This is a usefull feature that can be used to do a lot of precomputation on
the GPU instead of the CPU.
Implementation is simple and only covers the most usefull case.
How to use:
- Create shader with transform feedback.
- Create a pass with DRW_STATE_TRANS_FEEDBACK.
- Create a target Gwn_VertBuf (make sure it's big enough).
- Create a shading group with DRW_shgroup_transform_feedback_create().
- Add your draw calls to the shading group.
- Render your pass normaly.
Current limitation:
- Only one output buffer.
- Cannot pause/resume tfb rendering to interleave with normal drawcalls.
- Cannot get the number of verts drawn.
There are a few places where DerivedMesh is still used, most notably
when calling the (not yet ported) cloth simulation. There is also still
the use of Object.derivedDeform and Object.derivedFinal. Those places are
marked with a TODO.
Some functions in the editors module were copied to accept Mesh. Those
already had 'mesh' in the name; the copies are suffixed with '__real_mesh'
for easy renaming later when the DM-based functionality is removed.
Previously, the "layers_used" value was getting updated by the drawing code.
However, when using copy on write, the drawing code gets evaluated copies of
the armature data instead of the original data, so any updates here fail to
get flushed to the original data, hence the lack of updates in the UI.
Fixed by moving the calculation to RNA when setting bone layers, as it should
have been done originally. (The one downside to this is if we set individual
layer memberships one by one - this could be slower as the recalc would have to
happen each time this changes).
We can not rely on edit->psys, it is not set for particle edit,
and there is some logic deeper inside which does different things
dependent on that.
We need to replace those checks with some some HAIR vs. PARTICLES
flag and always set psys pointer.
The idea is that edit mode structure is owned by original object,
and used for drawing. This is a bit confusing, especially since
path cache is also in that structure and needs evaluated object
to calculate cache.
In the future we should split edit data from visualization data,
but that's bigger refactor.
Bone selection overlay is only available in pose mode.
and when active overrules the selection buffer.
This is currently `tricked` by switching the draw engines, but this is
an exception. Not sure how to solve this in a better way.
After this is solved we can look at how to localize the dim effect to only the objects connected to the active armatures. Currently it dims the whole screen (including background).
@campbellbarton I added you as reviewer as it you have done a lot in the DRW_draw_select_loop
Reviewers: campbellbarton, fclem
Reviewed By: fclem
Subscribers: campbellbarton
Tags: #bf_blender_2.8, #code_quest
Maniphest Tasks: T54983
Differential Revision: https://developer.blender.org/D3241
The actual code is a bit convoluted but allows good and "pseudo efficient"
drawing. (pseudo efficient because rendering instances with that amount of
vertices is really inneficient. We should go full procedural but need to
have bufferTexture implemented first) But drawing speed is not a bottleneck
here and it's already a million time less crappy than the old (2.79) immediate
mode method.
Instead of drawing actual wires with different width we render a triangle
fan batch (containing 3 fans: bone, head, tail) which is then oriented in
screen space to the bone direction. We then interpolate a float value
accross vertices giving us a nice blend factor to blend the colors and
gives us really smooth interpolation inside the bone.
The outside edge still being geometry will be antialiased by MSAA if enabled.
