Ellipse Entity (EllipseEnt)

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Ellipse Entity (EllipseEnt)

EllipseEnt represents an ellipse entity in CAD, defined by a center point, major axis, minor axis, and rotation angle.

Overview

An ellipse is a type of conic curve widely used in engineering design. EllipseEnt supports both full ellipses and elliptical arcs.

Constructor

import { EllipseEnt, Point2D } from 'vjcad';

// Shorthand notation (recommended)
const ellipse1 = new EllipseEnt([100, 100], 50, 30, 0);

// Point2D notation
const ellipse2 = new EllipseEnt(new Point2D(100, 100), 50, 30, 0);

ellipse1.setDefaults();

Shorthand Notation

Both the constructor and the center property support coordinates in [x, y] array form, avoiding the need to write new Point2D(...) every time.

Properties

Property	Type	Description
`center`	Point2D	Ellipse center point
`majorRadius`	number	Major axis radius
`minorRadius`	number	Minor axis radius
`majorAxis`	number	Major axis angle (radians)
`rotation`	number	Rotation angle (alias for `majorAxis`)
`startAngle`	number	Start angle (elliptical arc, radians)
`endAngle`	number	End angle (elliptical arc, radians)
`isEllipse`	boolean	Whether it is a full ellipse (read-only)

Examples

Full Ellipse

import { Engine, EllipseEnt } from 'vjcad';

// Create an ellipse (supports [x, y] array form)
const ellipse = new EllipseEnt([50, 50], 40, 20, 0);  // center, major radius, minor radius, rotation angle
ellipse.setDefaults();

Engine.addEntities(ellipse);

console.log('Center:', ellipse.center);
console.log('Major radius:', ellipse.majorRadius);
console.log('Minor radius:', ellipse.minorRadius);

Elliptical Arc

import { Engine, EllipseEnt } from 'vjcad';

// Create an elliptical arc (upper half)
const ellipseArc = new EllipseEnt([50, 80], 40, 20, 0);
ellipseArc.startAngle = 0;
ellipseArc.endAngle = Math.PI;  // 180 degrees
ellipseArc.setDefaults();

Engine.addEntities(ellipseArc);

// Rotated elliptical arc
const rotatedArc = new EllipseEnt([150, 80], 40, 20, Math.PI / 6); // rotated 30 degrees
rotatedArc.startAngle = Math.PI / 4;
rotatedArc.endAngle = Math.PI * 5 / 4;  // from 45 degrees to 225 degrees
rotatedArc.setDefaults();

Engine.addEntities(rotatedArc);