Basic Entities

This chapter introduces the basic geometry entities in WebCAD.

LineEnt Line

import { LineEnt, Point2D } from 'vjcad';

const line = new LineEnt(
  new Point2D(0, 0),    // Start point
  new Point2D(100, 100) // End point
);
line.setDefaults();

// Property access
console.log('Start point:', line.startPoint);
console.log('End point:', line.endPoint);
console.log('Mid point:', line.midPoint);
console.log('Length:', line.Length);
console.log('Angle:', line.angle);  // Radians

// Geometric transformations (supports shorthand syntax)
line.move([0, 0], [50, 50]);       // Move
line.rotate([0, 0], Math.PI / 4);  // Rotate 45 degrees
line.scale([0, 0], 2);             // Scale up 2x
line.mirror([0, 0], [1, 0]);       // Horizontal mirror

// Bounding box
const bbox = line.boundingBox();
console.log('Bounds:', bbox.pt1, bbox.pt2);

LineEnt Properties

Property	Type	Description
startPoint	Point2D	Start point
endPoint	Point2D	End point
midPoint	Point2D	Mid point (read-only)
Length	number	Length (read-only)
angle	number	Angle (radians, read-only)

CircleEnt Circle

import { CircleEnt, Point2D } from 'vjcad';

const circle = new CircleEnt(
  new Point2D(50, 50),  // Center
  30                     // Radius
);
circle.setDefaults();

// Modify properties
circle.center = new Point2D(100, 100);
circle.radius = 50;

CircleEnt Properties

Property	Type	Description
center	Point2D	Center
radius	number	Radius

ArcEnt Arc

import { ArcEnt, Point2D } from 'vjcad';

const arc = new ArcEnt();
arc.center = new Point2D(50, 50);
arc.radius = 30;
arc.startAngle = 0;              // Start angle (radians)
arc.endAngle = Math.PI / 2;      // End angle (radians)
arc.setDefaults();

ArcEnt Properties

Property	Type	Description
center	Point2D	Center
radius	number	Radius
startAngle	number	Start angle (radians)
endAngle	number	End angle (radians)

PolylineEnt Polyline

import { PolylineEnt, BulgePoint, BulgePoints, Point2D } from 'vjcad';

const pline = new PolylineEnt();
pline.setDefaults();

// Add vertices (BulgePoint constructor: new BulgePoint(Point2D, bulge))
pline.bulgePoints.add(new BulgePoint(new Point2D(0, 0), 0));      // Straight segment
pline.bulgePoints.add(new BulgePoint(new Point2D(100, 0), 0.5));  // Arc segment with bulge
pline.bulgePoints.add(new BulgePoint(new Point2D(100, 100), 0));
pline.bulgePoints.add(new BulgePoint(new Point2D(0, 100), 0));
pline.isClosed = true;  // Closed polyline

// Set global width
pline.globalWidth = 5;

PolylineEnt Properties

Property	Type	Description
bulgePoints	BulgePoints	Vertex collection
isClosed	boolean	Whether closed
globalWidth	number	Global width

BulgePoint Description

BulgePoint constructor: new BulgePoint(pointCoordinate: Point2D, bulgeValue: number)

• point2d: Vertex coordinate (Point2D type)
• bulge: Bulge value
  • bulge = 0: Straight line segment
  • bulge > 0: Counter-clockwise arc
  • bulge < 0: Clockwise arc
  • bulge = 1: Semicircle

EllipseEnt Ellipse

import { EllipseEnt, Point2D } from 'vjcad';

const ellipse = new EllipseEnt();
ellipse.center = new Point2D(50, 50);
ellipse.majorRadius = 40;
ellipse.minorRadius = 20;
ellipse.rotation = 0;
ellipse.setDefaults();

HatchEnt Hatch

import { HatchEnt, PolylineEnt, BulgePoints, BulgePoint, Point2D } from 'vjcad';

// Create boundary
const boundary = new PolylineEnt();
boundary.bulgePoints.add(new BulgePoint(new Point2D(0, 0), 0));
boundary.bulgePoints.add(new BulgePoint(new Point2D(100, 0), 0));
boundary.bulgePoints.add(new BulgePoint(new Point2D(100, 100), 0));
boundary.bulgePoints.add(new BulgePoint(new Point2D(0, 100), 0));
boundary.isClosed = true;

// Create hatch
const hatch = new HatchEnt();
hatch.setDefaults();
hatch.patternName = 'ANSI31';  // Pattern name
hatch.patternScale = 1;
hatch.patternAngle = 0;
hatch.addBoundary([boundary]);

Common Hatch Patterns

Pattern Name	Description
SOLID	Solid fill
ANSI31	45-degree diagonal lines
ANSI32	Cross lines
ANSI33	45-degree cross
ANSI34	Horizontal lines
ANSI35	Vertical lines

DotEnt Dot

import { DotEnt, Point2D } from 'vjcad';

const dot = new DotEnt(new Point2D(50, 50));
dot.setDefaults();

Next Steps

• Text Entities - Text, MText
• Blocks and Inserts - Block, Insert
• Custom Entities - Creating custom entities