Blender Git Loki

Write out sim debug data along with dupli caches, if the global sim
debug flag is enabled.

SimDebugData writer/reader for Alembic caches.

This will allow debug visualization data to be stored inside caches
along the actual simulation state.

While the regular simulation allows examining simulation data on-the-fly
by stepping through the regular timeline, the new baking mechanism used
for caches does not easily allow simulation data to be visualized frame
by frame. Caching this data will allow adding it to the global sim debug
data.

This would also still be very handy if the baking process itself becomes
more interactive again. Unlike the current simulation progression, the
cached data can be accessed randomly, so scrubbing throught the timeline
becomes possible.

Fixed unused parameter warnings in Alembic customdata code.

Added the major parameters for the hair simulation.

This is basically copied from existing cloth sim settings, with a good
deal of cleanup and sanitization.

Unlike cloth parameters, the damping values are described as relative
to their associated stiffness values for springs. This is much easier
to use in practice and less prone to lead to unstable simulations.
Damping simply works best when the force is in the same order of
magnitude as the stiffness, so having a relative factor requires much
less adjustment on the user side.

Added effector weights for cache hair simulation.

RNA for modifier struct subtypes.

Also renamed StrandSimParams to HairSimParams, since strands are only
the agnostic data structure, while these parameters are specifically
used to simulate hair-like behavior. Other simulations could use strands
but implement completely different kinds of physics (e.g. grass, ropes).

"Structural" spring forces for strands.

These connect strand points to ensure constant length and form the main
spring system in strand simulation.

Note that parameters are still hardcoded.

Fix unfreed motion state memory when freeing strand data.

Scalp animation support: copy strand root locations from the rest pose
before performing a time step.

Pinning for strand roots.

Note that roots are currently not animated.

Use FPS value to sync the strand simulation time with the render time.

Additionally the time can be scaled using the timescale parameter.

Correct progression handling of the strands motion state through cache
baking.

For now this simply applies gravity and applies the basic hair solver
for velocities and positions.

Fix for wrong pointer used in the modifier cache copy function.

Force calculation function for strands (only gravity atm).

Sanity check and nicer substep loop for strands simulation.

Fixed writing code for cache modifiers to include extra DNA fields of
subtypes.

Fixed DupliCache writers/readers to support subsequent stages of
cache manipulation.

Strand data in caches is now stored in a named list, so we can avoid
adding strand data in every frame.

Merge branch 'master' into alembic

cleanup: warning

Clear duplilist instances when reading from a dupli cache, to avoid
generating a new dupli instance on every frame.