Re: [osg-users] intersection of lines: line widths?
Hi Andy, Am 22.10.2012 21:05, schrieb Andy Skinner: I know that intersections are about 3d world coordinates, and line widths are about pixels. But is there a way to use line widths in calculating intersections with the polytope intersector? There is currently no code in PolytopeIntersector which takes line widths (or point sizes) into account. While it would be possible to implement it I doubt that it would be worth the effort. In other words, I want a wider line to be easier to pick. I think this could be accomplished by a post-processing step on the results: Normally you would use the nearest intersection but in your case you could also check the line width and prefer thicker lines over nearer lines. I could just expand the polytope a bit, except that the lines are just one kind of thing in the scene, and they could have different line widths. I think your expanded polytope-idea should also work. You could use differently sized polytopes for different line widths. As for your other kinds of thinks in the scene you should be aware that the performance of PolytopeIntersector for 2d-geometries is rather bad. It is much faster to use LineSegementIntersector for those and combine the results afterwards. thanks, andy Cheers, Peter ___ 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
Re: [osg-users] intersection of lines: line widths?
Thanks for comments, Peter. By easier to pick, I didn't mean relative to other lines in the scene, but that I wouldn't have to be as close to the actual line geometry. It is a question of whether the line will be in the list of intersections, rather than which intersection I choose. I suspect the same thing about whether it is worth the effort. As for your other kinds of thinks in the scene you should be aware that the performance of PolytopeIntersector for 2d-geometries is rather bad. It is much faster to use LineSegementIntersector for those and combine the results afterwards. By 2d-geometries, do you mean triangles and quads (and not 2D scenes)? And that it would be better to run the polytope intersector for points and lines, and a separate line intersector for triangles and quads, and combine intersections? I know all of that is pretty much what you said, but I wanted to be sure. That's using two intersection traversals. Sounds interesting if it is really faster. thanks, andy ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] intersection of lines: line widths?
Hi Andy, Am 23.10.2012 15:03, schrieb Andy Skinner: Thanks for comments, Peter. By easier to pick, I didn't mean relative to other lines in the scene, but that I wouldn't have to be as close to the actual line geometry. It is a question of whether the line will be in the list of intersections, rather than which intersection I choose. I suspect the same thing about whether it is worth the effort. As for your other kinds of thinks in the scene you should be aware that the performance of PolytopeIntersector for 2d-geometries is rather bad. It is much faster to use LineSegementIntersector for those and combine the results afterwards. By 2d-geometries, do you mean triangles and quads (and not 2D scenes)? And that it would be better to run the polytope intersector for points and lines, and a separate line intersector for triangles and quads, and combine intersections? I know all of that is pretty much what you said, but I wanted to be sure. That's using two intersection traversals. Sounds interesting if it is really faster. Yes, I did mean triangles and quads. I haven't done performance measurements but I did implement the PolytopeIntersector for triangles and quads. There are quite a few cases to cover to get it correct. The IntersectionVisitor has the additional advantage that it can use a kd-tree for speedup (which unfortunately is totally geared towards triangles, and hence unsuitable for the PolytopeIntersector). But, yes, I do mean performing two separate intersections, where you can turn off the PolytopeIntersector checks for 2d-elements by using setDimensionMask(DimZero|DimOne) and merging those results with the results from a LineSegmentIntersector. thanks, andy Cheers, Peter ___ 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] intersection of lines: line widths?
I know that intersections are about 3d world coordinates, and line widths are about pixels. But is there a way to use line widths in calculating intersections with the polytope intersector? In other words, I want a wider line to be easier to pick. I could just expand the polytope a bit, except that the lines are just one kind of thing in the scene, and they could have different line widths. thanks, andy ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
