[osg-users] GL_POINTS vs GL_LINES: same vertices displayed at different positions on screen

Chris 'Xenon' Hanson xenon at alphapixel.com
Fri Apr 8 20:17:38 PDT 2011

On 4/8/2011 1:22 PM, Louis Bouchard wrote:
> I have stumble on what seems to be a bug. It seems that when using the same coordinates for vertices with osg::PrimitiveSet::POINTS and osg::PrimitiveSet::LINES or LINE_LOOP, those vertices don't show up at the same place on the screen.  They are indeed displayed one pixel off.

  I think this is normal OpenGL rasterization. The points rasterize at the actual
location, but I think lines and polygon edges have some sort of not-at-the-point-or-edge
thing going that means they never rasterize ON one on of the two points that make up the
line. I can't find the reference to this right now, maybe someone else can give you the cite.

Chris 'Xenon' Hanson, omo sanza lettere. Xenon at AlphaPixel.com http://www.alphapixel.com/
  Digital Imaging. OpenGL. Scene Graphs. GIS. GPS. Training. Consulting. Contracting.
    "There is no Truth. There is only Perception. To Perceive is to Exist." - Xen

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