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[Octave-bug-tracker] [bug #53023] Marker symbols not fully drawn for som


From: Rik
Subject: [Octave-bug-tracker] [bug #53023] Marker symbols not fully drawn for some output formats
Date: Tue, 30 Jan 2018 17:01:03 -0500 (EST)
User-agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0

Follow-up Comment #2, bug #53023 (project octave):

Why does it not show up on-screen?  Is there a different linecap or linejoin
being used for display versus printing?

>From gl-render.cc:


    case 'o':
        {
          int div = static_cast <int> (M_PI * sz / 4);
          if (! (div % 2))
            div += 1;               // ensure odd number for left/right
symmetry
          div = std::max (div, 5);  // ensure at least a few vertices are
drawn
          double ang_step = M_PI / div;

          glBegin (filled ? GL_POLYGON : GL_LINE_LOOP);
          for (double ang = 0; ang < 2*M_PI; ang += ang_step)
            glVertex2d (sz/2*cos (ang), sz/2*sin (ang));
          glEnd ();
        }


GL_LINE_LOOP is suppose to join the first and last vertex with a line segment.
 Is that not happening?  We could always use GL_LINE_STRIP and supply more
vertices than necessary so that OpenGL paints over an extra bit of screen.

I tried with filled markers, so that GL_POLYGON is used, and the results are
better.  There is still a small white indent, however, taken out of the
circle.


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