Empty (UDIM) tiles where drawn with a transparency checkerboard. They
should be rendered with a border background. The cause is that the image
engine would select a single area that contained all tiles and draw them
as being part of an image.
The fix is to separate the color and depth part of the image engine
shader and only draw the depths of tiles that are enabled.
Adding better support for drawing huge images in the image/uv editor. Also solved tearing artifacts.
The approach is that for each image/uv editor a screen space gpu texture is created that only contains
the visible pixels. When zooming or panning the gpu texture is rebuild.
Although the solution isn't memory intensive other parts of blender memory usage scales together with
the image size.
* Due to complexity we didn't implement partial updates when drawing images tiled (wrap repeat).
This could be added, but is complicated as a change in the source could mean many different
changes on the GPU texture. The work around for now is to tag all gpu textures to be dirty when
changes are detected.
Original plan was to have 4 screen space images to support panning without gpu texture creation.
For now we don't see the need to implement it as the solution is already fast. Especially when
GPU memory is shared with CPU ram.
Reviewed By: fclem
Maniphest Tasks: T92525, T92903
Differential Revision: https://developer.blender.org/D13424
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
Image engine is used to draw an image into a space. The current
structure wasn't clear and couldn't be easilly extended. This refactor
spliced the image draw engine into 3 main components.
- Space accessors: contains an interface to communicate with space data
(Image editor, UV Editor, Node Editor) in a common way. This reduced
the branching in the code base.
- DrawingMode: contains an interface to the used tactic to draw an image
inside the space framebuffer. Currently only one mode is implemented;
in the future there could be a separate drawing mode for huge images.
- ImageEngine: the core that connects the draw manager with the space
data and drawing mode.
