Blender Git Loki

Implement velocity based adaptive step size calculation

Implement usage of dt property (preparation for adaptive time steps)

Use impulse clustering for self collisions

Also adjust impulse scaling to work better with the new clustering.

Use optimized approximated impulse clustering

Implement directional cluster based impulse pruning

Optimization: Use inertial solve for pre-collision

Instead of doing a full implicit pre-collision solve, do a simple
inertial solve (avance using velocities from previous step), this saves
time by doing one less solve per step, and also improves resting
stability by eliminating the influence of external forces disturbing the
mesh in contacting areas.

This improves general cloth performance by about 30-40% in relation to
the new cloth code, and improves performance by about 3 times in
relation to the original cloth code. This also makes collisions more
reliable by removing the need for positional interpolation, and thus
decreases the number of subframes required for a successful solve.

Optimization: Use static BVH for collision intersection

No need to use moving BVH for intersection checking, as in the end
collisions are only evaluated at the next state anyway, so can use
static BVH to reduce the amount of intersections to check.

Moving BVH will only make sense if ccd is implemented.

Use pre-solved locations for col response evaluation

Bring back impulse scaled repulses

It seems I was a bit too optimistic in thinking that just distance based
repulses could handle contacts nicely. Turns out impulse scaled repulses
really have enough of an influence in making the collision response more
effective, that it is worth keeping it for now, even if at the cost of a
very slight stability reduction and and a bit of an increase in
collision elasticity.

I hope to come up with a better solution, and elliminate this, after
cluster based impulse pruning is implemented.

Fix regression on sewing springs caused by plasticity

Remove epsilon from velocity conditional.

Also added a comment about the wrong duplicate impulse elimination being
used.

Fix mistake with backside relative velocities

also removed unused include...

Enable compression springs for hair

Clean-up some collision data allocation stuff

Self collision pointer logic has been simplified and allocations
reduced, as it only collides with one object (self).

Also, allocation size for all collisions has been reduced to 1/4,
because it was allocating extra space for deprecated stuff.

Implement self col groups for new self col system

Remove edgeset stuff (no longer used)

Remove unused selfbvh stuff

Move use_normal to col object settings (was in cloth settings)

Use proper friction property for self col and redesign col UI

Separate self collision distance from object collision distance