aframe
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A web framework for building virtual reality experiences.
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Markdown
---
title: geometry
type: components
layout: docs
parent_section: docs
section_title: Components
section_order: 4
source_code: src/components/geometry.js
examples:
- title: Creating Shapes
src: https://glitch.com/edit/#!/ex-2-geometry?path=index.html:1:0
- title: Texture on Shapes
src: https://glitch.com/edit/#!/ex-2a-texture-on-shape?path=index.html:1:0
- title: Shape as Entity
src: https://glitch.com/edit/#!/ex-2b-shape-as-entity?path=index.html:1:0
- title: Animating Shapes
src: https://glitch.com/edit/#!/ex-2c-animating-shapes?path=index.html:1:0
- title: Animating Shapes with Components
src: https://glitch.com/edit/#!/ex-2d-animating-shapes-with-components?path=index.html:1:0
---
The geometry component provides a basic shape for an entity. The `primitive`
property defines the general shape. Geometric primitives, in computer graphics,
are irreducible basic shapes. A material component is commonly defined to
provide an appearance alongside the shape to create a complete mesh.
Overview of available geometries:
<!--toc-->
## Base Properties
Every geometry type will have these properties:
| Property | Description | Default Value |
|-----------|--------------------------------------------------------------------------------------------------------------------------------------|---------------|
| primitive | Name of a geometry (e.g., one of the geometries listed below). Determines the geometry type and what other properties are available. | box |
| skipCache | Disable retrieving the shared geometry object from the cache. | false |
## Built-in Geometries
### `box`
The box geometry defines boxes (i.e., any quadrilateral, not just cubes).
```html
<a-entity geometry="primitive: box; width: 1; height: 1; depth: 1"></a-entity>
```
| Property | Description | Default Value |
|----------------|------------------------------------------------|---------------|
| width | Width (in meters) of the sides on the X axis. | 1 |
| height | Height (in meters) of the sides on the Y axis. | 1 |
| depth | Depth (in meters) of the sides on the Z axis. | 1 |
| segmentsDepth | Number of segmented faces on the z-axis | 1 |
| segmentsHeight | Number of segmented faces on the y-axis | 1 |
| segmentsWidth | Number of segmented faces on the x-axis | 1 |
### `circle`
The circle geometry creates flat two-dimensional circles. These can be complete
circles or partial circles (like Pac-Man). Note that because circles are flat,
A-Frame will only render a single face of the circle if we don't specify `side:
double` on the `material` component.
```html
<a-entity geometry="primitive: circle; radius: 1" material="side: double"></a-entity>
```
| Property | Description | Default Value |
|-------------|----------------------------------------------------------------------------------------------------------------------------------|---------------|
| radius | Radius (in meters) of the circle. | 1 |
| segments | Number of triangles to construct the circle, like pizza slices. A higher number of segments means the circle will be more round. | 32 |
| thetaStart | Start angle for first segment. Can be used to define a partial circle. | 0 |
| thetaLength | The central angle (in degrees). Defaults to `360`, which makes for a complete circle. | 360 |
#### `thetaLength` and `thetaStart` Properties
In degrees, `thetaStart` defines where to start a circle or arc and
`thetaLength` defines where a circle or arc ends. If we wanted to make a `(`
shape, we would start the circle halfway through and define the length as half
of a circle. We can do this with `thetaStart: 180; thetaLength: 180`. Or if we
wanted to make a `)` shape, we can do `thetaStart: 0; thetaLength: 180`.
Useful cases might be to animating `thetaStart` to create a spinner effect or
animating `thetaLength` on a fuse-based cursor for visual feedback.
### `cone`
The cone geometry is a cylinder geometry that have different top and bottom radii.
```html
<a-entity geometry="primitive: cone; radiusBottom: 1; radiusTop: 0.1"></a-entity>
```
| Property | Description | Default Value |
|----------------|-----------------------------------------------------------------|---------------|
| height | Height of the cone. | 2 |
| openEnded | Whether the ends of the cone are open (true) or capped (false). | false |
| radiusBottom | Radius of the bottom end of the cone. | 1 |
| radiusTop | Radius of the top end of the cone. | 1 |
| segmentsRadial | Number of segmented faces around the circumference of the cone. | 36 |
| segmentsHeight | Number of rows of faces along the height of the cone. | 18 |
| thetaStart | Starting angle in degrees. | 0 |
| thetaLength | Central angle in degrees. | 360 |
### `cylinder`
The cylinder geometry creates cylinders in the traditional sense like a
Coca-Cola™ can, but it can also define shapes such as tubes and curved
surfaces.
We can create a basic cylinder using height and radius:
```html
<a-entity geometry="primitive: cylinder; height: 3; radius: 2"></a-entity>
```
We can create a tube by making the cylinder open-ended, which removes the top
and bottom surfaces of the cylinder such that the inside is visible. Then we
need a double-sided material to render properly:
```html
<!-- Tube -->
<a-entity geometry="primitive: cylinder; openEnded: true" material="side: double"></a-entity>
```
We can create a curved surfaces by specifying the arc via `thetaLength` such
that the cylinder doesn't curve all the way around, making the cylinder
open-ended, and then making the material double-sided:
```html
<!-- Curved surface -->
<a-entity geometry="primitive: cylinder; openEnded: true; thetaLength: 180"
material="side: double"></a-entity>
```
| Property | Description | Default Value |
|----------------|---------------------------------------------------------------------|---------------|
| radius | Radius of the cylinder. | 1 |
| height | Height of the cylinder. | 2 |
| segmentsRadial | Number of segmented faces around the circumference of the cylinder. | 36 |
| segmentsHeight | Number of rows of faces along the height of the cylinder. | 18 |
| openEnded | Whether the ends of the cylinder are open (true) or capped (false). | false |
| thetaStart | Starting angle in degrees. | 0 |
| thetaLength | Central angle in degrees. | 360 |
We can create [prisms][prisms-wiki] by changing the number of radial segments
(i.e., sides). For example, to make a hexagonal prism:
```html
<!-- Hexagonal prism -->
<a-entity geometry="primitive: cylinder; segmentsRadial: 6"></a-entity>
```
### `dodecahedron`
The dodecahedron geometry creates a polygon with twelve equally-sized faces.
```html
<a-entity geometry="primitive: dodecahedron; radius: 2"></a-entity>
```
| Property | Description | Default Value |
|----------|-----------------------------------------|---------------|
| radius | Radius (in meters) of the dodecahedron. | 1 |
### `octahedron`
The octahedron geometry creates a polygon with eight equilateral triangular faces.
```html
<a-entity geometry="primitive: octahedron"></a-entity>
```
| Property | Description | Default Value |
|----------|----------------------------------------|---------------|
| radius | Radius (in meters) of the octahedron. | 1 |
### `icosahedron`
The icosahedron geometry creates a polygon with twenty equilateral triangular faces.
```html
<a-entity geometry="primitive: icosahedron"></a-entity>
```
| Property | Description | Default Value |
|----------|----------------------------------------|---------------|
| radius | Radius (in meters) of the icosahedron. | 1 |
### `plane`
The plane geometry creates a flat surface. Because planes are flat, A-Frame
will render only a single face of the plane unless we specify `side: double` on
the `material` component.
```html
<a-entity geometry="primitive: plane; height: 10; width: 10" material="side: double"></a-entity>
```
| Property | Description | Default Value |
|----------------|-----------------------------------------|---------------|
| width | Width along the X axis. | 1 |
| height | Height along the Y axis. | 1 |
| segmentsHeight | Number of segmented faces on the y-axis | 1 |
| segmentsWidth | Number of segmented faces on the x-axis | 1 |
### `ring`
The ring geometry creates a flat ring, like a [CD][cd]. Because the ring is
flat, A-Frame will only render a single face of the ring unless we specify `side:
double` the `material` component.
```html
<a-entity geometry="primitive: ring; radiusInner: 0.5; radiusOuter: 1"
material="side: double"></a-entity>
```
| Property | Description | Default Value |
|---------------|------------------------------------------------------------------------|---------------|
| radiusInner | Radius of the inner hole of the ring. | 1 |
| radiusOuter | Radius of the outer edge of the ring. | 1 |
| segmentsTheta | Number of segments. A higher number means the ring will be more round. | 32 |
| segmentsPhi | Number of triangles within each face defined by segmentsTheta. | 8 |
| thetaStart | Starting angle in degrees. | 0 |
| thetaLength | Central angle in degrees. | 360 |
### `sphere`
The sphere geometry creates spheres (e.g., balls). We can create a basic sphere:
```html
<a-entity geometry="primitive: sphere; radius: 2"></a-entity>
```
We can create polyhedrons and abstract shapes by specifying the number of
horizontal angles and faces:
```html
<a-entity geometry="primitive: sphere; segmentsWidth: 2; segmentsHeight: 8"></a-entity>
```
| Property | Description | Default Value |
|----------------|--------------------------------|---------------|
| radius | Radius of the sphere. | 1 |
| segmentsWidth | Number of horizontal segments. | 18 |
| segmentsHeight | Number of vertical segments. | 36 |
| phiStart | Horizontal starting angle. | 0 |
| phiLength | Horizontal sweep angle size. | 360 |
| thetaStart | Vertical starting angle. | 0 |
| thetaLength | Vertical sweep angle size. | 360 |
### `tetrahedron`
The tetrahedron geometry creates a polygon with four triangular faces.
```html
<a-entity geometry="primitive: tetrahedron; radius: 2"></a-entity>
```
| Property | Description | Default Value |
|----------|------------------------------------------------------------------------------|---------------|
| radius | Radius (in meters) of the tetrahedron. | 1 |
### `torus`
The torus geometry creates a donut or curved tube shape:
```html
<!-- Half donut -->
<a-entity geometry="primitive: torus; radius: 2; radiusTubular: 0.5; arc: 180"></a-entity>
```
| Property | Description | Default Value |
|-----------------|-----------------------------------------------------------------------------------------------------------------|---------------|
| radius | Radius of the outer edge of the torus. | 1 |
| radiusTubular | Radius of the tube. | 0.2 |
| segmentsRadial | Number of segments along the circumference of the tube ends. A higher number means the tube will be more round. | 36 |
| segmentsTubular | Number of segments along the circumference of the tube face. A higher number means the tube will be more round. | 32 |
| arc | Central angle. | 360 |
### `torusKnot`
The torus knot geometry creates a pretzel shape. A pair of coprime integers,
`p` and `q`, defines the particular shape of the pretzel. If `p` and `q` are
not coprime the result will be a torus link:
```html
<a-entity geometry="primitive: torusKnot; p: 3; q:7"></a-entity>
```
| Property | Description | Default Value |
|-----------------|-----------------------------------------------------------------------------------------------------------------|---------------|
| radius | Radius that contains the torus knot. | 1 |
| radiusTubular | Radius of the tubes of the torus knot. | 0.2 |
| segmentsRadial | Number of segments along the circumference of the tube ends. A higher number means the tube will be more round. | 36 |
| segmentsTubular | Number of segments along the circumference of the tube face. A higher number means the tube will be more round. | 32 |
| p | How many times the geometry winds around its axis of rotational symmetry. | 2 |
| q | How many times the geometry winds around a circle in the interior of the torus. | 3 |
### `triangle`
The triangle geometry creates a flat two-dimensional triangle. Because triangles are flat,
A-Frame will render only a single face, which is the one with `vertexA`, `vertexB`, and
`vertexC` appear in counterclockwise order on the screen, unless we specify `side: double` on
the `material` component.
```html
<a-entity geometry="primitive: triangle" material="side: double"></a-entity>
```
| Property | Description | Default Value |
|----------|--------------------------------------------|---------------|
| vertexA | Coordinates of one of the three vertices | 0 0.5 0 |
| vertexB | Coordinates of one of the three vertices | -0.5 -0.5 0 |
| vertexC | Coordinates of one of the three vertices | 0.5 -0.5 0 |
## Register a Custom Geometry
We can register our own geometries using `AFRAME.registerGeometry` and creating
an object that is an instance of [`THREE.BufferGeometry`][three-geometry].
Recent versions of three.js rename generators such as PlaneBufferGeometry to just
[PlaneGeometry](https://threejs.org/docs/#api/en/geometries/PlaneGeometry),
but support the old name as an alias. See the three.js manual to learn about creating a
[custom `BufferGeometry`](https://threejs.org/manual/#en/custom-buffergeometry).
A-Frame
registers all built-in geometries using this API. Here is how A-Frame registers
the `box` geometry:
```js
AFRAME.registerGeometry('box', {
schema: {
depth: {default: 1, min: 0},
height: {default: 1, min: 0},
width: {default: 1, min: 0},
segmentsHeight: {default: 1, min: 1, max: 20, type: 'int'},
segmentsWidth: {default: 1, min: 1, max: 20, type: 'int'},
segmentsDepth: {default: 1, min: 1, max: 20, type: 'int'}
},
init: function (data) {
this.geometry = new THREE.BoxGeometry(data.width, data.height, data.depth);
}
});
```
Like with registering components, we provide a name, a
[schema][component-schema] that will expose the properties of the geometry, and
lifecycle methods. Then we need to create the geometry and set on
`this.geometry` through the `init` lifecycle method.
When a geometry component sets its `primitive` property to the custom geometry
name, we can set the properties of the custom geometry on the geometry
component. Say we registered a custom geometry:
```js
AFRAME.registerGeometry('example', {
schema: {
vertices: {
default: ['-10 10 0', '-10 -10 0', '10 -10 0'],
}
},
init: function (data) {
var geometry = new THREE.BufferGeometry();
const pointsArray = new Array();
data.vertices.map(function (vertex) {
var points = vertex.split(' ').map(function(x){return parseInt(x);});
pointsArray.push(new THREE.Vector3(points[0], points[1], points[2]));
});
geometry.setFromPoints(pointsArray);
geometry.computeBoundingBox();
geometry.computeVertexNormals();
this.geometry = geometry;
}
});
```
We can then use that custom geometry in HTML:
```html
<a-entity geometry="primitive: example; vertices: 1 1 -3, 3 1 -3, 2 2 -3"></a-entity>
```
[cd]: https://en.wikipedia.org/wiki/Compact_disc
[component-schema]: ../core/component.md#schema
[prisms-wiki]: https://en.wikipedia.org/wiki/Prism_%28geometry%29
[three-geometry]: https://threejs.org/docs/#api/en/core/BufferGeometry