On Mon, 3 Jan 2022 at 17:59, Stefan Brüns stefan.bruens@rwth-aachen.de wrote:
Seems my explanation was somewhat unclear ...
I do not want to remove the last vertex (p3), but the last segment. In the current code, vertex_type[3] (using your example) for p3->p0 is always marked as TYPE_LINE (see EndFigure code). In case of p0 == p3, this causes troubles in the intersection code. In case p0 != p3, the p3->p0 segment must be a line (for intersection tests and filling), regardless if END_OPEN or END_CLOSED. The only difference between OPEN or CLOSED is the stroking of the p3->p0 segment.
I think I see what you mean. You're right, we need the implicit segment for e.g. filling, so the current d2d_geometry_intersect_self() behaviour is correct in that regard.
What seems to work quite fine is setting the TYPE for the last vertex (vertex_type[3]) to either TYPE_LINE for non-coincident p3/p0, or TYPE_END (newly added type) otherwise. (TYPE_NONE is already overloaded and can't be used.)
For my current approach, see https://build.opensuse.org/package/view_file/ home:StefanBruens:branches:Emulators/wine/0003-d2d1-Skip-last-empty-segment- in-intersection-tests.patch?expand=1&rev=19
I think that approach should work, yes. Alternatives would be introducing a D2D_FIGURE_FLAG_ flag for this or just explicitly checking for coinciding start and end vertices in d2d_geometry_intersect_self(). Those alternatives have their advantages and disadvantages, but ultimately are largely equivalent. I don't have a clear favourite, so in that regard your (new) patch is fine. I would however request to please include a small test for the issue this fixes; both to demonstrate the issue and to prevent future regressions.
Henri