There is an adjustment pass in bevel that tries to make the bevel
widths at either end of a beveled edge as equal as possible.
When there are hundreds of beveled edges end-to-end, these adjustments
can accumulate out of control and result looks awful.
Yet the adjustment pass is sometimes needed to avoid equally awful
appearances in other cases (see the "Bent test" in the bevel regression
tests).
This change uses the 'Clamp overlap' flag of bevel (on by default in
the modifier, not in the tool) to limit the amount of adjustment to within
10% of the desired width. When the flag is off, there is no limit to the
adjustment.
When one edge is beveled at a vertex among more than 1 other unbeveled
edges, the code makes a polygon around the vertex. The position of the
vertices on the non-adjacent-to-beveled-edge edges depended on the
ordering of edges, which leads to inconsistent-looking results in seeming
symmetrical situations. Changed to use the bevel amount as slide
distance, which fixes this.
Two problems fixed. One, the comparison of angles to
'almost straight' or 'almost zero' needed a bigger epsilon.
Two, using the corner normal instead of the average face normal
is usually the right thing to do, and what the code was doing,
but in some cases the corner normal could be very wrong.
Fairly large changes to bevel code to do a better job
of keeping UVs from crossing islands, etc.
Updated http://wiki.blender.org/index.php/Dev:2.5/Source/Modeling/Bevel
to explain algorithm used for maintaining UVs.
Updated the bevel_regression.blend tests in lib tests.
Current behavior of bevel is to 'loop slide' along unbeveled edges
when possible, but this produces uneven bevel widths sometimes,
so this option lets user choose between having the loop slide effect
or having more even bevel widths. Trying it out with default being
'no loop slide', so different from current behavior. May reverse this
choice later, depending on user reactions.
For areas that require append, store the last node,
Previous behavior would too easily hide poorly performing code.
Also avoid (prepend, reverse) where possible.
Made the test for whether one can "see" an adjacent edge less
knife-close to 180. This means it will chose to slide along
such an edge less often, and avoid some spikes.
Add slider to adjust the influence of weights relative to geometry distortion.
This allows subtle influences to be applied - without drastic changes in behavior.
Also, changed the algorithm for generating the vertex meshes when not all
edges into a vertex are beveled. Now it tries to slide along edges that
form part of the silhouette when possible; when not possible, it tries
to snap to the best plane in between the beveled edges.
Previously decimate on flat areas of a mesh would more or less randomly collapse edges.
(giving bad topology).
This commit includes a topology 'cost', so smaller edges on flat surfaces collapse first.
When the multisegment profile joins two unbeveled edges, all in the same
plane, users desire that rather than the current behavior of linear
interpolation between those edges, the profile should curve.
This changes behavior to do that. The old behavior can be obtained
by setting the profile parameter to 0.25, if desired.
`CustomData_bmesh_interp_n` was expecting the 'dest' arg not to have its offset applied.
This was a bit confusing since the source args have it applied,
and in some cases we only have the destination with the offset.
