In order to experiment with different storage types for `DRW_Attributes`
and for general cleanup (see #103343). Also move a curves header to C++.
Pull Request #104716
Rewrite PBVH draw to allocate attributes into individual VBOs.
The old system tried to create a single VBO that could feed
every open viewport. This required uploading every color and
UV attribute to the viewport whether needed or not, often exceeding
the VBO limit.
This new system creates one VBO per attribute. Each attribute layout is
given its own GPU batch which is cached inside the owning PBVH node.
Notes:
* This is a full C++ rewrite. The old code is still there; ripping it out
can happen later.
* PBVH nodes now have a collection of batches, PBVHBatches, that keeps
track of all the batches inside the node.
* Batches are built exclusively from a list of attributes.
* Each attribute has its own VBO.
* Overlays, workbench and EEVEE can all have different attribute
layouts, each of which will get its own batch.
Reviewed by: Clement Foucault
Differential Revision: https://developer.blender.org/D15428
Ref D15428
This adds support for showing geometry passed to the Viewer in the 3d
viewport (instead of just in the spreadsheet). The "viewer geometry"
bypasses the group output. So it is not necessary to change the final
output of the node group to be able to see the intermediate geometry.
**Activation and deactivation of a viewer node**
* A viewer node is activated by clicking on it.
* Ctrl+shift+click on any node/socket connects it to the viewer and
makes it active.
* Ctrl+shift+click in empty space deactivates the active viewer.
* When the active viewer is not visible anymore (e.g. another object
is selected, or the current node group is exit), it is deactivated.
* Clicking on the icon in the header of the Viewer node toggles whether
its active or not.
**Pinning**
* The spreadsheet still allows pinning the active viewer as before.
When pinned, the spreadsheet still references the viewer node even
when it becomes inactive.
* The viewport does not support pinning at the moment. It always shows
the active viewer.
**Attribute**
* When a field is linked to the second input of the viewer node it is
displayed as an overlay in the viewport.
* When possible the correct domain for the attribute is determined
automatically. This does not work in all cases. It falls back to the
face corner domain on meshes and the point domain on curves. When
necessary, the domain can be picked manually.
* The spreadsheet now only shows the "Viewer" column for the domain
that is selected in the Viewer node.
* Instance attributes are visualized as a constant color per instance.
**Viewport Options**
* The attribute overlay opacity can be controlled with the "Viewer Node"
setting in the overlays popover.
* A viewport can be configured not to show intermediate viewer-geometry
by disabling the "Viewer Node" option in the "View" menu.
**Implementation Details**
* The "spreadsheet context path" was generalized to a "viewer path" that
is used in more places now.
* The viewer node itself determines the attribute domain, evaluates the
field and stores the result in a `.viewer` attribute.
* A new "viewer attribute' overlay displays the data from the `.viewer`
attribute.
* The ground truth for the active viewer node is stored in the workspace
now. Node editors, spreadsheets and viewports retrieve the active
viewer from there unless they are pinned.
* The depsgraph object iterator has a new "viewer path" setting. When set,
the viewed geometry of the corresponding object is part of the iterator
instead of the final evaluated geometry.
* To support the instance attribute overlay `DupliObject` was extended
to contain the information necessary for drawing the overlay.
* The ctrl+shift+click operator has been refactored so that it can make
existing links to viewers active again.
* The auto-domain-detection in the Viewer node works by checking the
"preferred domain" for every field input. If there is not exactly one
preferred domain, the fallback is used.
Known limitations:
* Loose edges of meshes don't have the attribute overlay. This could be
added separately if necessary.
* Some attributes are hard to visualize as a color directly. For example,
the values might have to be normalized or some should be drawn as arrays.
For now, we encourage users to build node groups that generate appropriate
viewer-geometry. We might include some of that functionality in future versions.
Support for displaying attribute values as text in the viewport is planned as well.
* There seems to be an issue with the attribute overlay for pointclouds on
nvidia gpus, to be investigated.
Differential Revision: https://developer.blender.org/D15954
Previously there was a special extraction process for "vertex colors"
that copied the color data to the GPU with a special format. Instead,
this patch replaces this with use of the generic attribute extraction.
This reduces the number of code paths, allowing easier optimization
in the future.
To make it possible to use the generic extraction system for attributes
but also assign aliases for use by shaders, some changes are necessary.
First, the GPU material attribute can now store whether it actually refers
to the default color attribute, rather than a specific name. This replaces
the hack to use `CD_MCOL` in the color attribute shader node. Second,
the extraction code checks the names against the default and active
names and assigns aliases if the request corresponds to a special active
attribute. Finally, support for byte color attributes was added to the
generic attribute extraction.
Differential Revision: https://developer.blender.org/D15205
Good side effect of the change is that it makes it so that the
size of an array is more likely to be calculated at a compile time.
More ideally we'll be using bli::Array instead of the bare array,
but that is outside of the scope of this change.
After this commit, all mesh data extraction and drawing code is in C++,
including headers, making it possible to use improved types for future
performance improvements and simplifications.
The only non-trivial changes are in `draw_cache_impl_mesh.cc`,
where use of certain features and macros in C necessitated larger
changes.
Differential Revision: https://developer.blender.org/D15088
