- Ensured proper closure of star and polygon shapes.
The start and end points now match - in cases with
degenerate bezier curves, the second-to-last point
is also aligned.
Proper shape closure is necessary for modifiers like
offset (future pucker bloat). If the start and end
points aren’t equal (within the comparison function’s
precision), the shape will be closed with a straight
line - and during offsetting, that line will become
visible, even though it’s not intended.
- Use of the internal _zero() function for point equality check
in modifiers algs led to incorrect results when p2.x or p2.y
was zero (division by zero).
The intent was to treat nearly identical points as equal, but
this approach was flawed - at the modifier stage, it’s no longer
possible to tell if small gaps are intentional or just due to
limited numerical precision (as seen for example in the difference
between the start and end points of star/polygon shapes).
One point was skipped during the creation of the offset
corner. The error was not visible because the point lies
on the line, but it will become apparent if further
modifiers are applied to the object (not supported now).
According to tests in AE, the offset direction should
not depend on the direction of the shape. A positive
offset value expands the shape, while a negative value
contracts it. Fixed.
For long Bezier curves compared to the offset value,
the offsetting algorithm caused deformation. The problem
became evident after adding mask extension, as the simple
shapes defined there are based on Bezier curves rather
than as shapes like a circle/rect/etc, which is the case
for the offset. Now fixed.
Due to the lack of an analytical solution for Bezier
curves offsetting, a simple and computationally cheap
approximation has been implemented. The algorithm shifts
the segments connecting control points and determines
new points based on their intersections.
@issue: https://github.com/thorvg/thorvg/issues/2230
