Implementation of the design task #142969.
This adds the following:
- Exact GPU interpolation of curves of all types.
- Radius attribute support.
- Cyclic curve support.
- Resolution attribute support.
- New Cylinder hair shape type.

What changed:
- EEVEE doesn't compute random normals for strand hairs anymore. These are considered legacy now.
- EEVEE now have an internal shadow bias to avoid self shadowing on hair.
- Workbench Curves Strip display option is no longer flat and has better shading.
- Legacy Hair particle system evaluates radius at control points before applying additional subdivision. This now matches Cycles.
- Color Attribute Node without a name do not fetch the active color attribute anymore. This now matches Cycles.
Notes:
- This is not 100% matching the CPU implementation for interpolation (see the epsilons in the tests).
- Legacy Hair Particle points is now stored in local space after interpolation.
The new cylinder shape allows for more correct hair shading in workbench and better intersection in EEVEE.
| | Strand | Strip | Cylinder |
| ---- | --- | --- | --- |
| Main |  |  | N/A |
| PR |  |  |  |
| | Strand | Strip | Cylinder |
| ---- | --- | --- | --- |
| Main |  | | N/A |
| PR | ||  |
Cyclic Curve, Mixed curve type, and proper radius support:

Test file for attribute lookup: [test_attribute_lookup.blend](/attachments/1d54dd06-379b-4480-a1c5-96adc1953f77)
Follow Up Tasks:
- Correct full tube segments orientation based on tangent and normal attributes
- Correct V resolution property per object
- More attribute type support (currently only color)
TODO:
- [x] Attribute Loading Changes
- [x] Generic Attributes
- [x] Length Attribute
- [x] Intercept Attribute
- [x] Original Coordinate Attribute
- [x] Cyclic Curves
- [x] Legacy Hair Particle conversion
- [x] Attribute Loading
- [x] Additional Subdivision
- [x] Move some function to generic headers (VertBuf, OffsetIndices)
- [x] Fix default UV/Color attribute assignment
Pull Request: https://projects.blender.org/blender/blender/pulls/143180
This prevents the use of unaligned data types in
vertex formats. These formats are not supported on many
platform.
This simplify the `GPUVertexFormat` class a lot as
we do not need packing shenanigans anymore and just
compute the vertex stride.
The old enums are kept for progressive porting of the
backends and user code.
This will break compatibility with python addons.
TODO:
- [x] Deprecation warning for PyGPU (4.5)
- [x] Deprecate matrix attributes
- [x] Error handling for PyGPU (5.0)
- [x] Backends
- [x] Metal
- [x] OpenGL
- [x] Vulkan
Pull Request: https://projects.blender.org/blender/blender/pulls/138846
Add back the deprecated format to avoid asserts.
GPU backends should still have the code to support them.
Also add deprecation warnings as these types will be
removed for 5.0.
Pull Request: https://projects.blender.org/blender/blender/pulls/139213
This promotes any INT_TO_FLOAT attribute to F32 and
to the float promotion inside python `attr_fill`.
We issue a deprecation warning when hitting this path.
Raise an error is the component type is not integer.
Pull Request: https://projects.blender.org/blender/blender/pulls/139206
This commit finishes removing the uses of the integer to float
vertex buffer fetch mode. Previous commits noted below already started
that process. The last usage was geometry attributes. Now integers are
converted to floats as part of the existing upload process.
The change makes the Vulkan vertex buffer type conversion unused, so
it's removed. That's nice because Vulkan vertex buffers go from 1040 to
568 bytes in size and have significantly less overhead on creation.
Related:
- 153abc372e
- 1e1ac2bb9b
- 617858e453
Pull Request: https://projects.blender.org/blender/blender/pulls/138873
This unifies vertex and texture data formats
into a single base enum class.
`TextureFormat` and `VertexFormat` then mask
the invalid format for their respective usage.
Having a base enum allows casting between
`TextureFormat` and `VertexFormat` possible
(needed for Buffer Textures).
It also makes it easier to write and read data
to buffers/textures as each format will have an
associated host type.
These enum is generated from MACRO expansion.
This allow to centralize all information about
the formats in one place. This avoid duplicating
the list of enums for each backend.
This only creates the new enum. Porting older enums will
be done in other PRs.
Normalized integer CPU format are missing and waiting for #130640
Rel #130632
Pull Request: https://projects.blender.org/blender/blender/pulls/138069
And slightly simplify two string processing functions in this API,
`GPU_vertformat_safe_attr_name` and `copy_attr_name`.
This makes the API easier to interface with from C++ code,
and can avoid unnecessary string length measurements.
Pull Request: https://projects.blender.org/blender/blender/pulls/134882
Move the code dealing with converting float3 to GPU normals
out of the vertex format header into a separate header. Use a
proper C++ namespace and remove duplication by only using
the more recently added C++ templated conversions.
Most of the diff comes from the removal of the indirect includes
from GPU_vertex_format.hh. A lot of files ended up mistakenly
depending on that.
Pull Request: https://projects.blender.org/blender/blender/pulls/134873