[fltk.general] filled non-convex polygon disappears when rotated

GitHub FLTK Project   FLTK News RSS Feed  
  FLTK Apps      FLTK Library      Forums      Links     Login 
 All Forums  |  Back to fltk.general  ]
Previous Message ]New Message | Reply ]Next Message ]

filled non-convex polygon disappears when rotated Paul Hahn 00:38 Oct 24 top right image
I have a weird problem that seems specific to using fl_begin/end_polygon() with fl_vertex() to draw a non-convex polygon (i.e., a filled "+" marker). With zero degrees rotation, the polygon appears. But application of a rotation angle not a multiple of 90 degrees results in nothing visible.

In contrast, when using fl_begin/end_loop() with fl_vertex() to draw the outline for the same polygon, the polygon (boundary) appears reliably, no matter what the rotation angle.

When I repeat the experiment with other kinds of (convex) filled and rotated polygons, there are no problems.

This is the first time I have tried to use fl_begin/end_polygon(). I am motivated by the need to do rotations on the filled polygon. I figure I am doing something wrong but I do not know what. I have tried to double-check that I do not have some kind of problems with the vertices -- seems OK.

I have attached a file to demonstrate the problem. If anyone is patient enough to check into this and help, I would really appreciate it.

You received this message because you are subscribed to the Google Groups "fltk.general" group.
To unsubscribe from this group and stop receiving emails from it, send an email to fltkgeneral+unsubscribe@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/fltkgeneral/6dcf9517-ccca-45da-b47b-8294d464837bo%40googlegroups.com.
Direct Link to Message ]
bottom left image   bottom right image
Previous Message ]New Message | Reply ]Next Message ]

Comments are owned by the poster. All other content is copyright 1998-2021 by Bill Spitzak and others. This project is hosted by The FLTK Team. Please report site problems to 'erco@seriss.com'.