> ## Documentation Index
> Fetch the complete documentation index at: https://docs.opengeometry.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Cylinder

> Create cylindrical shapes with customizable dimensions and segments

## Overview

The `Cylinder` class creates 3D cylindrical shapes. Cylinders are created on the XZ plane and extruded along the Y-axis. They support partial angles for creating cylindrical sections and customizable segment counts for geometry resolution.

## Constructor

```typescript theme={null}
const cylinder = new Cylinder(options?: ICylinderOptions);
```

### ICylinderOptions

<ParamField path="ogid" type="string" optional>
  Unique identifier for the cylinder. Auto-generated if not provided.
</ParamField>

<ParamField path="center" type="Vector3" required>
  Center point of the cylinder in 3D space.

  ```typescript theme={null}
  center: new Vector3(0, 0, 0)
  ```
</ParamField>

<ParamField path="radius" type="number" required>
  Radius of the cylinder base.

  ```typescript theme={null}
  radius: 5  // Units in scene space
  ```
</ParamField>

<ParamField path="height" type="number" required>
  Height of the cylinder along the Y-axis.

  ```typescript theme={null}
  height: 10
  ```
</ParamField>

<ParamField path="segments" type="number" required>
  Number of segments around the cylinder circumference. Higher values create smoother cylinders.

  ```typescript theme={null}
  segments: 32  // Default value
  ```
</ParamField>

<ParamField path="angle" type="number" required>
  Sweep angle in radians. Use `2 * Math.PI` for a complete cylinder.

  ```typescript theme={null}
  angle: 2 * Math.PI      // Full cylinder
  angle: Math.PI          // Half cylinder
  angle: Math.PI / 2      // Quarter cylinder
  ```
</ParamField>

<ParamField path="color" type="number" required>
  Hexadecimal color value for the cylinder.

  ```typescript theme={null}
  color: 0x00ff00  // Green
  ```
</ParamField>

## Methods

### setConfig()

Updates the cylinder configuration and regenerates geometry.

```typescript theme={null}
cylinder.setConfig(options: ICylinderOptions): void
```

**Example:**

```typescript theme={null}
cylinder.setConfig({
  center: new Vector3(0, 5, 0),
  radius: 3,
  height: 12,
  segments: 48,
  angle: 2 * Math.PI,
  color: 0x3498db
});
```

### getBrep()

Returns the B-Rep (Boundary Representation) data as a parsed JSON object.

```typescript theme={null}
cylinder.getBrep(): object | null
```

**Example:**

```typescript theme={null}
const brepData = cylinder.getBrep();
if (brepData) {
  console.log('Vertices:', brepData.vertices.length);
  console.log('Faces:', brepData.faces.length);
}
```

### generateGeometry()

Regenerates the THREE.js geometry from the current configuration. Called automatically after setConfig().

```typescript theme={null}
cylinder.generateGeometry(): void
```

### discardGeometry()

Disposes of the current geometry to free memory.

```typescript theme={null}
cylinder.discardGeometry(): void
```

## Properties

<ResponseField name="ogid" type="string">
  Unique identifier for the cylinder instance.
</ResponseField>

<ResponseField name="options" type="ICylinderOptions">
  Current cylinder configuration.

  ```typescript theme={null}
  const currentRadius = cylinder.options.radius;
  const currentHeight = cylinder.options.height;
  ```
</ResponseField>

<ResponseField name="radius" type="number">
  Get or set the cylinder radius. Setting triggers geometry regeneration.

  ```typescript theme={null}
  cylinder.radius = 8;  // Update radius and regenerate
  ```
</ResponseField>

<ResponseField name="color" type="number">
  Get or set the cylinder color.

  ```typescript theme={null}
  cylinder.color = 0xff0000;  // Change to red
  ```
</ResponseField>

<ResponseField name="outline" type="boolean">
  Enable or disable outline rendering.

  ```typescript theme={null}
  cylinder.outline = true;   // Show edges
  cylinder.outline = false;  // Hide edges
  ```
</ResponseField>

## Usage Examples

### Basic Cylinder

```typescript theme={null}
import { Cylinder, Vector3 } from 'opengeometry';

const cylinder = new Cylinder({
  center: new Vector3(0, 0, 0),
  radius: 5,
  height: 10,
  segments: 32,
  angle: 2 * Math.PI,
  color: 0x2ecc71
});

// Add to scene
scene.add(cylinder);
```

### Half Cylinder (Partial Angle)

```typescript theme={null}
import { Cylinder, Vector3 } from 'opengeometry';

const halfCylinder = new Cylinder({
  center: new Vector3(0, 0, 0),
  radius: 4,
  height: 8,
  segments: 32,
  angle: Math.PI,  // 180 degrees
  color: 0xe74c3c
});

halfCylinder.outline = true;
```

### High-Resolution Cylinder

```typescript theme={null}
import { Cylinder, Vector3 } from 'opengeometry';

// Smooth cylinder with many segments
const smoothCylinder = new Cylinder({
  center: new Vector3(0, 0, 0),
  radius: 6,
  height: 12,
  segments: 64,  // High segment count for smoothness
  angle: 2 * Math.PI,
  color: 0x3498db
});
```

### Updating Cylinder Dynamically

```typescript theme={null}
import { Cylinder, Vector3 } from 'opengeometry';

const cylinder = new Cylinder({
  center: new Vector3(0, 0, 0),
  radius: 5,
  height: 10,
  segments: 32,
  angle: 2 * Math.PI,
  color: 0x9b59b6
});

// Animate radius change
function animate() {
  const time = Date.now() * 0.001;
  cylinder.radius = 5 + Math.sin(time) * 2;
  requestAnimationFrame(animate);
}
animate();
```

## Implementation Details

### Geometry Generation

Cylinders are generated by creating a circular base on the XZ plane and extruding it along the Y-axis. The base circle is centered at `center.y - height/2`, and the top is at `center.y + height/2`.

**Rust Implementation:** `/workspace/source/main/opengeometry/src/primitives/cylinder.rs:90-134`

```rust theme={null}
let half_height = self.height / 2.0;
let mut start_angle: f64 = 0.0;
let angle_step = self.angle / self.segments as f64;

for _ in 0..segment_count {
    let x = self.center.x + self.radius * start_angle.cos();
    let y = self.center.y - half_height;
    let z = self.center.z + self.radius * start_angle.sin();
    // ...
}
```

### Material Configuration

Cylinders use MeshStandardMaterial with transparency for better visual integration:

**Source:** `/workspace/source/main/opengeometry/src/shapes/cylinder.ts:98-102`

```typescript theme={null}
const material = new THREE.MeshStandardMaterial({
  color: this.options.color,
  transparent: true,
  opacity: 0.6,
});
```

### Partial Cylinders

When `angle < 2π`, an additional center vertex is added to the base circle to properly close the cylindrical section.

**Source:** `/workspace/source/main/opengeometry/src/primitives/cylinder.rs:108-115`

## Best Practices

<Tip>
  **Segment Count:** Use 32 segments for general purposes. Increase to 64+ for close-up views or precision modeling. Reduce to 16-24 for distant objects to improve performance.
</Tip>

<Warning>
  **Angle Range:** The angle parameter should be between 0 and `2 * Math.PI`. Values outside this range may produce unexpected results.
</Warning>

<Info>
  **Outline Performance:** Enabling outlines adds line geometry. For scenes with many cylinders, consider toggling outlines based on selection or zoom level.
</Info>

## Live Demo

<Card title="Cylinder Demo" icon="play" href="https://demos.opengeometry.io/shapes/cylinder.html">
  Try the Cylinder shape in the browser
</Card>

## See Also

<CardGroup cols={2}>
  <Card title="Sweep" icon="bezier-curve" href="/OpenGeometry/api/shapes/sweep">
    Custom profile extrusions
  </Card>

  <Card title="Sphere" icon="globe" href="/OpenGeometry/api/shapes/sphere">
    Spherical shapes
  </Card>

  <Card title="Cuboid" icon="cube" href="/OpenGeometry/api/shapes/cuboid">
    Rectangular boxes
  </Card>
</CardGroup>