Blender Git Commits

New python submodule `mathutils.interpolate` for various mesh interpolation and weighting methods.

This module will contain mirrored functions for calculating and applying
weights for points on a mesh. This includes barycentric and UV weighting
and possibly more advanced global weighting such as harmonic weights.

The naming should follow this scheme:
<type>_{2d,3d}_{calc,apply}

e.g.
poly_2d_calc
poly_2d_apply
uv_3d_calc
...

Reviewers: campbellbarton

Differential Revision: https://developer.blender.org/D939

Fix for missing library linking in blenderplayer.

Another fix for particle instance child lookups, was not subtracting
parent amount.

Fix for invalid particle pointer access in mixed particle/child loop.

Better update function for particle settings affecting nested cloth
modifier.

Fix for applying the bending randomness factor.

A stupid hack is needed here, changing the way the factor is applied to
angular bending springs. In cloth sim the bending factor of individual
springs is applied as a mix value between the bending stiffness and a
max value, but this max value isn't even used in hair sim so that
approach becomes useless.

Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp

Randomness factor for hair bending stiffness.

This helps to create some variation in a hair system, which can
otherwise become very uniform and boring. It's yet another confusing
setting in a system that should have been nodified, but only option for
now (broken windows ...)

Conflicts:
source/blender/blenkernel/intern/particle_system.c
source/blender/physics/intern/BPH_mass_spring.cpp

Fix for particle instance initial frames.

These were not orthonormal and tended to flip with changing hair
direction, now use the particle hair matrix which is stable wrt. the
mesh surface.

Fix for particle instance modifier: use a stable parallel-transport
framing method instead of the Frenet frame.

The Frenet frame is very succeptible to sudden twists along straight
sections of a curve where the second derivative (curvature) becomes 0.

Nicer hashing functionality for sim debugging using a variadic macro
to support multiple hash identifiers.

Using explicit hashing functions for every sim debug call defeats the
purpose of having a quick feedback system. Now this can be done simply
by passing an arbitrary number of hash inputs (integers) at the end of
the function calls, which are then combined by a system of variadic
macros (based on the ELEM feature). Up to 8 identifiers are supported
currently, but more could be added easily if needed.

Conflicts:
source/blender/blenkernel/intern/particle_system.c
source/blender/physics/intern/BPH_mass_spring.cpp

Some tweaking of value ranges for hair target density and removed
density factor (already included in grid velocity).

Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp

Inverted effect of target density was unstable, the divergence term
needs to be substracted instead.

Use dedicated debug values in cloth settings instead of abusing unused
other values.

Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp

Fixed wrong stride values used for offsetting the index of Eigen values.

The Eigen solver for hair grids uses an extra margin of 1, which means
greater stride values.

Hair grid code was using an invalid hair segment at each hair end with
zero vectors, leading to bad density values.

Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp

A bunch of debug drawing changes.

Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp

Corrected the divergence and gradient calculation for the hair grid
solver input and output.

This uses the central difference method (instead of combined forward/
backward difference), which makes it easier to correctly account for
grid borders.

Fallback method for defining density in the hair grid using discrete
samples.

This is just an intermediate method to make sure the density is valid.
Eventually the closest-point method should be used, but for testing
the poisson solver this is easier to debug.

Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp

Added a margin to the number of cells used in the poisson grid solver,
to ensure we always have one layer of empty cells around the fluid.

Fix for merge errors and leftover unused code lines.