gl-wiretap

A gl debugger that listens and replays gl (WebGL, WebGL2, and HeadlessGL) gpu commands

Example

const gl = glWiretap(realGL);
 
// do a bunch of webgl commands..
 
// then later, get all commands as a string of runnable javascript
const commands = gl.toString();
 
// possibly write commands to file, for unit testing or reproducing bug
require('fs').writeFileSync('./file.js',
    // create a `gl` variable for the script to use
    "const canvas = document.createElement('canvas');"
    + "const gl = canvas.getContext('webgl');"
    + commands
);

WebGL Usage

const canvas = document.createElement('canvas');
const realGL = canvas.getContext('webgl');
const gl = glWiretap(realGL);

WebGL2 Usage

const canvas = document.createElement('canvas');
const realGL = canvas.getContext('webgl2');
const gl = glWiretap(realGL);

HeadlessGL Usage

const { glWiretap } = require('gl-wiretap');
const realGL = require('gl')(1, 1);
const gl = glWiretap(realGL);

See the HeadlessGL project for more information on using it.

API

const gl = glWiretap(realGL, options);
 
// do a bunch of webgl commands..
 
// then later, see all commands ran
const commands = gl.toString();

glWiretap() methods

glWiretap().addComment()

Add a comment for later when calling glWiretap().toString(), to help human doing debugging

glWiretap().toString()

This is where the gl context outputs all values as runnable javascript. The value for context here is gl by default, for simplicity. But can be changed to the value of with options.contextName. Any variables created here (example: gl.createProgram(), or gl.createShader(gl.VERTEX_SHADER)) are simply constants that increment on an index to prevent collision.

glWiretap().checkThrowError()

Causes a thrown exception when error detected from gl context, to help human doing debugging

glWiretap().getReadPixelsVariableName()

Gets the last internal variable name used as a target value for gl.readPixels()

glWiretap().insertVariable(name, value)

Insert a value into the glWiretap() playback string.

glWiretap().reset()

Reset the playback string.

glWiretap().setIndent(spaces)

Set the playback indentation. Useful for formatting results.

glWiretap().getContextVariableName(value)

Get a variable name from the context. Useful for adding additional functionality to, for example, textures, etc.

glWiretap options

• contextName: String - A string that refers to the gl context for glWiretap().toString()
• recording: String[] - A array of strings that
• readPixelsFile: String - When set, writes a file by this name to the current directory when on node HeadlessGL using readPixels
• throwGetError: Boolean - Causes gl.getError() to throw if there is an error
• throwGetShaderParameter: Boolean - Causes gl.getShaderParameter() to throw if there is an error
• throwGetProgramParameter: Boolean - Causes gl.getProgramParameter() to throw if there is an error
• onReadPixels: Function(targetName, argumentAsStrings);
• onUnrecognizedArgumentLookup: Function(argument) => string - Allows for just in time value tracking and insertion.

Typescript support

By default, typescript is supported