The code below has to handle the case when `sample_length` is greater
or equal to the total length already anyway, so we can just make that
a valid input. Currently, the snake hook brush for curves also makes
use of passing in larger sample lengths which current results in crashes
in debug builds.
This adds a new `Interpolate Curves` node. It allows generating new curves
between a set of existing guide curves. This is essential for procedural hair.
Usage:
- One has to provide a set of guide curves and a set of root positions for
the generated curves. New curves are created starting from these root
positions. The N closest guide curves are used for the interpolation.
- An additional up vector can be provided for every guide curve and
root position. This is typically a surface normal or nothing. This allows
generating child curves that are properly oriented based on the
surface orientation.
- Sometimes a point should only be interpolated using a subset of the
guides. This can be achieved using the `Guide Group ID` and
`Point Group ID` inputs. The curve generated at a specific point will
only take the guides with the same id into account. This allows e.g.
for hair parting.
- The `Max Neighbors` input limits how many guide curves are taken
into account for every interpolated curve.
Differential Revision: https://developer.blender.org/D16642
Use the newer more generic sampling and interpolation functions
developed recently (ab444a80a2) instead of the `CurveEval` type.
Functions are split up a bit more internally, to allow a separate mode
for supplying the curve index directly in the future (T92474).
In one basic test, the performance seems mostly unchanged from 3.1.
Differential Revision: https://developer.blender.org/D14621
This refactor had two main goals:
* Simplify the sampling code by using an algorithm with fewer special cases.
* Generalize the sampling to support non-sorted samples.
The `SampleSegmentHint` optimization was inspired by `ValueAccessor` from
OpenVDB and improves performance 2x in my test cases.
Differential Revision: https://developer.blender.org/D15348
lengths along a set of points. This can be used for the sample curves
node, or finding new points along a curve when extending
or shrinking it.
This commit uses it in the snake hook brush as an example.
The logic is similar to the uniform length sampling, but the next
sample length is retrieved from the input instead of multiplication.
For the sample node in the future, though this sort of sampling can be
potentially done more efficiently for specific curve types besides
poly curves, it's simpler, at least as a start, to work on a set of
evaluated points that can be treated like a poly curve.
Differential Revision: https://developer.blender.org/D14571
This commit adds calculation of lengths along the curve for each
evaluated point. This is used for sampling, resampling, the "curve
parameter" node, and potentially more places in the future.
This commit also includes a utility for calculation of uniform samples
in blenlib. It can find evenlyspaced samples along a sequence of points
and use linear interpolation to move data from those points to the
samples. Making the utility more general aligns better with the more
functional approach of the new curves code and makes the behavior
available elsewhere.
A "color math" header is added to allow very basic interpolation
between two colors in the `blender::math` namespace.
Differential Revision: https://developer.blender.org/D14382
