three.fbo-helper
Version:
FrameBuffer Object inspector for three.js
92 lines (54 loc) • 1.84 kB
JavaScript
import { Curve } from '../core/Curve';
import { Vector2 } from '../../math/Vector2';
/**************************************************************
* Ellipse curve
**************************************************************/
function EllipseCurve( aX, aY, xRadius, yRadius, aStartAngle, aEndAngle, aClockwise, aRotation ) {
this.aX = aX;
this.aY = aY;
this.xRadius = xRadius;
this.yRadius = yRadius;
this.aStartAngle = aStartAngle;
this.aEndAngle = aEndAngle;
this.aClockwise = aClockwise;
this.aRotation = aRotation || 0;
}
EllipseCurve.prototype = Object.create( Curve.prototype );
EllipseCurve.prototype.constructor = EllipseCurve;
EllipseCurve.prototype.isEllipseCurve = true;
EllipseCurve.prototype.getPoint = function( t ) {
var twoPi = Math.PI * 2;
var deltaAngle = this.aEndAngle - this.aStartAngle;
var samePoints = Math.abs( deltaAngle ) < Number.EPSILON;
// ensures that deltaAngle is 0 .. 2 PI
while ( deltaAngle < 0 ) deltaAngle += twoPi;
while ( deltaAngle > twoPi ) deltaAngle -= twoPi;
if ( deltaAngle < Number.EPSILON ) {
if ( samePoints ) {
deltaAngle = 0;
} else {
deltaAngle = twoPi;
}
}
if ( this.aClockwise === true && ! samePoints ) {
if ( deltaAngle === twoPi ) {
deltaAngle = - twoPi;
} else {
deltaAngle = deltaAngle - twoPi;
}
}
var angle = this.aStartAngle + t * deltaAngle;
var x = this.aX + this.xRadius * Math.cos( angle );
var y = this.aY + this.yRadius * Math.sin( angle );
if ( this.aRotation !== 0 ) {
var cos = Math.cos( this.aRotation );
var sin = Math.sin( this.aRotation );
var tx = x - this.aX;
var ty = y - this.aY;
// Rotate the point about the center of the ellipse.
x = tx * cos - ty * sin + this.aX;
y = tx * sin + ty * cos + this.aY;
}
return new Vector2( x, y );
};
export { EllipseCurve };