Blender Git Commits

Removed unused "collider grid" struct from hair volumetrics.

This is a leftover from previous approach of hair collisions (with
insufficient results). The hair volumetrics actually implements
"collision" with solid objects as well, but uses a Neumann boundary
condition on the main grid for this purpose.

Better grid rasterization method for hair volumetric grids.

This is based on the paper
"Detail Preserving Continuum Simulation of Straight Hair"
(McAdams, Selle, Ward, 2009)

The main difference is that hair line segments are used rather than only
rasterizing velocity at the vertices. This gives a much better coverage
of the hair volume grid, otherwise gaps can be produced at smaller grid
cell sizes and the distribution is uneven along the hair curve.

The algorithm for rasterizing is a variation of Bresenham's algorithm
extended onto 3D grids.

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

New debug element "circle" for simulations, which is quite useful for
visualizing scalar fields.

Debug grid drawing for hair volume was drawing one subdivision too many.

Unused leftover debug variable.

Reimplemented the voxel texture type for displaying hair continuum grids.

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

Expose hair grid info in the RNA (read-only); it can be useful for
debugging purposes.

Debug visualization code of a slice of the hair velocity vector field.

Removed arbitrary factor 2.0 on volumetric hair friction factor.

This was introducing energy into the system for any factor beyond 0.5
and caused major instability.

Fill the hair volume grid with the _new_ velocities from the first
solver step, instead of using the previous step's velocities.

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

Debug drawing feature to visualize the hair continuum grid.

Perform grid-based velocity smoothing for hair outside of the implicit
solver step.

Calculating forces and jacobians from linearly interpolated grid values
is problematic due to discontinuities at the grid boundaries. The new
approach of modifying velocities after the backward euler solver step
was suggested in a newer paper

"Detail Preserving Continuum Simulation of Straight Hair"
(McAdams, Selle 2009)

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

Minor fix for lost variable declaration during cherry-picking.

Fix for warnings/errors

Conflicts:
source/blender/blenkernel/intern/key.c
source/blender/blenkernel/intern/particle_system.c
source/blender/makesrna/intern/rna_particle.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.

Conflicts:
release/scripts/startup/bl_ui/properties_particle.py

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

Removed unused variable.

A little bit of code sanity by splitting particle distribution function
by type.

Instead of squashing totally unrelated code into the same monster
function.

Moved particle code for distributions into own file to make hacking
easier.

This code is badly broken and needs to be replaced, but at least having
a workable code structure might help with quick hacks to fix the worst
cases.

Removed unused line.