Two were actual bugs, though they existed only in unused code:
* In Freestyle it was unintentionally copying a scene rather than referencing it.
* In BLI_array_store_is_valid there was use of uninitialized memory.
changes in BLI_kdopbvh:
- `BLI_bvhtree_find_nearest_to_ray` now takes is_ray_normalized and scale argument.
- `BLI_bvhtree_find_nearest_to_ray_angle` has been added (use for perspective view).
changes in BLI_bvhutils:
- `bvhtree_from_editmesh_edges_ex` was added.
changes in math_geom:
- `dist_squared_ray_to_seg_v3` was added.
other changes:
- `do_ray_start_correction` is no longer necessary to snap to verts.
- the way in which the test of depth was done before is being simulated in callbacks.
So the error seems to be in cubic_tangent_factor_circle_v3(),
which was introduced with D2001.
I've tweaked the most obvious culprit here - the epsilon factor.
It used to be 10^-7, but I've reduced it down to 10^-5 now,
and it's looking a lot more stable now :)
---------
BTW, about the derivation of the magic 0.390464 factor I briefly subbed back
as a workaround for this bug, see:
http://www.whizkidtech.redprince.net/bezier/circle/
Regression from recent rB2c5dc66d5effd4072f438afb, if last item of last chunk of a mempool was valid,
it would not be returned by mempool iterator step, which would always return NULL in that case.
Together with the extended loop callback and userdata_chunk, this allows to perform
cumulative tasks (like aggregation) in a lockfree way using local userdata_chunk to store temp data,
and once all workers have finished, to merge those userdata_chunks in the finalize callback
(from calling thread, so no need to lock here either).
Note that this changes how userdata_chunk is handled (now fully from 'main' thread,
which means a given worker thread will always get the same userdata_chunk, without
being re-initialized anymore to init value at start of each iter chunk).
