fireball/lib/geometries/CircleGeometry.js

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2018-12-25 13:59:22 +00:00
/**
* @author benaadams / https://twitter.com/ben_a_adams
* @author Mugen87 / https://github.com/Mugen87
* @author hughes
*/
import { Geometry } from '../core/Geometry.js';
import { BufferGeometry } from '../core/BufferGeometry.js';
import { Float32BufferAttribute } from '../core/BufferAttribute.js';
import { Vector3 } from '../math/Vector3.js';
import { Vector2 } from '../math/Vector2.js';
// CircleGeometry
function CircleGeometry( radius, segments, thetaStart, thetaLength ) {
Geometry.call( this );
this.type = 'CircleGeometry';
this.parameters = {
radius: radius,
segments: segments,
thetaStart: thetaStart,
thetaLength: thetaLength
};
this.fromBufferGeometry( new CircleBufferGeometry( radius, segments, thetaStart, thetaLength ) );
this.mergeVertices();
}
CircleGeometry.prototype = Object.create( Geometry.prototype );
CircleGeometry.prototype.constructor = CircleGeometry;
// CircleBufferGeometry
function CircleBufferGeometry( radius, segments, thetaStart, thetaLength ) {
BufferGeometry.call( this );
this.type = 'CircleBufferGeometry';
this.parameters = {
radius: radius,
segments: segments,
thetaStart: thetaStart,
thetaLength: thetaLength
};
radius = radius || 1;
segments = segments !== undefined ? Math.max( 3, segments ) : 8;
thetaStart = thetaStart !== undefined ? thetaStart : 0;
thetaLength = thetaLength !== undefined ? thetaLength : Math.PI * 2;
// buffers
var indices = [];
var vertices = [];
var normals = [];
var uvs = [];
// helper variables
var i, s;
var vertex = new Vector3();
var uv = new Vector2();
// center point
vertices.push( 0, 0, 0 );
normals.push( 0, 0, 1 );
uvs.push( 0.5, 0.5 );
for ( s = 0, i = 3; s <= segments; s ++, i += 3 ) {
var segment = thetaStart + s / segments * thetaLength;
// vertex
vertex.x = radius * Math.cos( segment );
vertex.y = radius * Math.sin( segment );
vertices.push( vertex.x, vertex.y, vertex.z );
// normal
normals.push( 0, 0, 1 );
// uvs
uv.x = ( vertices[ i ] / radius + 1 ) / 2;
uv.y = ( vertices[ i + 1 ] / radius + 1 ) / 2;
uvs.push( uv.x, uv.y );
}
// indices
for ( i = 1; i <= segments; i ++ ) {
indices.push( i, i + 1, 0 );
}
// 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 ) );
}
CircleBufferGeometry.prototype = Object.create( BufferGeometry.prototype );
CircleBufferGeometry.prototype.constructor = CircleBufferGeometry;
export { CircleGeometry, CircleBufferGeometry };