ezhangle / headless-gl

Creates WebGL contexts without making windows

headless-gl

This is a gutted version of node-webgl with no external dependencies, DOM emulation or window handling. You can use it to create WebGL contexts for GPGPU programming and server-side rendering in node. It should also work in browsers that support WebGL.

Dependencies

• Opengl
• GLEW (if running on Linux)

Installation

Just do:

npm install gl

Currently only works on OS X and Linux. If you have access to working Windows system and want to contribute, please let me know.

Usage

To get a handle on the headless OpenGL context, just do:

var gl = require("gl");

Then you can use all the ordinary WebGL methods.

Example

Here is an example that creates an offscreen framebuffer, clears it to red, reads the result and writes the image to stdout as a PPM :

//Create context
var width   = 64;
var height  = 64;
var gl = require("gl").createContext(width, height);

//Create texture
var tex = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, tex)
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, width, height, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);

//Create frame buffer
var fbo = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, tex, 0);

//Clear screen to red
gl.clearColor(1.0, 0.0, 0.0, 1.0);
gl.clear(gl.COLOR_BUFFER_BIT);

//Write output
var pixels = new Uint8Array(width * height * 3);
gl.readPixels(0, 0, width, height, gl.RGB, gl.UNSIGNED_BYTE, pixels);
process.stdout.write(["P3\n# gl.ppm\n", width, " ", height, "\n255\n"].join(""));
for(var i=0; i<pixels.length; ++i) {
    process.stdout.write(pixels[i] + " ");
}

Multiple Contexts

You can create multiple WebGL contexts if you like. To do this, just call:

var my_context = gl.createContext();

Which will work just like any other WebGL context. To get rid of a context when you are done with it, jst call destroy() on it:

my_context.destroy();

Why use this thing instead of node-webgl?

It depends on what you are trying to do. node-webgl is good if you are making a graphical application like a game. On the other hand, because headless-gl does not create any windows, it is suitable for running in a server environment. This means that you can use it to generate figures using OpenGL or perform GPGPU computations using shaders.

Credits

See LICENSES