Move the weight paint drawing to the fragment shader. The shader
uses a texture that uses the U.coba_weight custom color band, or
an internal color band.
In addition to actual weights, the shader has to display two
alert colors: missing vertex group, and zero weight. The zero
weight alert has to be blended with regular weight colors,
so that a single alert vertex surrounded by weighted ones is
still visible.
Reviewers: campbellbarton, fclem
Differential Revision: https://developer.blender.org/D3675
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)
