Blender Git Loki

Cycles: Cleanup, split one gigantic function into two smaller ones

Fix compilation error with strict flags

Fix compilation error with strict flags and gcc-6

Cleanup/fix some BLI_string_utf8 not using size_t/off_t as expected.

Cleanup/fix last remnant usages of int instead of size_t for string length in BLI_string_utils.

D1873: Customize style for animation motion paths

New options to define the style of the animation paths in order to get
better visibility in complex scenes.

Now is possible define the color, thickness and several options relative
to the style of the lines used to draw motion path.

Cycles: Store time in BVH nodes

This way we can stop traversing BVH node early on.

Gives about 2-2.5x times render time improvement with 3 BVH steps.
Hopefully this gives no measurable performance loss for scenes with
single BVH step.

Traversal is currently only implemented for QBVH, meaning old CPUs
and GPU do not benefit from this change.

Cycles: Add option to split triangle motion primitives by time steps

Similar to the previous commit, the statistics goes as:

BVH Steps Render time (sec) Memory usage (MB)
0 46 260
1 27 373
2 18 598
3 15 826

Scene used for the tests is the agent's body from one of the barber
shop scenes (no textures or anything, just a diffuse material).

Once again this is limited to regular (non-spatial split) BVH,
Support of spatial split to this feature will come later.

Cycles: Add option to split curve motion primitives by time steps

The idea is to create several smaller BVH nodes for each of the motion
curve primitives. This acts as a forced spatial split for the single
primitive.

This gives up render time speedup of motion blurred hair in the cost
of extra memory usage. The numbers goes as:

BVH Steps Render time (sec) Memory usage (MB)
0 258 191
1 123 278
2 69 453
3 43 627

Scene used for the tests is the agent's hair from one of the barber
shop scenes.

Currently it's only limited to scenes without spatial split enabled,
since the spatial split builder requires some changes to work properly
with motion steps coordinates.

Cycles: Add utility function to calculate curve boundbox from given 4 keys

Also fixed some issues with motion keys calculation:

- Clamp lower and upper limits of curves so we can safely call those
functions for the very first and very last curve segment.
- Fixed wrong indexing for the curve radius array.
- Fixed wrong motion attribute offset calculation.

Cycles: Cleanup, trailing whitespace

Cycles: Split motion triangle file once again, avoids annoying forward declarations

Cycles: Move motion triangle intersection functions to own file

Mimics how regular triangles are working and makes it more clear where
the stuff is located in the kernel.

Needed to have some forward declarations because of the current placement
of things in the kernel.

Cycles: Cleanup, better variable name

Cycles: Add utility function to fetch motion keys while on CPU side

Cycles: Cleanup, comments

Cycles: Add utility function to fetch motion triangle when on CPU side

Cycles: Cleanup, delete trailing whitespace

Cycles: Fix compilation error on with older GCC

Hopefully it works on all platforms now.

Fix T50460. Greying out issue with Cycles culling options.