Blender Git Loki

Eevee: SSR: Add mipmap filtering and bias to reduce noise.

Also fix the roughness factors.

Eevee: Fix glossy node roughness.

Eevee: SSR: Don't block the ray if tracing behind object.

This requires to check for backface after a hit.

Eevee: SSR: Add per pixel resolve of multiple rays.

Eevee: SSR: Add roughness random rays.

Eevee: SSR: Add double buffer so we can read previous frame color.

Also add simple reprojection and screen fade to the SSR resolve pass.

Eevee: SSR: Make raymarch step bigger.

Eevee: Fix Shader compilation.

Eevee: SSR: Add simple raytracing.

Still imprecise.

Eevee: Fix clip/hashed alpha prepass/shadow crash.

Eevee: SSR: Encode Normal in buffer and add cubemap fallback.

Normals can point away from the camera so we cannot just put XY in the buffer and reconstruct Z later as we would not know the sign of Z.

Eevee: SSR: Output ssr datas to buffers.

Output in 2 buffers Normals, Specular Color and roughness.
This way we can raytrace in a defered fashion and blend the exact contribution of the specular lobe on top of the opaque pass.

Eevee: Ssr: Add ssr id to glossy nodes.

An id is given to each glossy node in order to determine which specular lobe is using ssr.

Fix T50039: texture paint soften strength not working with float images.

Initialize scene layer for evaluation context used by preview renderer

Ideally need to clean and sane and impossible-to-break way of making sure
evaluation context is fully initialized, but that would need some thoughts
and experimentation.

Render preview: Always make sure all ID datablocks references by objects are in bmain

Otherwise we'll have confused dependency graph builder, which wouldn't be able to
build proper graph.

Didn't find a way to avoid world copy here, we can probably escape with some shallow
copy here, but that will currently complicate code a lot.

Ideas to consider here:

- Use shallow copy of existing world after new ID management API is in place.

Downside would be thread safety, kind of nice to have everything local.

- Switch depsgraph away from ID_TAG and do hash lookup or so.

This will slow down depsgraph builder, but will make code more reliable.

Fix T51948: pen pressure not detected with some Wacom tablets.

Generalizes current conditions, QT implements it the same way.

Correct invalid assert use

Manipulator: view-selected support

Only applies to selected manipulators
(currently not used for regular manipulators).

Manipulator: Expose Context.manipulator_group

Needed for operators run by the manipulator keymap
so they can access their selected manipulators.