This patch adds initial curve support to geometry nodes. Currently
there is only one node available, the "Curve to Mesh" node, T87428.
However, the aim of the changes here is larger than just supporting
curve data in nodes-- it also uses the opportunity to add better spline
data structures, intended to replace the existing curve evaluation code.
The curve code in Blender is quite old, and it's generally regarded as
some of the messiest, hardest-to-understand code as well. The classes
in `BKE_spline.hh` aim to be faster, more extensible, and much more
easily understandable. Further explanation can be found in comments in
that file.
Initial builtin spline attributes are supported-- reading and writing
from the `cyclic` and `resolution` attributes works with any of the
attribute nodes. Also, only Z-up normal calculation is implemented
at the moment, and tilts do not apply yet.
**Limitations**
- For now, you must bring curves into the node tree with an "Object
Info" node. Changes to the curve modifier stack will come later.
- Converting to a mesh is necessary to visualize the curve data.
Further progress can be tracked in: T87245
Higher level design document: https://wiki.blender.org/wiki/Modules/Physics_Nodes/Projects/EverythingNodes/CurveNodes
Differential Revision: https://developer.blender.org/D11091
This is just linear interpolation, but it's nice to have an equivalent
to `mix3` for only two values. It will be used for interpolation of
values between bezier spline control points.
This patch adds support for accessing corner attributes on the point domain.
The immediate benefit of this is that now (interpolated) uv coordinates are
available on points without having to use the Point Distribute node.
This is also very useful for parts of T84297, because once we have vertex
colors, those will also be available on points, even though they are stored
per corner.
Differential Revision: https://developer.blender.org/D10305
If the mesh has any corner or point attributes (e.g. vertex weights or
uv maps), those attributes will now be available on the generated points
as well.
Other domains can be supported as well. I just did not implement those yet,
because we don't have a use case for them.
Differential Revision: https://developer.blender.org/D10114
Hans Goudey
Jacques Lucke
Campbell Barton