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Table of Contents
Chevron DownGetting Started
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Geometry

The Geometry class holds a collection of vertex array attributes representing a geometric primitive.

A geometry is considered a "primitive" when it can be rendered with a single GPU draw call. Multiple geometry primitives can be composed into a composite geometry using the Mesh and Model classes.

To learn more about attributes refer to the Accessor class that holds metadata for each attributes.

Usage

Create a pyramid geometry (used in lesson 4 of learning WebGL examples).

const pyramidGeometry= new Geometry({
  attributes: {
    positions: new Float32Array([ ... ]),
    colors: {
      size: 4,
      value: new Float32Array([ ... ])
    }
  }
});

Properties

id - (string, optional)

An id for the model. If not provided, a random unique identifier will be created.

drawMode : Number

The draw mode, or primitive type.

Some options are GL.TRIANGLES (default), GL.TRIANGLE_STRIP, GL.POINTS, GL.LINES.

attributes - (object, optional)

An object with buffer/attribute names and buffer/attribute descriptors to be set before rendering the model.

attributes : Object

A map of Accessor instances describing the geometry of this primitive.

indices : Accessor

An optional Accessor instance that contains the indices (aka elements) for this geometry. Can be null or undefined if this primitive doesn't use indices. Note that indices can also be stored inside attributes.

material : Object

An object with key/value pairs that indicate how various uniforms should be set up before the GPU draw call. The Geometry class itself does not directly use the contents of the material field, however other classes such as Mesh will refer to it if available, and normally expects it to be set to an instance of the Material class.

Methods

constructor(props : Object)

The constructor for the Geometry class. Use this to create a new Geometry.

const geometry = new Geometry(props);

setProps(props : Object)

Update properties

Types and Enumerations

drawMode

Follows glTF/OpenGL/WebGL conventions:

ValuePrimitive Mode
0POINTS
1LINES
2LINE_LOOP
3LINE_STRIP
4TRIANGLES
5TRIANGLE_STRIP
6TRIANGLE_FAN

Typical Attributes

AttributeDescription
indices(array, optional) An array of numbers describing the vertex indices for each face.
positions(array, optional) An array of floats that describe the vertices of the model.
normals(array, optional) An array of floats that describe the normals of the model.
texCoords(mixed, optional) Can be an array of floats indicating the texture coordinates for the texture to be used or an object that has texture ids as
colors(array, optional) An array of colors in RGBA. If just one color is specified that color will be used for all faces.
pickingColors(array, optional) A custom set of colors to render the object to texture when performing the color picking algorithm.

Remarks

  • The Geometry class does not take a WebGLRenderingContext and is intentionally
  • The Geometry class holds the glTF2 "primitive" specification, although morph targets are not yet supported.