I'm testing constraints with an extrusion along a path to create a door frame. I want to constrain the height and width and have them as variables but when I attempt to 'flex' the variables the results are inconsistent and wrong. I've created the constraints by constraining the path before extruding as I can't see a way to do it afterwards. The height constraint seems to work but the width is giving odd results. Example attachedperforatorNamedViewtest.dgn
Hi Duncan,
i had a very quick look at the file and the unexpected behaviours you are seeing when changing variables' values is due to the profile not being well constrained. you should always try to draw your profiles as closed shapes and check their DOF (degrees of freedom) is 0/. This means that there is only one possible solution for any change of the parameters. This somethimes may be tricky when the profile is complex it is worth getting used to do so.
I have attached a quick edit of your file, let me know if you need more help with this!
5123.perforatorNamedViewtest.dgn
Thanks for the prompt response Marco. i'm still having problems with this file (your amended version). I changed the width value to 2 metres and the frame does not respond properly. It just changes so some weird thing. I understand the need to set proper constraints but I would have thought that if I constrained the path for an extrusion and the modified the value the extruded geometry should follow?
mmm...I might have misunderstood then. There was something odd with the extrusion profile: I couldn't isolate or select it or check/show its constraints, so i have re-created it, constrained it and replaced it as an input element for the extrusion along (I have shifted the feature inadvertedly, please move it back where it is supposed to be )...let me know if it is any better now.
perforatorNamedViewtest_Test_Marco.dgn
That seems to work as expected. I created the extrusion using the Extrude along tool in the solids tab using a simple smartline path so I don't know what I could have done to upset it. I'm a little concerned that this is a bit to easy to break at the moment.
I understand Duncan. The guidline when creating any parametric geometry is to have the 2D elements well constrained. All profiles to be extruded should be single line strings or shapes whenever possible as they are much easier to constrain. The need to have profiles well constrained is becasue the solver cannot know which solution to pick when there are multiple ones avialble as they will all be mathematically correct (this is were geometrical and dimensional constraint tell the solver which solution is right).
Once the geometry and the solids are generated following the above guideline, they shouldn't break. So far 99% of the issues reported for geometry not responding to parameters changes as expected was due to underconstrained models. We are going to improve the constraint tools to make them easier to use and any specific feedback is welcome!
Thanks Marco. I think the most helpful things are documented workflows. A door would be a good architectural example with Height width, door leaf thickness etc. In Revit I have a specific workflow ie create reference planes, lock geometry to ref planes and flex. Having an equivalent in Microstation would be helpful. I know there are some videos on this but more is needed in my opinion.