Blender Git Loki

Merge remote-tracking branch 'origin/blender2.8' into collada2.8

PyAPI: Make GPUVertFormat() argument optional

Merge branch 'blender2.8' of git.blender.org:blender into blender2.8

Merge branch 'collada' into blender2.8

GP: Add warning when mix Build and Time Offset

GP: Include option to render layers by view layer

This allows to make composition getting each grease pencil layer in a different render output.

Cycles: Overhaul ensure_valid_reflection to fix issues with normal- and bumpmapping

This function is supposed to prevent the black artifacts caused by strong normal- or bumpmapping, but failed in some cases.

Now the code correctly handles all test files and previous issues I am aware of and also has extensive comments describing
the algorithm and the math behind it.

Basically, the main problem was that there can be multiple valid solutions that fulfil the reflection angle criterium,
but I had assumed that only one would exist and therefore simply picked the first solution with a positive term in srqt().
Now, the code uses additional validity checks and a simple heuristic to pick the best valid solution.

Additionally, the code messed up very shallow reflections even if the normal map strength was zero due to the constant
limit for the outgoing ray angle, which caused shallow incoming rays to fail the initial test even when reflected directly
on Ng. Now, the code accounts for this by reducing the threshold in the case of a shallow incoming ray, ensuring that at
least N=Ng is always a valid solution.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D3816

Cleanup: comments and unused code

Tool System: draw circle-select brush outline

Tool System: support custom cursor drawing

PyAPI: initial gpu_extras module (circle drawing utility)

Merge remote-tracking branch 'remotes/origin/blender2.8' into soc-2018-npr

PyAPI: rename GPL VertBuf.attr_fill identifier to id

This is used elsewhere in the API and its a common abbreviation.

Depsgraph: don't lose the update tag on rebuild for op nodes with a name.

This fixes a missing update when clearing the Text On Curve
(follow_curve) option of a text object.

Cleanup: move params into their own struct

PyAPI: take paint-cursor space/region type args

WM: space, region type filtering for paint cursor

Avoids calling poll on mouse-move for unrelated space/region types.

PyAPI: support for Python paint cursors

Merge branch 'master' into blender2.8

WM: minor changes to cursor API