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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​

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

topology​

The draw mode, or primitive type.

Some options are triangle-list (default), triangle-strip, point-list, line-list.

attributes​

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

indices​

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.

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​

topology​

Follows glTF/OpenGL/WebGL conventions:

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.