Add-ons may attempt to load the GPU module in background mode when no GPU
context has been initialized yet. This would give an error on import.
If then later the GPU context does get initialized, for example for a
render engine, import would still fail as the module is cached.
This reverts commit d7f124f06f, and again
throws errors in methods and constructors instead of module import.
Pull Request: https://projects.blender.org/blender/blender/pulls/123395
Motivation: When discussing with @Jeroen-Bakker and @aras_p about how to
approach sorting when rendering Gaussian splats in Blender, we realised that
compute shaders could help there (and have many other use cases), and that also
due to Blender 4.0 being on OpenGL >= 4.3, we can now rely on compute shaders
existing.
This PR is an initial pass for that functionality. It comes with a Python example, which
runs a compute shader and saves the output to a texture, which is then rendered in the
viewport.
There is no exposed support for storage buffers yet, but I expect I'll be able to work on
them soon if this is accepted.
The newly added parts are:
1. `gpu.compute.dispatch()`
2. a way set the compute source to `GPUShaderCreateInfo`: `shader_info.compute_source()`
3. a way to set the image store for `GPUShaderCreateInfo`: `shader_info.image()`
4. a way to set the `local_group_size` for `GPUShaderCreateInfo`: `shader_info.local_group_size(x,y,z)`
5. a way to get `max_work_group_size` from capabilities: `gpu.capabilities.max_work_group_size_get(index)`
6. a way to get `max_work_group_count` from capabilities: `gpu.capabilities.max_work_group_count_get(index)`
Pull Request: https://projects.blender.org/blender/blender/pulls/114238
