Blender Git Loki

GPUState: GPU_blend final API renaming

We now use GPU_blend for enabling / disabling blending and explicitly
set the blend equation.

Cleanup: GPUState: remove use of GPU_blend_set_func

Cleanup: GPUState: Replace blend func separate by enum

Cleanup: GPU: Move towards an explicit Blend state

This make use of the GLStateStack functions for:
- `GPU_blend()`
- `GPU_blend_set_func()`
- `GPU_blend_set_func_separate()`

The goal is to unify them using an explicit state setting.
This will remove the need to use obscure blend functions

GPUState: Add GL backend and state tracking but do not use it

This is just the backend work. It is not plugged in yet because it
needs more external cleanup/refactor.

Cleanup: GPU: Remove uneeded depth precision getter.

We always use 24bit framebuffers nowadays.

Cleanup: GPUState: remove float variant of GPU_scissor_get

GPUShader: Add debug labels

This allow better debugging inside renderdoc.

GPUShader: Add back vertformat_from_shader()

GPUShader: Improve auto name

Use macro to get calling function name. Helps debugging shaders.

GPUShader: Rewrite error printing

Now error printing only display the line related to the error.
We also put char marker if present.

Example:
```
-- Shader Compilation Errors : MAMaterial --

10414 | node_fresnel(, facingnormal, viewposition, tmp34);
| ^
| error: syntax error, unexpected ',', expecting ')'

----------------------------------
```

GPUShader: GL backend isolation

Cleanup: GPU: Replace Batch uniform by shader uniform using macro

This is a first step into removing uniforms from GPU_batch and Imm.

UI: Fix protential stray GPU state preventing correct drawing

Fix potential issue with nodetree introduced in rB47c6f41b8926.

GPencil: Replace Trace to use Empty images

Instead to use the Image Editor, now it uses the current selected Empty image

BLI_kdopbvh: Adjust epsilon according to the axis

This corrects the overlap detection for cloths since in this case kdop26
is used and epsilon represents the distance.

Merge branch 'master' into soc-2020-outliner

Depsgraph: simplify DEG_evaluate_* API

This mainly removes the bmain argument, which can be
retrieved from the graph itself.

Also, I removed some outdated/unnecessary comments.

Reviewers: sergey, sybren

Differential Revision: https://developer.blender.org/D8614

Sculpt: Enable Cloth Simulation Target for Pose and Boundary

This adds a new brush property called "Deformation Target" which
controls how the brush deformations is going to affect the mesh data. By
default is set to Geometry, which makes the brushes displace the
vertices. When set to Cloth Simulation, the deformation of the brush is
applied to the cloth solver constraints, so the simulation is
responsible to apply the final deformation. This allows to add cloth
simulation effects to other sculpt tools with minor modifications to their
code.

This patch enables Cloth Simulation deformation target for Pose and
Boundary brushes, which are tools that are already designed to work in
low poly counts and produce large deformations. This allows creating the
most common cloth effects, like bending and compressing folds, without
relying on collisions.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D8578

Sculpt: Erase Displacement Mesh Filter

Same concept as the Multires Displacement Eraser Brush but implemented
as a mesh Filter. This allows to delete the displacement of an entire
area uniformly.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D8608