@luma.gl/webgl-state-tracker

@luma.gl/webgl-state-tracker

Provides WebGL context state tracking and a unified API for setting WebGL parameters

State tracking

This module installs overrides on a WebGLRenderingContext that track state changes and allow context state to be saved and restored through push and pop operations.

This is useful when combining code written in different WebGL frameworks or code bases, as each code base can make changes to the global WebGLRenderingContext state and leave it in a state that causes problems for the other code base.

Usage

yarn add @luma.gl/webgl-state-tracker

import trackContextState from '@luma.gl/webgl-state-tracker';

const gl = canvas.getContext('webgl');
trackContextState(gl);

Functions

trackContextState(gl : WebGLRenderingContext, options: Object)

Initialize WebGL state caching on a context. After calling this function, context state will be cached. State caching speeds up parameter access and enables pushContextState and popContextState to efficiently save and restore global WebGL context state.

trackContextState(gl, {enable = true, copyState} = {})

• gl (WebGLRenderingContext) - gl context
• enable (Boolean) - whether cache is being used
• copyState whether the state cache is initialized to WebGL defaults (fast) or read from the context (slow)

Remarks:

• trackContextState can be called multiple times to enable/disable state cache.
• copyState-false is fast, and yields correct results for newly created, unmodified contexts. If you are tracking a context created by an external framework, it is likely safest to use copyState=true to ensure the cache corresponds to the context state.

pushContextState(gl : WebGLRenderingContext)

Saves the current state of the context by "pushing" it onto an internal stack, enabling it to be restored later.

pushContextState(gl)

• gl (WebGLRenderingContext) - gl context Returns: nothing

Remarks:

• Can be called multiple times, enabling "nested" usage.
• Each invocation of pushContextState is expected to be matched by a call to popContextState at a later time.

popContextState(gl : WebGLRenderingContext)

Restores the state of the context at the time of the latest call to pushContextState.

popContextState(gl)

• gl (WebGLRenderingContext) - gl context Returns: nothing

Remarks;

• Any changes made to the context state after the last call to pushContextState are undone and "discarded".
• It is an error to call popContextState without first doing a matching call to pushContextState.

Remarks

• This a helper module for luma.gl, but is designed to be independently usable in other projects.

Changelog

7.4.0-alpha.1

• Add attribute picking to the picking module (#1268)