Re: [osg-users] Stitching together sphere geometry in OpenSceneGraph
Thanks, setting the texture's wrap mode to CLAMP_TO_EDGE worked perfectly! Regards, Preet On Thu, Mar 1, 2012 at 10:45 PM, Jean-Sébastien Guay jean_...@videotron.ca wrote: Hello Preet, * The issue I've run into involves where my 2D texture wraps around and meets itself on the sphere: http://i.imgur.com/ftVH2.png I don't think there's anything wrong with your geometry and texcoords. Good work! The problem looks like you may be using the default texture wrap mode, which is CLAMP. This mode can also be called clamp to border, which when texture coordinates run outside the range of 0-1 will give a border color, which defaults to black. The problem is that when the texture coordinates are exactly 0 or 1, when you have linear interpolation enabled as filter mode (again the default), then the border color will still get sampled (since it's trying to filter using that texel and the one next to it, which is outside the 0-1 range). So you get those black lines around your textures. Try to specify the CLAMP_TO_EDGE wrap mode instead. This will simply sample the same texel at the border and should eliminate the black line. Hope this helps, J-S -- __ Jean-Sebastien Guay jean_...@videotron.ca http://whitestar02.dyndns-web.com/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] Stitching together sphere geometry in OpenSceneGraph
Hey all, I'm trying to draw a simple sphere (yes, I know there's a drawable type available) to learn how to build up simple geometry, by specifying vertices, normals, texture coordinates and indices. I eventually want to create a function that will give me vertices for spheroids that aren't perfect spheres, but follow the same principles. I've been doing okay so far, and used a spherical coordinate transform to get cartesian coordinates. I have vertices, normals, texture coordinates and indices. * The issue I've run into involves where my 2D texture wraps around and meets itself on the sphere: http://i.imgur.com/ftVH2.png Like shown in the picture, there's a visible seam there. There are also shadows where multiple identical vertices are present at the poles. I'd like to know how to get rid of the seam and shadows! I am manually mapping the texture using the simplest 2d texture-sphere, shown here: http://paulbourke.net/texture_colour/texturemap/texture.gif If I use the bare minimum vertices (no duplicates) to define the sphere then the seaming and shadows disappear but I'm unable have the 2D texture wrap all the way around, and see extreme warping at the poles (which makes sense): http://i.stack.imgur.com/l9baA.png Regards, Preet ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Stitching together sphere geometry in OpenSceneGraph
Hello Preet, * The issue I've run into involves where my 2D texture wraps around and meets itself on the sphere: http://i.imgur.com/ftVH2.png I don't think there's anything wrong with your geometry and texcoords. Good work! The problem looks like you may be using the default texture wrap mode, which is CLAMP. This mode can also be called clamp to border, which when texture coordinates run outside the range of 0-1 will give a border color, which defaults to black. The problem is that when the texture coordinates are exactly 0 or 1, when you have linear interpolation enabled as filter mode (again the default), then the border color will still get sampled (since it's trying to filter using that texel and the one next to it, which is outside the 0-1 range). So you get those black lines around your textures. Try to specify the CLAMP_TO_EDGE wrap mode instead. This will simply sample the same texel at the border and should eliminate the black line. Hope this helps, J-S -- __ Jean-Sebastien Guay jean_...@videotron.ca http://whitestar02.dyndns-web.com/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
