Blender Git Loki

Cloth: Fix the shrink feature to be controlled by the sewing spring flag.

Previously it was all over the place: without a vertex group it was
always enabled, and with it it depended on the Self Collision option
due to a likely editing mistake. Now it should be in sync with what
disables the fields in the UI.

The verts->shrink_factor field is changed to just cache the vertex
weight, with the shrink_min/shrink_max interpolation done later.
This is because cloth_apply_vgroup only runs if there are vertex
groups, and thus the factor may not update after property changes.

In addition, bending springs are now also affected by the shrink
factor to avoid visible distortion in object shape at high shrink.

Cloth: Invalidate cache when sewing springs are toggled on or off.

Force Fields: Fix Texture with both Use Coordinates and 2D enabled.

From description, Use Coordinates evaluates the texture using
target coordinates in the local space of the force field object.
2D is supposed to ignore the Z coordinate. Thus one would assume
that if both are enabled, the force field effect would move with
the force field object, and Z would be 0.

However, instead first the 2D option projects points onto a plane
passing through the global zero and orthogonal to the local Z,
and only then the resulting point is transformed into local space.
Z is not locked at 0, so procedural textures like Spherical Blend
don't work as expected.

To fix this, apply local transform first, and then just clear Z if 2D.

Implement threaded partial display buffer update

This speeds up update of display buffer when affected area is big enough.

Mainly helpful for cases when doing long fast strokes when painting.

Cleanup: warnings

Values set but not used

Fix T48356: Bridge tool creates self-intersecting loop

When loops are planar to eachother, initialize their winding based on surrounding geometry.

Fix error bridging edge loops flipping

Calculating the winding failed when faces exist on both sides of the edge.

Cycles: Comment out unused function arguments

Multi-thread generated image creation

Gives about 2x speedup on laptop when creating new hires generated image,
regardless of it's type (color, color grid, uv grid).

Correct snap checks for edges & faces

Snap targets can't contain vertices which are being transformed

Don't overwrite existing snap context

Re-activating transform would overwrite previous context, leaking memory.

Cleanup: style

Missed last commit

bvhutils: remove bitmap counting

All callers pass in valid number

Cleanup: rename getepsilon -> get_epsilon

Add asserts to check bvhutils args are correct

Would have prevented previous error going unnoticed.

Fix crash adding byte color grid images

Fix for fix, sorry for the noise

Code cleanup: simplify SVM stack assignment.

Code cleanup: remove some unused functions.