Re: [Algorithms] CSG operations on textured meshes -- something better than CGAL?
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Re: [Algorithms] CSG operations on textured meshes -- something better than CGAL?
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From: Eric H. <eri...@gm...> - 2014-05-21 15:38:53
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I'd certainly like to know, too. MeshLab might have one hiding in its bowels, but I haven't looked hard enough yet. MeshMixer looks super-cool, but appears to be just an application, not a library. On Wed, May 21, 2014 at 11:05 AM, Jon Watte <jw...@gm...> wrote: > > You are going to be distorting triangles in different ways depending on > the overall shape of the mesh at any given point though. > > If you just retain existing UV coordinates for the new vertices, the > results will be... strange. > > I do this operation with some frequency in 3ds Max, and it works the way I > expect there. > > The 3ds Max boolean (and proboolean) modifier behavior would be good > enough for my purposes, although they do have some edge cases and > limitaitons (a k a "bugs" :-) > But I don't want to buy a copy of 3ds Max per server that will be running > this code, not to mention I want to run the servers on Linux. > > So, does anyone know of any textured-triangle-mesh CSG library out there, > free or paid for, that would work? > > Sincerely, > > jw > > > > > > > Sincerely, > > Jon Watte > > > -- > "I find that the harder I work, the more luck I seem to have." -- Thomas > Jefferson > > > On Tue, May 13, 2014 at 10:07 PM, James Robertson <ja...@os...>wrote: > >> You are going to be distorting triangles in different ways depending on >> the overall shape of the mesh at any given point though. If you just >> retain existing UV coordinates for the new vertices, the results will >> be... strange. >> >> Consider the case where a convex region meets a concave one. One side of >> the triangle will be slightly expanded, while the other side will be >> contracted. Of course you know your input data better than us, so maybe >> such distortions are acceptable or won't be noticeable, but they will be >> there. >> >> >> >> On 14/05/2014 01:41, Jon Watte wrote: >> >> I don’t believe you will be able to use your existing uv values with >>> the mesh that results from this csg operation >> >> >> The operations I want to do are rigid and well conditioned and do not >> stretch or generate new surfaces compared to the input meshes. They may >> invert the winding of triangles, though (so normal maps would have to be >> flipped) in the case of a cut-out. >> I also need to preserve vertex bone weighting, too... something that can >> preserve UV should be able to preserve that, too. Worst case, I put in a >> vertex ID value in the UV channel and loop up the other parameters based on >> that. >> >> So... no general purpose parameterized trimesh CSG library available? >> >> Sincerely, >> >> jw >> >> >> >> >> >> Sincerely, >> >> Jon Watte >> >> >> -- >> "I find that the harder I work, the more luck I seem to have." -- Thomas >> Jefferson >> >> >> On Thu, May 8, 2014 at 12:28 PM, Chris Green <cg...@va...>wrote: >> >>> I don’t believe you will be able to use your existing uv values with >>> the mesh that results from this csg operation – it has a different >>> topology, and there will be changes in the ratios of the areas of different >>> parts of the model, with really bumpy areas of the mesh being smoothed out, >>> etc. You’ll even have brand new areas emerge that don’t have corresponding >>> areas on the original model, as holes are filled in, etc. >>> >>> >>> >>> What might work better is to just do the csg operation and generate a uv >>> atlas for the resultant mesh. You can then generate a new texture map for >>> this uv parametization by sampling from the original one, in a similar >>> manner to the way in which people produce bumpmaps mapping the normals of >>> highly tessellated models onto low-detail models. >>> >>> >>> >>> >>> >>> >>> >>> *From:* Jon Watte [mailto:jw...@gm...] >>> *Sent:* Thursday, May 08, 2014 11:08 AM >>> *To:* Game Development Algorithms >>> *Subject:* [Algorithms] CSG operations on textured meshes -- something >>> better than CGAL? >>> >>> >>> >>> I have a triangle mesh composed of many submeshes with different >>> textures/materials. This mesh may not be a 2-manifold -- it may have open >>> edges. Typical game art. >>> >>> >>> >>> I now want to create a 3mm thick shell of this mesh. As an >>> approximation, taking each triangle, and extrude it back along the normal >>> of each vertex, and union all of those generated chopped pyramids would be >>> an approximation of what I want. If I do literally that, and self-union the >>> result, then that should resolve the self-intersection problems I'll run >>> into along narrow sharp creases etc. >>> >>> >>> >>> I can't find any library to do this, though. CGAL has some fairly robust >>> functions on NEF polyhedra, but those polyhedra don't seem to allow >>> parameterization (which is academic speak for texture coordinates that may >>> have discontinuities across edges.) >>> >>> >>> >>> So, what are some robust CSG libraries available that work on such >>> game-style meshes, preserving texture coordinates? >>> >>> >>> >>> (And actually, I don't have one such mesh; I have > 120 million such >>> meshes, so a by-hand or even script-the-Max-shell-modifier solution is >>> unlikely to work. I do have hundreds of Linux servers at my disposal, >>> though.) >>> >>> >>> >>> Sincerely, >>> >>> Jon Watte >>> >>> >>> -- >>> "I find that the harder I work, the more luck I seem to have." -- >>> Thomas Jefferson >>> >>> >>> ------------------------------------------------------------------------------ >>> Is your legacy SCM system holding you back? Join Perforce May 7 to find >>> out: >>> • 3 signs your SCM is hindering your productivity >>> • Requirements for releasing software faster >>> • Expert tips and advice for migrating your SCM now >>> http://p.sf.net/sfu/perforce >>> _______________________________________________ >>> GDAlgorithms-list mailing list >>> GDA...@li... >>> https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list >>> Archives: >>> http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithms-list >>> >> >> >> >> ------------------------------------------------------------------------------ >> "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE >> Instantly run your Selenium tests across 300+ browser/OS combos. >> Get unparalleled scalability from the best Selenium testing platform available >> Simple to use. Nothing to install. 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