Geometry Extrude

A small and fast JavaScript library for extruding 2D polygons and polylines to 3D meshes. It depends on earcut to do triangulation.

Features

+ Extrude polygons with holes.

+ Extrude polylines with specific line thickness.

+ Generate position / uv / normal / indices TypedArray.

+ Support bevel style.

Basic Usage

Install with npm

``
npm i geometry-extrude
`

Extrude a simple square with hole

`js
import {extrudePolygon} from 'geometry-extrude';
const squareWithHole = [
[[0, 0], [10, 0], [10, 10], [0, 10]],
// Hole
[[2, 2], [8, 2], [8, 8], [2, 8]]
];
const {indices, position, uv, normal} = extrudePolygon([squareWithHole], {
depth: 2
});
`

$3

`js
const {indices, position, uv, normal} = extrudePolygon(squareWithHole);
const geometry = new clay.Geometry();
geometry.attributes.position.value = position;
geometry.attributes.texcoord0.value = uv;
geometry.attributes.normal.value = normal;
geometry.indices = indices;
`

$3

`js
const {indices, position, uv, normal} = extrudePolygon(squareWithHole);
const geometry = new THREE.BufferGeometry();
geometry.addAttribute('position', new THREE.Float32BufferAttribute(position, 3));
geometry.addAttribute('normal', new THREE.Float32BufferAttribute(normal, 3));
geometry.setIndex(new THREE.Uint16BufferAttribute(indices, 1));
`

Example

$3

`js
const {indices, position, uv, normal} = extrudePolygon(squareWithHole);
const draw = regl({
frag: ...,
vert: ...,

attributes: {
position: position,
uv: uv,
normal: norma
},

elements: indices
});
`

Example

Full API List

$3

`js
extrudePolygon(
// polygons same with coordinates of MultiPolygon type geometry in GeoJSON
// See http://wiki.geojson.org/GeoJSON_draft_version_6#MultiPolygon
polygons: GeoJSONMultiPolygonGeometry,
// Options of extrude
opts: {
// Can be a constant value, or a function.
// Default to be 1.
depth?: ((idx: number) => number) | number,
// Size of bevel, default to be 0, which is no bevel.
bevelSize?: number,
// Segments of bevel, default to be 2. Larger value will lead to smoother bevel.
bevelSegments?: number,
// Polygon or polyline simplification tolerance. Default to be 0.
// Use https://www.npmjs.com/package/simplify-js to do the simplification. Same with the tolerance parameter in it. The unit is same with depth and bevelSize
simplify?: number,
// If has smooth side, default to be false.
smoothSide?: boolean,
// If has smooth bevel, default to be false.
smoothBevel?: boolean,
// If exclude bottom faces, default to be false.
// Usefull when bottom side can't be seen.
excludeBottom?: boolean,
// Transform the polygon to fit this rect.
// Will keep polygon aspect if only width or height is given.
fitRect?: {x?: number, y?: number, width?: number: height?: number},
// Translate the polygon. Default to be [0, 0]
// Will be ignored if fitRect is given.
translate?: ArrayLike,
// Scale the polygon. Default to be [1, 1]
// Will be ignored if fitRect is given.
scale?: ArrayLike
}
) => {
indices: Uint16Array|Uint32Array,
position: Float32Array,
normal: Float32Array,
uv: Float32Array,
boundingRect: {x: number, y: number, width: number, height: number}
}
`

$3

`typescript
extrudePolyline(
// polylines same with coordinates of MultiLineString type geometry in GeoJSON
// See http://wiki.geojson.org/GeoJSON_draft_version_6#MultiLineString
polylines: GeoJSONMultiLineStringGeometry,
// Options of extrude
opts: {
////// Extended from opts in extrudePolygon

// Thickness of line, default to be 1
lineWidth?: number,
// default to be 2
miterLimit?: number
}
) => {
indices: Uint16Array|Uint32Array,
position: Float32Array,
normal: Float32Array,
uv: Float32Array,
boundingRect: {x: number, y: number, width: number, height: number}
}
`

$3

`typescript
extrudeGeoJSON(
// Extrude geojson with Polygon/LineString/MultiPolygon/MultiLineString geometries.
geojson: GeoJSON,
// Options of extrude
opts: {
////// Extended from opts in extrudePolygon

// Can be a constant value, or a function with parameter of each feature in geojson.
// Default to be 1.
depth?: ((feature: GeoJSONFeature) => number) | number
// Thickness of line, default to be 1
lineWidth?: number,
// default to be 2
miterLimit?: number
}
) => {
// Same result with extrudePolygon
polygon: Object,
// Same result with extrudePolyline
polyline: Object
}
``