Blender Git Loki

Unified the main Eigen solver function a bit for constrained/unconstrained
solver variants.

Ported the remaining implicit solver functions for Eigen.

Also added a couple of utility wrapper functions for Eigen types to make
interfacing with plain float arrays and blenlib math easier.

Updating Eigen implicit dynamics solver implementation to adhere to the
new mass-spring solver API.

New hair editing feature "Shape Cut", for cutting hair based on a mesh
shape instead of a brush tool.

The brush cutting tool for hair, while useful, is not very accurate and
often requires rotating the model constantly to get the right trimming
on every side. This makes adjustments to a hair shape a very tedious
process.

On the other hand, making proxy meshes for hair shapes is a common
workflow. The new operator allows using such rough meshes as boundaries
for hair. All hairs that are outside the shape mesh are removed, while
those cutting it at some length are shortened accordingly.

The operator can be accessed in the particle edit mode toolbar via the
"Shape Cut" button. The "Shape Object" must be set first and stays
selected as a tool setting for repeatedly applying the shape.

Merge branch 'master' into gooseberry

Merge branch 'master' into gooseberry

Conflicts:
source/blender/blenlib/BLI_math_matrix.h
source/blender/blenlib/intern/math_matrix.c
source/blender/editors/object/object_bake_api.c

Reorganizing hair dynamics UI layout a bit to make settings slightly
more intuitive.

Also removed a couple of unused or useless features from the UI:
* collider friction is unused and replaced in favor of true collision
* spring damping refers to structural springs (stretch), which is
not noticable in hair due to extreme stiffness atm.
* pressure factors are not sure since this feature is too unstable atm.

Disabled the hair preview feature in the code, due to limited usefulness.

Interpolating hairs in a meaningful way is a quite difficult problem.
It works ok-ish for child hairs as long as they don't move, but with
motion the direction of interpolated hairs can become quite nonsensical
quickly.

Probably a better way to create simulation previews is to limit
simulation to a particular well-defined area (like render preview
borders), but run it in full detail in that area. The error from
omitting some interaction should still be much less than orientation
errors from interpolation.

Correctly downsample circles of confusion and use parallelism to do it
more efficient.

Second pass, blurs the downsampled buffer once.

Use the correct shaders and varyings

Viewport DOF:

* Scons builds correctly
* Separate vertex shader file for DOF, will make handling main easier
* Downsample color buffer + blur it. Circle of confusion is calculated
from zplane instead of length of distance from camera.

First ping pong between low resolution buffers working. Nice landmark
for working code.

Also cleanup unused variables and do not bind the same texture to two slots
(blurred texture is going to be different anyway)

Framebuffer compositing:

* Cleanup compositing buffers better when not needed.

* Support passes for the dof effect through defines in main - easy
solution to allow not having too many files for one shader effect.

SSAO and DOF work well together now.

Code that enables simultaneous DOF-SSAO effect. There's some sort of
texture coordinate offset still.

Use optimized view space reconstruction for ortho case as well.

Add a library file for projection shader code, should enable us to use
optimized position calculation again - relevant for both SSAO and DOF

More attempts to synchronize viewport and camera dof - probably will
need fixes in the rendering systems. Reserve textures for the dof
effect.

Moved render simplification function for particle distribution into the
distribution code.