dmnsgn / geom-sweep

Extrudes a shape along a path

geom-sweep

Extrudes a shape along a path.

Installation

npm install geom-sweep

Usage

import sweep from "geom-sweep";

// Create a circle
const path = [];
for (let i = 0; i < 50; i++) {
  path.push([
    Math.cos((i / 50) * 2 * Math.PI),
    Math.sin((i / 50) * 2 * Math.PI),
    0,
  ]);
}
// Create a square
const shape = [
  [1, 1, 0],
  [-1, 1, 0],
  [-1, -1, 0],
  [1, -1, 0],
];

const geometry = sweep({ positions: path }, shape, {
  radius: 0.5,
  closed: true,
  initialNormal: [0, 0, 1],
  withFrames: true,
});
// => {
//   positions: Float32Array(756),
//   normals: Float32Array(756),
//   uvs: Float32Array(504),
//   cells: Uint32Array(1512),
//   tangents?: Float32Array(756),
//   binormals?: Float32Array(756),
// }

API

sweep(geometry, shape, options, out?): geometry

Parameters

• geometry: { positions: TypedArray | Array<[x, y, z]>, normals?: TypedArray | Array<[x, y, z]>, tangents?: TypedArray | Array<[x, y, z]>, binormals?: TypedArray | Array<[x, y, z]> } – a geometry object with positions defining the path to extrude along.

• shape: Array<[x, y, z]> – positions defining the swept shape.

• options.radius: number (default: 1) - extruded geometry radius.

• options.closed: boolean (default: false) - is the path closed.

• options.closedShape: boolean (default: true) - is the shape path closed.

• options.caps: boolean (default: false) - add caps at the end.

• options.initialNormal: Array (default: null) - provide a starting normal for the frames. Default to the direction of the minimum tangent component.

• options.withFrames: boolean (default: false) - compute tangents and binormals.

• out: { positions: TypedArray, normals?: TypedArray, tangents?: TypedArray, binormals?: TypedArray } (default: {}) – a geometry object with pre-allocated typed array with each attributes being a multiple of shape length * path vertices count + (caps ? 2 : 0).

Returns

geometry: { positions: TypedArray, normals: TypedArray, uvs: TypedArray, cells: TypedArray, tangents?: TypedArray, binormals: TypedArray } - the extruded geometry with optional tangents and binormals.

License

MIT. See license file.