ) );
this.addAttribute( 'uv', new Float32BufferAttribute( uvs, 2 ) );
}
ParametricBufferGeometry.prototype = Object.create( BufferGeometry.prototype );
ParametricBufferGeometry.prototype.constructor = ParametricBufferGeometry;
export { ParametricGeometry, ParametricBufferGeometry };
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