The same logic from D17025 is used in other places in the curve code.
This patch uses the class for the evaluated point offsets and the Bezier
control point offsets. This helps to standardize the behavior and make
it easier to read.
Previously the Bezier control point offsets used a slightly different standard
where the first point was the first offset, just so they could have the same
size as the number of points. However two nodes used a helper function
to use the same `OffsetIndices` system, so switch to that there too.
That requires removing the subtraction by one to find the actual offset.
Also add const when accessing data arrays from curves, for consistency.
Differential Revision: https://developer.blender.org/D17038
This changes how we access the points that correspond to each curve in a `CurvesGeometry`.
Previously, `CurvesGeometry::points_for_curve(int curve_index) -> IndexRange`
was called for every curve in many loops. Now one has to call
`CurvesGeometry::points_by_curve() -> OffsetIndices` before the
loop and use the returned value inside the loop.
While this is a little bit more verbose in general, it has some benefits:
* Better standardization of how "offset indices" are used. The new data
structure can be used independent of curves.
* Allows for better data oriented design. Generally, we want to retrieve
all the arrays we need for a loop first and then do the processing.
Accessing the old `CurvesGeometry::points_for_curve(...)` did not follow
that design because it hid the underlying offset array.
* Makes it easier to pass the offsets to a function without having to
pass the entire `CurvesGeometry`.
* Can improve performance in theory due to one less memory access
because `this` does not have to be dereferenced every time.
This likely doesn't have a noticable impact in practice.
Differential Revision: https://developer.blender.org/D17025
