Context

Members

antialias : Boolean

true if the WebGL context supports antialiasing. By defaultantialiasing is requested, but it is not supported by all systems.

cache : Object

A cache of objects tied to this context. Just before the Context is destroyed,destroy will be invoked on each object in this object literal that hassuch a method. This is useful for caching any objects that might otherwisebe stored globally, except they're tied to a particular context, and to managetheir lifetime.

defaultCubeMap : CubeMap

A cube map, where each face is a 1x1 RGBA texture initialized to[255, 255, 255, 255]. This can be used as a placeholder cube map whileother cube maps are downloaded.

defaultFramebuffer : Object

Gets an object representing the currently bound framebuffer. While this instance is not an actualFramebuffer, it is used to represent the default framebuffer in calls toTexture.FromFramebuffer.

defaultTexture : Texture

A 1x1 RGBA texture initialized to [255, 255, 255, 255]. This canbe used as a placeholder texture while other textures are downloaded.

depthTexture : Boolean

true if WEBGL_depth_texture is supported. This extension providesaccess to depth textures that, for example, can be attached to framebuffers for shadow mapping.

See:

• WEBGL_depth_texture

drawBuffers : Boolean

true if the WEBGL_draw_buffers extension is supported. Thisextensions provides support for multiple render targets. The framebuffer object can have mutiplecolor attachments and the GLSL fragment shader can write to the built-in output array gl_FragData.A shader using this feature needs to explicitly enable the extension with#extension GL_EXT_draw_buffers : enable.

See:

• WEBGL_draw_buffers

drawingBufferHeight : Number

The drawingBufferHeight of the underlying GL context.

See:

• drawingBufferHeight

drawingBufferWidth : Number

The drawingBufferWidth of the underlying GL context.

See:

• drawingBufferWidth

elementIndexUint : Boolean

true if the OES_element_index_uint extension is supported. Thisextension allows the use of unsigned int indices, which can improve performance byeliminating batch breaking caused by unsigned short indices.

See:

• OES_element_index_uint

etc1 : Boolean

true if WEBGL_texture_compression_etc1 is supported. This extension providesaccess to ETC1 compressed textures.

See:

• https://www.khronos.org/registry/webgl/extensions/WEBGL_compressed_texture_etc1/

floatingPointTexture : Boolean

true if OES_texture_float is supported. This extension providesaccess to floating point textures that, for example, can be attached to framebuffers for high dynamic range.

See:

• OES_texture_float

fragmentDepth : Boolean

true if the EXT_frag_depth extension is supported. Thisextension provides access to the gl_FragDepthEXT built-in output variablefrom GLSL fragment shaders. A shader using these functions still needs to explicitly enable theextension with #extension GL_EXT_frag_depth : enable.

See:

• EXT_frag_depth

instancedArrays : Boolean

true if the ANGLE_instanced_arrays extension is supported. Thisextension provides access to instanced rendering.

See:

• https://www.khronos.org/registry/webgl/extensions/ANGLE_instanced_arrays

memoryThreshold : Number

设置场景总的显存资源占用阈值，默认值：4G,单位GB。根据机器内存显存大小适当调整这个值，避免因资源占满导致崩溃。

options

Example:

{
  webgl : {
    alpha : false,
    depth : true,
    stencil : false,
    antialias : true,
    premultipliedAlpha : true,
    preserveDrawingBuffer : false,
    failIfMajorPerformanceCaveat : true
  },
  allowTextureFilterAnisotropic : true
}

pvrtc : Boolean

true if WEBGL_texture_compression_pvrtc is supported. This extension providesaccess to PVR compressed textures.

See:

• https://www.khronos.org/registry/webgl/extensions/WEBGL_compressed_texture_pvrtc/

s3tc : Boolean

true if WEBGL_texture_compression_s3tc is supported. This extension providesaccess to DXT compressed textures.

See:

• https://www.khronos.org/registry/webgl/extensions/WEBGL_compressed_texture_s3tc/

standardDerivatives : Boolean

true if the OES_standard_derivatives extension is supported. Thisextension provides access to dFdx, dFdy, and fwidthfunctions from GLSL. A shader using these functions still needs to explicitly enable theextension with #extension GL_OES_standard_derivatives : enable.

See:

• OES_standard_derivatives

stencilBits : Number

The number of stencil bits per pixel in the default bound framebuffer. The minimum is eight bits.

See:

• glGet with STENCIL_BITS.

stencilBuffer : Boolean

true if the WebGL context supports stencil buffers.Stencil buffers are not supported by all systems.

vertexArrayObject : Boolean

true if the OES_vertex_array_object extension is supported. Thisextension can improve performance by reducing the overhead of switching vertex arrays.When enabled, this extension is automatically used by VertexArray.

See:

• OES_vertex_array_object

Methods

createPickId(object) → Object

Creates a unique ID associated with the input object for use with color-buffer picking.The ID has an RGBA color value unique to this context. You must call destroy()on the pick ID when destroying the input object.

Name	Type	Description
object	Object	The object to associate with the pick ID.

Returns:

A PickId object with a color property.

Throws:

• RuntimeError : Out of unique Pick IDs.

Example:

this._pickId = context.createPickId({
  primitive : this,
  id : this.id
});

See:

• Context#getObjectByPickColor

getObjectByPickColor(pickColor) → Object

Gets the object associated with a pick color.

Name	Type	Description
pickColor	Color	The pick color.

Returns:

The object associated with the pick color, or undefined if no object is associated with that color.

Example:

var object = context.getObjectByPickColor(pickColor);

See:

• Context#createPickId