This is a dirty fix. A bit more cleaner approach would be to check if a
context is bound and delay the deletion only in this case.
Also we may want to do this orphan deletion at some other places than
wm_window_swap_buffers.
Do note that it does not match cycles implementation.
Also we could precompute the hash per strand before rendering but that would
suggest it's not per engine specific.
If we make the random value internal to blender then it won't be a matter
because other renderers will have access to the same value.
By default when moving a edge of the screen it always snaps to an invisible grid with unit of 4 pixels.
This was also affecting the snap to the midpoint and adjacent.
The solution was to make the snap to areagrid optional and use values of `origmin` and `origsize` that match the transformations in screen_edit.c.
This commit restores support for Motion Path drawing in 2.8 (as it wasn't ported over
to the new draw engines earlier, and the existing space_view3d/drawanimviz.c code was
removed during the Blender Internal removal).
Notes:
* Motion Paths are now implemented as an overlay (enabled by default).
Therefore, you can turn all of them on/off from the "Overlays" popover
* By and large, we have kept the same draw style as was used in 2.7
Further changes can happen later following further design work.
* One change from 2.7 is that thicker lines are used by default (2px vs 1px)
Todo's:
* There are some bad-level calls introduced here (i.e. the actgroup_to_keylist() stuff).
These were introduced to optimise drawing performance (by avoiding full keyframes -> keylist
conversion step on each drawcall). Instead, this has been moved to the calculation step
(in blenkernel). Soon, there will be some cleanups/improvements with those functions,
so until then, we'll keep the bad level calls.
Credits:
* Clément Foucault (fclem) - Draw Engine magic + Shader Conversion/Optimisation
* Joshua Leung (Aligorith) - COW fixes, UI integration, etc.
Revision History:
See "tmp-b28-motionpath_drawing" branch (rBa12ab5b2ef49ccacae091ccb54d72de0d63f990d)
Since the viewport header now supports transparency, text on pulldowns
can be hard to read if their color matches the viewport content.
Background is drawn using the 'inner' theme color, that was unused until now.
In some heavy rigs matrix inverse can be 10% of computation time. This
reduces it to 2% by using Eigen's optimized 4x4 matrix inverse and SSE
matrix multiplication.
