I am working on an OpenGL problem that I cannot figure out. I am drawing out a sphere composed of GL_QUAD_STRIP’s. I have the depth buffer enabled as well as face culling (with culling out the front faces). Then, a line using GL_LINE_STRIP is drawn on the surface of the sphere. All of this seems to work just fine. The funny thing is, when the sphere is rotated so that the line goes behind the sphere, I can still see bits of the line. Not the whole line, just pixels here and there. These artifacts diminish, and eventually disappear completely once the line get further and further past the limb of the sphere. Also, this only happens on Solaris, it does not occur on windows or Macs. Does anyone have a clue?
I think, the rasterizer in OpenGL is not guarenteed to generate exactly the same depth-values when generating the fragments between the same vertices when using different Geometry-Types. So what you are getting is z-fighting.
I don’t have a complete solution, but you could try to play around with depth-offset (I think thats the name of the extension, where you can bias the depth-values), etc.
Jan
That makes sense. I ran into something similar with polygon stiching. This was occuring with polygons, and it never occured to me the same thing could happen with lines. Thanks for the suggestion.