CompuServe Messages

>> Booleans in any program that I have used takes much trial and error to figure how they work, then they still don't work 100% of the time. I'm using Acad13, Designer, AutoSurf, and AutoVision I still have problems converting models that seem simple. Yes… to model, even things that don't need CAD accuracy, you need AutoCAD and Designer or, at the very least, r13. The problem comes in that even in r13's export to 3DS format, almost every mesh has 10% or more of the normals flipped around. I can understand how this would be a problem with DXF files, but why does this happen with r13's 3DS export function? I tried some models that were comprised of repeated blocks, and some of the blocks turned out OK, some did not. Hence, it was not a problem with the way ACAD had the faces turning. Why, then, did ACAD flip some of them around in the 3DS file? As for booleans, I still belive that the best answer is to have a function that can generate a solid CSG or BREP shape out of an object's faces and verticies. Some people have claimed this is impossible, but I've looked at the math required to do this – and it's not all that difficult. you jusst have to build in a lot of user-definable tolerances to make the majority of meshes solidify properly. If such a routine were written, almost all meshes that were a REASONABLY closed 3D surface could be solidified. The nice thing about this is you wouldn't always have to use it, but when booleans just won't work by the face method, you can have the option of having the program automatically generate a solid out of each of the two objects being operated on, perform the boolean flawlessly using 3D solid calculations, and export the resulting object back to 3DS as its native faces. one nice thing about this is the resulting object would be perfectly "clean" – i.e. no unwelded verticies, no coincident verticies, no duplicated faces. Such a routine could work well as an IPAS or built into 3DS. This is another one of those IPAS routines that if ssomeone wrote it, I'd buy it in a heart- beat. Indeed, I would susppose 1/4-1/2 of all 3DS users, if not more, would buy in in the first couple months in was out. Make you wonder why no one's ever done it, eh? <g>