Blender Git Loki

[cmake] Add minimum python version check to cmake to prevent later build errors.

Code cleanup: simplify cmake kernel install.

Cycles: CUDA bicubic and tricubic texture interpolation support.

While cubic interpolation is quite expensive on the CPU compared to linear
interpolation, the difference on the GPU is quite small.

Code refactor: make texture code more consistent between devices.

* Use common TextureInfo struct for all devices, except CUDA fermi.
* Move image sampling code to kernels/*/kernel_*_image.h files.
* Use arrays for data textures on Fermi too, so device_vector<Struct> works.

Merge branch 'blender2.8' into greasepencil-object

Actually force accumulate mode for the Smear brush in weight/vertex paint.

Just removing the checkbox from UI isn't enough for proper behavior.

Make weight paint blur thread safe, and fix smear ignoring mirror.

Instead of trying to be clever with swaps and lazy updating the weight
data, simply recalculate one single array. To improve performance, use
threading for that.

Cleanup: style, duplicate includes

Cleanup: remove Py3.5 compatible code

Merge branch 'blender2.8' into greasepencil-object

Initial fix for T53014: Cycles material preview no light

This was introduced on 9ad2c0b6154.

Although this still doesn't fix the issue, it updates the preview
system to use COLLECTION_DISABLED as intended.

What is missing now is for the flushing to work effectively.

Eevee: Shadows: Add Contact Shadows

This add the possibility to add screen space raytraced shadows to fix light leaking cause by shadows maps.

Theses inherit of the same artifacts as other screenspace methods.

Eevee: Modify the raycast function to be more flexible.

Make quality a parameter, and modify the ray end to be premultiplied so that the raytrace is done on a range.

This is in order to add contact shadows.

Merge branch 'blender2.8' into topbar

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

Cycles: Fix possible race condition when generating Beckmann table

Two issues here:

- Checking table size to be non-zero is not a proper way to go here. This is
because we first resize the table and then fill it in. So it was possible that
non-initialized table was used.

Trickery with using temporary memory and then doing table.swap() might work,
but we can not guarantee that table size will be set after the data pointer.

- Mutex guard was useless, because every thread was using own mutex. Need to
make mutex guard static so all threads are using same mutex.

Fix crash when deleting workspace active in multiple windows

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

Add 'x' icon to active workspace tab to delete workspace

Icon could be a bit nicer, but is consistent with other places in the
UI. Code is also a bit hacky, as usual in interface handling...

Cycles: Cleanup, indendation