This PR introduces the concept of primitive expansion draws.
This allows to create a drawcall that will generate N amount of new
primitive for an original primitive in a `gpu::Batch`. The intent is to
phase out the use of geometry shader for this purpose.
This adds a new `Frequency::GEOMETRY` only available for SSBOs.
The resources using this will be fed the current `gpu::Batch` VBOs
using name matching.
A dedicated slot is reserved for the index buffer, which has its own
internal lib to decode the index buffer content.
A new attribute lib is added to ease the loading of unaligned attribute.
This should be revisited and made obsolete once more refactor
lands.
It is similar to the Metal backend SSBO vertex fetch path but it is
defined on a different level. The main difference is that this PR is
backend independant and modify the draw module instead of the GPU
module. However, it doesn't cover all possible attribute conversion
cases. This will only be added if needed.
This system is less automatic than the Metal backend one and needs
more care to make sure the data matches what the shader expects.
The Metal system will be removed once all its usage have been
converted.
This PR only shows example usage for workbench shadows. Cleanup PRs
will follow this one.
Rel #105221
Pull Request: https://projects.blender.org/blender/blender/pulls/125782
d712f91881