PPM does not store alpha channel, but TIFF does. We add a method to export RGBA to a TIFF file without compression. We add the corresponding options to gltf_viewer and AutomationEngine. The default export format for both gltf_viewer and AutomationEngine is now TIFF.
Rendering Difference Test
We created a few scripts to run gltf_viewer and produce headless renderings.
This is mainly useful for continuous integration where GPUs are generally not available on cloud machines. To perform software rasterization, these scripts are centered around Mesa's software rasterizers, but nothing bars us from using another rasterizer like SwiftShader. Additionally, we should be able to use GPUs where available (though this is more of a future work).
The script run.py contains the core logic for taking input parameters (such as the test
description file) and then running gltf_viewer to produce the results.
In the test directory is a list of test descriptions that are specified in json. Please see
sample.json to parse the structure.