Note: This still needs some copy-on-write magic to get the bone pointers
to get remapped properly (e.g. evaluated pose still refers to original
arm->bones, and arm->act_bone isn't getting remapped).
After copying animation data we need to re-map action, otherwise
our original DNA values will go out of symc, causing flickering
when tweaking values on animated node tree.
The idea is to re-use evaluated datablock from within current context.
This relies on the following factors:
- It expects scene to be fully evaluated before preview jobs starts.
- It expects datablocks to be localized.
The workaround removal was wrong, the whole id->adt of a local
copy is to be NULL.
But now instead of modifying original datablock, we tell library
manager to not copy animation data.
This was due to the background being drawn by a batch that had its VAO
generated in the windows "UI" context.
Since we use the DRW ogl context to draw the entire area, we have to
regenerate the VAO for thoses UI batches to be drawn correctly.
The actual weighting calculation is not smooth as the bone display.
The bone itself can be smooth for esthetic purpose but the distance display
should match the underlying weighting formula.
Past shader was too slow and had bad artifacts. This method is much simpler
and eficient and only exhibit some popping when the raidus of the head/tail
is changed.
We now use a more pleasant and efficient way to display enveloppe bones
and their radius.
For this we use a capsule geometry that is displaced (in the vertex shader)
to a signed distance field that represents the bone shape.
The bone distance radius are now drawn in 3D using a "pseudo-fresnel" effect.
This gives a better understanding of what is inside the radius of influence.
When capsules are not needed, we switch to default raytraced points.
The capsules are not distorded by the bone's matrix (same as their actual
influence radius) and are correctly displayed even with complex scaled
parents hierarchy.
