[osg-users] Strips on AnimatedTexturing on Terrain by GLSL
Hi All, I had created animated texturing on terrain with using shaders but I have already realized some artifacts on the terrain as you see from that VIDEOhttp://www.fileden.com/files/2007/9/10/1423182/AnimetedTexturing.wmv. Why have this strips created on the terrain in each loop? Any advices to get rid of them ? Note : In vertex shader I only iterate the caustics texture x coordinate by the way, causticsCoords = gl_MultiTexCoord0.xy;; causticsCoords.x = fract( causticsCoords.x + float( timeValue * causticsSpeed ) ); All of the important pattern about animating texture on terrain is preceeded dodes. Best Regards. Umit Uzun ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Strips on AnimatedTexturing on Terrain by GLSL
Umit, It's a well known gotcha with texture repeats. Each vertex has increasing causticsCoord.x. Imagine the vertices with coord 0.0, 0.1, 0.2, 0.3 etc. The fragments in between any of these coords have _interpolated_ texcoords i.e. a fragment halfway betwen 0.0 and 0.1 vertex has a texcoord of 0.05. For the end vertices, you have 0.8,0.9,1.0, 1.1. The fract function turns this into 0.8, 0.9, 0.0, 0.1 Hence a fragment half way between 0.9 and 1.0 interpolates the texcoord between 0.9 and 0.0, giving 0.45, not 0.95 as you would want. Between 0.9 and 1.0, then the actual texcoord used decreases rapidly from 0.9 to 0.0. The artifact you see is all of your caustics texture, mirrored, and shoved into the last vertex gap. To get rid if it, try losing the fract instruction. There may also be dependencies on your texture mode (REPEAT, MIRROR, CLAMP) that you might need to play with depending on what your texture looks like. Hope that helps, David ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Strips on AnimatedTexturing on Terrain by GLSL
Hi David, I unattached the fract math function and all strips gone away :) I haven't thought it was a simple bug :) Thanks so much. Best regards. Umit Uzun 2008/10/17 David Spilling [EMAIL PROTECTED] Umit, It's a well known gotcha with texture repeats. Each vertex has increasing causticsCoord.x. Imagine the vertices with coord 0.0, 0.1, 0.2, 0.3 etc. The fragments in between any of these coords have _interpolated_ texcoords i.e. a fragment halfway betwen 0.0 and 0.1 vertex has a texcoord of 0.05. For the end vertices, you have 0.8,0.9,1.0, 1.1. The fract function turns this into 0.8, 0.9, 0.0, 0.1 Hence a fragment half way between 0.9 and 1.0 interpolates the texcoord between 0.9 and 0.0, giving 0.45, not 0.95 as you would want. Between 0.9 and 1.0, then the actual texcoord used decreases rapidly from 0.9 to 0.0. The artifact you see is all of your caustics texture, mirrored, and shoved into the last vertex gap. To get rid if it, try losing the fract instruction. There may also be dependencies on your texture mode (REPEAT, MIRROR, CLAMP) that you might need to play with depending on what your texture looks like. Hope that helps, David ___ 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
