This patch fixes T60171 by adding a dummy read from the `dummy` vertex attribute to `hair_get_pos_tan_binor_time` in `common_hair_lib.glsl`. Confirmed to work on my machine (macOS 10.14.4 Beta, Radeon R9 M295X).
According to my experiments regarding this issue, the problem is triggered when all of the following conditions are met: (a) the shader has no vertex reads; (b) the index buffer is ≥ 256KiB. I can't really give an explanation of this misbehavior because of the video driver's closed-source nature.
Reviewers: fclem
Reviewed By: fclem
Subscribers: zeddb
Maniphest Tasks: T60171
Differential Revision: https://developer.blender.org/D4490
This new system use transform feedback to compute subdivided hair points
position. For now no smoothing is done between input points.
This new system decouple the strands data (uv, mcol) with the points
position, requiring less update work if only simulation is running.
In the future, we can have compute shader do the work of the feedback
transform pass since it's really what it's meant to. Also we could generate
the child particles during this pass, releasing some CPU time.
draw_hair.c has been created to handle all of the Shading group creations
as well as subdivision shaders.
We store one final batch per settings combination because multiple viewport
or render could use the same particle system with a different subdivision
count or hair shape type.
