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.
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.
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.
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.
Now the bevel tool, modifier, and internal operator have a material
slot # parameter that the user can set. If left at default of -1,
behavior is as current -- bevel face material is taken from the
closest original face (this may be ambiguous). If material slot
is >= 0, it gives the material slot index number for the material
to use.
If the side of a beveled edge hit another vertex, the offset
amount reset to zero. This was the result of commit rB1582dd5e4d7c
which clamped the amount to zero to avoid creating spikes with
obtuse angles. Now we clamp the amount to the closest end of
the edge to where the amount wants to be.
Also fixes the first part of T40365.
With very small meshes or very small bevel amounts, the bevel
profile would be flat even if a round one was requested.
Problem was that the code was checking the length of a cross
product for closeness to zero to test coplanarity. Needed
to normalize things before making that test to account for scale.
When doing a 'weld' type join where there are two non-beveled edges
in the same plane one beveled one but not the other, then there
should be a curved profile; bug was creating a straight one.
Used a different technique to resolve "impossible" offset cases
that makes more consistency. Also changed the plane in which
the profile lies for the case with only one beveled edge and
more than 3 other edges.
When rebuilding the polygons that touch bevel-involved vertices,
need to copy the edge attributes from corresponding original edges.
Special treatment of corner segments, to maintain continuity of
smooth and seam attributes.
Another fix: if have four meeting edges, two opposite ones beveled
and the other two not, propgate the non-beveled-edges attributes
across the line that joins them (perpendicular to the bevel).
This updates the fix in rB27db75363, which had to be undone
because it broke other bevels.
It also fixes cases where edges went away went doing vertex
bevel on vertices with some wire edges.
The test for wire edges when reattaching was wrong, because
some newly made edges are wire at the point of the test.
This made some duplicate edges.
Need to track the original wire edges a different way.
Now code explicity excludes wire edges from beveling
and reattaches the wire edges to one of the newly
created vertices after beveling.
Also fixes a bug where vertex-beveling a wire-edge-only
vertex would not reattach the wire edges.
