[Octave-bug-tracker] [bug #40247] patch chooses wrong vertex for coloring face

[Rik]

URL:
  <http://savannah.gnu.org/bugs/?40247>

                 Summary: patch chooses wrong vertex for coloring face
                 Project: GNU Octave
            Submitted by: rik5
            Submitted on: Fri 11 Oct 2013 11:02:09 AM PDT
                Category: Plotting with OpenGL
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Any

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Details:

According to the documentation, with "facecolor" = "flat", the patch color is
taken from the first vertex specified in the "faces" property.  Octave is
using some other algorithm.  Likely fix will be in gl-render.cc.

The following example should produce a red face.


v  = [0 0 0;1 0 0;1 1 0;0 1 0];
f = [1 2 3 4];
fvc = [1 0 0;0 1 0;1 0 1;1 1 0];
h = patch ("Vertices",v,"Faces",f,"FaceVertexCData",fvc,
           "FaceColor","flat","EdgeColor","flat",
           "Marker","o","MarkerFaceColor","flat")


Specifying a different first vertex, should change the color.  So, 


set (h, "faces", [4 3 2 1])


should color the face yellow because the 4th vertex (which is listed first and
thus sets the color) facevertexcdata value is [1 1 0].






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