8 Replies Latest reply on Jan 29, 2009 4:33 PM by Matt McKendrick

    Spline-on-Surface and Converted/Offset Entities gripes

      Why is the on edge relation removed when a converted entity is trimmed? If it is possible to have multiple sections of converted entities on one edge chained end to end, (even if in multiple sketches) then the relation should not be removed when trimmed. Furthermore, when I drag the endpoints to create multiple sections, it adds relations to the endpoint, fully defining it. I'm sorry, but if an entity lies on another entity, then the endpoint is already coincident AND UNDERDEFINED. Since when is a point that is already constrained to lie on an edge fully defined when that relation is duplicated? It makes no sense whatsoever!

      Why are offset splines able to be trimmed sometimes, and other times I get the error that offset splines cannot be trimmed"? Clearly they can, so what gives?

      Why does making one endpoint tangent to another curve (but not end-to-end) over-define my sketch OR move the point to an undesired location and then fully define the point? If all it contains is a tangent and a coincident relation, I sould be able to move the point along the entity it is coincedent and tangent to, but I can't.

      And, since these are all graphics related...Why is SW still offering 169.xx series drivers when nvidia is on 181.xx? The vistax64 driver for a QFX5600 offered on the SW driver section suffered from banding, choppy rotation, and zooming with the mouse wheel was so slow I found it unusable, even if running a windows classic theme.

      And why-oh-why are surface splines so impossible to control? If I can project a curve onto a surface, I should be able to draw a similar spline on the surface, but this is not possible. It is always overdefining, creating invalid geometry, blowing points WAY outside (like 100 meters away on a .25 meter part) the graphics area, or simply not responding whatsoever to my input, but undo will undo the null response... Also, I have noticed that moving CV's on a surface spline does not alter the point's tangency handle, it only moves the point. This is inconsistient with how splines are treated elsewhere in SW, and further cripples the use of this tool. If anyone can tell me how they have used surface splines with any effect, I'm all ears. Otherwise, I'm calling a spade a spade. Offer a tool that works or fix it.

      One more thing...How do I measure the length of a spline? If this isn't possible, it should be. The return of the curvature curve would be appreciated as well, while you're in there .

      My last comment would be that it is Friday and Y'all have a good weekend!
        • Spline-on-Surface and Converted/Offset Entities gripes
          Matt Lombard
          Yeah, welcome to the world of splines.

          Trimmed entities? Use "split entities" and convert one side of the curve to construction, or use the thing you're calling a bug later - drag the endpoint of a converted entity back to shorten the spline.

          I went through the whole argument that if you can drag an endpoint of a converted spline then it never really was defined to start with. You're right that it doesn't make sense, but it's a whole lot easier to use as is, if you can just deal with the quirk.

          Offset/trimmed splines? Blech. The one thing I tell people is that you've got to know 5 ways to do stuff in SW surfacing because the first 4 may not work.

          Sketch relations (and assembly mates), particularly spline sketch relations, are FAR below the functionality of the rest of the software. I believe SW uses DCubed (from Siemens/UGS) for constraint solving. No good news here because there is no accountability. This discussion will always end in finger pointing until someone at SW decides to do something.

          Graphics. Geez. How many unanswered questions are there around graphics? How about OpenGL vs DirectX? SW will never open up about what goes on here in a way that regular users can understand I suspect because there are some business deals in the background that are what really drive this, rather than the interests of the user. The only way you can make your voice heard in this respect is to go buy Inventor or Alibre, which use DirectX instead of forcing users into expensive OGL cards. Read this to find out more: http://dezignstuff.com/blog/?p=367

          When I use other software that deals with splines, I'm surprised at how matter-of-fact splines can be. They don't have to act funny, or lose endpoints, overdefine relations, kink or flip. They just work with no fanfare.

          You can measure a spline, but you can't dimension it, or drive the length. If you just click on the spline, then look in the lower right on the status bar, it lists the length as "arc length".

          In the end, SolidWorks is good at some stuff in the CAD world, and not so good at other stuff. Splines are part of that "other stuff". If you use mostly splines and surfaces, you may be better off looking at a different tool.
            • Spline-on-Surface and Converted/Offset Entities gripes
              The dragging endpoint issue is that after one drag, it gains a duplicated relation that fully defines the point. Yes, I can deal with it. Yes, it is still a bug and should be fixed so that I don't have to.

              I for one do not subscribe to the "you get what you pay for" analysis of SW splines. We have all paid alot and gotten very little with respect to splines.

              If you, Matt, are suprised by how matter-of-fact splines can be in other software, why are you so quick to disregard their shortcomings in the end? Will we ever get SW to improve if we all resign to the idea that SW has issues, and we should all either accept them or take a hike (to other software, of course)? I am not saying this is your attitude, but you aren't exactly providing constructive suggestions to the contrary.
                • Spline-on-Surface and Converted/Offset Entities gripes
                  Matt Lombard

                  Will Smith wrote:

                   

                  If you, Matt, are suprised by how matter-of-fact splines can be in other software, why are you so quick to disregard their shortcomings in the end? Will we ever get SW to improve if we all resign to the idea that SW has issues, and we should all either accept them or take a hike (to other software, of course)? I am not saying this is your attitude, but you aren't exactly providing constructive suggestions to the contrary.

                  To be honest, I've been at the front of or in the middle of a lot of efforts to try to get various improvements in SolidWorks. Everything from the obvious to the esoteric. At BEST, the road to improvement is long and slow. A "successful" effort yields change 2 years down the road. The average effort lands you exactly nowhere. If you become "the boy who cried wolf" through too many efforts with no results, you will never achieve anything. So its easy to get jaded if you expect somebody to do something.

                  Ok, here's my thing about offset/trimmed splines. There is almost always a way to get where you want to go if you're willing to use additional sketches to create the stuff you need. At worst you will have to remove the "on edge" or offset relation. Yes, I know that kills the associativity, but at least it works. Use the split entities points instead of trimming.

                  Spline on surface is a temperamental beast. One thing to keep in mind is to only cross an edge if the edge is at least tangent. Also, if I want the endpoint of a SOS to be on an edge, I always draw it on the surface, then move it to the edge. I've seen endpoints actually detach from the spline itself too many times.




              • Spline-on-Surface and Converted/Offset Entities gripes
                Mark Matthews

                Will Smith wrote:

                 

                Also, I have noticed that moving CV's on a surface spline does not alter the point's tangency handle, it only moves the point. This is inconsistient with how splines are treated elsewhere in SW, and further cripples the use of this tool. If anyone can tell me how they have used surface splines with any effect, I'm all ears. Otherwise, I'm calling a spade a spade. Offer a tool that works or fix it.

                Yes curve on surface splines are difficult to control, and they do not act like splines in free space or on a sketch plane precisely because they are in the surface space, which is a different animal (u,v surface topology as opposed to x,y,z 3-D). A projected curve is alot more complex a spline than one you can draw directly on the surface, so it's almost impossible to recreate one this way. I almost never draw a curve on surface cause of the over-constraining that happens with the buggy solvers SW uses. Pro-E handles them much better, but they too do not behave predictably as you manipulate the CV's.
                  • Spline-on-Surface and Converted/Offset Entities gripes
                    Matt McKendrick
                    Not making excuses or apologizing for Solidworks, but I have resigned myself to the fact that splines suck, and are difficult to work with, and impossible in some cases. In the case of an offset spline, I will usually manually convert it to arcs so I can trim, extend, etc. I know this is a lame work-around, but I don't want to burn time trying to fight that lost cause anymore. That being said, I have hopes SW will eventually have this area improved, but I am not holding my breath.
                  • Spline-on-Surface and Converted/Offset Entities gripes
                    Charles Culp
                    In response to Matt McKendrick,

                    In my opinion splines are great. After many years of using splines in graphics design programs (which is what they all use, Adobe Illustrator, Macromedia Freehand, and all the publishing tools), I think some of the more recent changes (2007, 2008) to splines have made them much more controllable.

                    The only thing I'm still not satisfied with his how tangencies are controlled at control points. In my opinion, the easiest program to control splines with was Macromedia Freehand. You could move each tangency control, and it would effect both sides. CTRL-click, and it would only effect one side at a time.