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Overview

The ArcPrimitive class creates a circular arc segment defined by a center point, radius, and start/end angles. It extends the kernel Arc class and implements the IPrimitive interface for selection and editing capabilities.

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Constructor

new ArcPrimitive(arcConfig?: ArcOptions)
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arcConfig
ArcOptions
Configuration object for the arc primitive

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ArcOptions

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ogid
string
Unique identifier for the arc object. Auto-generated if not provided.
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center
Array<number>
required
Center point coordinates as [x, y, z]
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radius
number
required
Radius of the arc
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startAngle
number
required
Starting angle in radians
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endAngle
number
required
Ending angle in radians
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segments
number
required
Number of segments to approximate the arc curve. Higher values create smoother arcs.
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color
number
required
Arc color as hexadecimal number (e.g., 0xFF0000 for red)

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Properties

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arcCenter
Vector3
Sets the center point of the arc. Updates geometry automatically.
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arcRadius
number
Gets or sets the arc radius. Updates geometry automatically.
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arcStartAngle
number
Gets or sets the starting angle in radians. Updates geometry automatically.
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arcEndAngle
number
Gets or sets the ending angle in radians. Updates geometry automatically.
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arcSegments
number
Gets or sets the number of segments. Updates geometry automatically.
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arcColor
number
Gets or sets the arc color. Updates appearance automatically.
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selected
boolean
Indicates whether the arc is currently selected
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edit
boolean
Indicates whether the arc is in edit mode
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ogType
string
Returns 'ArcPrimitive' - the type identifier

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Methods

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getOPConfig()

Returns the current configuration of the arc. 
getOPConfig(): ArcOptions
Returns: ArcOptions - Current arc configuration

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setOPGeometry()

Updates the arc geometry based on current property values. Called automatically when properties change. 
setOPGeometry(): void

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Examples

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Create a Semicircle

import { ArcPrimitive } from 'openplans';

const semicircle = new ArcPrimitive({
  center: [0, 0, 0],
  radius: 5,
  startAngle: 0,
  endAngle: Math.PI, // 180 degrees
  segments: 16,
  color: 0x000000
});

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Create a Full Circle

const circle = new ArcPrimitive({
  center: [10, 0, 0],
  radius: 3,
  startAngle: 0,
  endAngle: Math.PI * 2, // 360 degrees
  segments: 32,
  color: 0x0000FF // Blue
});

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Create a Quarter Arc

const quarterArc = new ArcPrimitive({
  center: [0, 0, 0],
  radius: 10,
  startAngle: 0,
  endAngle: Math.PI / 2, // 90 degrees
  segments: 16,
  color: 0xFF0000 // Red
});

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Update Arc Properties

// Increase radius
quarterArc.arcRadius = 15;

// Make it smoother
quarterArc.arcSegments = 32;

// Change color to green
quarterArc.arcColor = 0x00FF00;

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Get Arc Configuration

const config = semicircle.getOPConfig();
console.log(config);
// Output:
// {
//   ogid: 'auto-generated-id',
//   center: [0, 0, 0],
//   radius: 5,
//   startAngle: 0,
//   endAngle: 3.14159...,
//   segments: 16,
//   color: 0x000000
// }
Last modified on March 7, 2026