On Montag, 3. Januar 2022 16:40:50 CET you wrote:
On Mon, 3 Jan 2022 at 15:10, Stefan Brüns stefan.bruens@rwth-aachen.de
wrote:
On Montag, 3. Januar 2022 12:58:50 CET you wrote:
On Fri, 31 Dec 2021 at 08:23, Stefan Brüns stefan.bruens@rwth-aachen.de
wrote:
When the last vertex is coincident with the first vertex, the last segment should be suppressed for both END_OPEN and END_CLOSED.
When the last, zero length segment is not omitted d2d_geometry_intersect_self will add invalid segments.
Unfortunately, I don't think that's correct. For an END_OPEN figure, the first and last vertex coinciding doesn't imply that the last segment is a zero-length segment.
Please supply an example where coinciding does not mean zero length.
Last vertex refers to the second vertex of the last segment, not its start vertex.
Consider for example a triangle like this:
p0, p3 /\ / \ /____\p1 p2
and the corresponding Direct2D calls:
BeginFigure(p0, ...); AddLine(p1); AddLine(p2); AddLine(p3); EndFigure(END_OPEN/END_CLOSED);In the END_CLOSED case, we'd first create three segments:
p0->p1 p1->p2 p2->p3and then we'd have a fourth implicit zero-length segment p3->p0. By removing the p3 vertex, we replace the p2->p3 and p3->p0 segments with an implicit p2->p0 segment.
In the END_OPEN case however, we just have the three explicit segments above, without the implicit p3->p0 segment. In that case, removing the p3 vertex simply removes the p2->p3 segment, and we'd be left with the following figure:
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.
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
Regards, Stefan