In the original design draw engines had to copy with a limitation that
they were not allowed to reuse complex data structures between drawing
calls. Data that could be reused were limited to:
- GPUFramebuffers
- GPUTextures
- Memory that could be removed calling MEM_freeN (storage list)
- DRWPass
This is fine when the storage list contains arrays or structs but when
more complex data types (vectors, maps) etc wasn't possible.
This patch adds instance_data that can be reused between drawing calls.
The instance_data is controlled by the draw engine and doesn't need to
be limited as described above.
When an engines stores instance_data it must implement the
`DrawEngineType.instance_free` callback to free the data.
The patch originates from eevee rewrite. But was added to master as the
image engine rewrite also has a need for it.
Reviewed By: fclem
Differential Revision: https://developer.blender.org/D13425
This is a necessary step for EEVEE's new arch. This moves more data
to the draw manager. This makes it easier to have the render or draw
engines manage their own data.
This makes more sense and cleans-up what the GPUViewport holds
Also rewrites the Texture pool manager to be in C++.
This also move the DefaultFramebuffer/TextureList and the engine related
data to a new `DRWViewData` struct. This struct manages the per view
(as in stereo view) engine data.
There is a bit of cleanup in the way the draw manager is setup.
We now use a temporary DRWData instead of creating a dummy viewport.
Development: fclem, jbakker
Differential Revision: https://developer.blender.org/D11966
