Cubegen

A Bash scripting wrapper around cmgen, an image-based lighting asset generator, included in Filament.

Cubegen outputs the following files:

cmgen outputs both prefiltered and non-prefiltered HDR faces mips [m0 - m8] (256x256 - 1x1). By using a combination of the prefiltered and non-prefiltered face you can get a more gradual transition between the different mip levels. The outputted faces are made seamless through cmgen by duplicating a row of pixels to the bottom or a column to the right of each face that don't have an adjacent face in the image (the duplicate is taken from the adjacent face in the cubemap). This is because when accessing an image with bilinear filtering, we always overshoot to the right or bottom. This technique works well with cubemaps stored as a cross in memory.

All HDR faces are packed in a single .binpack file. Binpacking is an efficient way of packing textures without the downsides of texture atlases. For more information please refer to the Binpack documentation. The .binpack file can efficiently be loaded and parsed in a web worker. An example implementation can be found in main.js.

Demo

Live demo

Installation

Cubegen does not ship the cmgen binary due to licence concerns and seeing as the Filament is in active development it would be good to keep up to date with the latest changes.

Automatically set up for MacOS:

$ ./setup_macos.sh

Or please follow the following instructions:

Install Node.js and install node_modules using npm.

$ npm install

Create an input, output and bin directory in the root of the project.

Download the latest stable release or nightly build from Filament and move the cmgen binary from ./bin/filament/bin/cmgen in Filament to bin in this project.

Usage

$ ./run.sh <input>

Resources

A very good resource for free CC0 HDRI's is https://hdrihaven.com/.

Licence

cubegen is released under the MIT licence. The included HDR image has been downloaded from HDRI Haven and is released under the CC0 licence.

williammanco/cubegen