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: Jon W. <jw...@gm...> - 2014-05-27 16:20:42
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That's actually quite helpful! Thanks. Sincerely, Jon Watte -- "I find that the harder I work, the more luck I seem to have." -- Thomas Jefferson On Wed, May 21, 2014 at 12:53 PM, Graham Rhodes ARA/SED <gr...@ar...>wrote: > Components of the IntegrityWare SOLIDS++ commercial middleware may be > useful. For example: > > > > http://www.integrityware.com/meshlib.html > > > > Not sure how they handle interpolating vertex attributes, though. They > might support a user-provided function for that. > > > > Beyond that, we use Spatial’s ACIS library for some quite complex CSG > work. This adds another level of cost and complexity through, being > primarily used in the CAD industry. It does support non-manifold topology, > regularized and non-regularized solids, provides built-in functions to do > operations such as extruding or offsetting a sheet into a thickened solid, > geometry healing, etc. ACIS is extremely flexible in the way you can > attribute intermediate surfaces and edge lists that arise during the > evaluation of CSG ops. And there are the ACIS competitors…Parasolid, > Granite, Open Cascade (assuming these others still exist…my knowledge of > solid modeling kernels is slightly stale now). > > > > Graham > > > > *From:* Eric Haines [mailto:eri...@gm...] > *Sent:* Wednesday, May 21, 2014 11:39 AM > *To:* Game Development Algorithms > *Subject:* Re: [Algorithms] CSG operations on textured meshes -- > something better than CGAL? > > > > 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 > > > > > ------------------------------------------------------------------------------ > "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. Get started now for free." > http://p.sf.net/sfu/SauceLabs > _______________________________________________ > 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 > |
