(06-06-2020, 03:25 PM)Irinikus Wrote: Procedures here, rather than primitives used in the likes of Maya!
Exactly ! That's the 'P' in parametric technology corp. Since the models are meant to be easily modified, yet still function the same way, you have to think ahead to decide how to create the model. PTC's biggest phrase they always beat into your head is "design intent."
Easy example, say you want to bolt a tube to a flat plate. Tube is 6" in diameter, plate is 6" wide. Put a series of holes through the tube, no problem. But the mating holes in the plate ... is the tube supposed to be lined up with the edge of the plate or centered in the middle of the plate ? What's the function ?
In this case it seems like it doesn't matter
but what about if there's a change order ?
If you want the tube to line up with the edge, then you run your holes 3" off the edge surface. But if the intent is that the tube is in the middle of the plate, you create a feature down the middle and align the holes with that.
Now change the width of the plate to 8". You better have chosen the method for making those holes that serves the function of the assembly, otherwise when you make changes, the thing is going to be all screwed up. "Hey ! Why is my tube an inch off center now ? "
That's both the strength and weakness of parametric modelling. IF you made the model correctly, according to how it is intended to be used, then it's super, you can change the model all over the place and it will regenerate to fit your new circumstance.
But if you made the model without understanding how it is supposed to work, you can change a dimension and the whole thing becomes garbage. You can lose entire sections of the model just by choosing the wrong feature to build off - everything is good until you make a required change then oops, that edge has disappeared into space, now there's nothing for the child features to use as a reference, it can't regenerate, you're up shoot creek, no paddle
Or in an assembly it works fine until you make a change, then uh-oh, now nothing fits together anymore, like it is supposed to.
That's why people either love it or hate it. You can't just model (well you can, but only for parts where you don't care about manufacturing), you have to think about what you want your model to do, before start to make it.
Some people don't like planning ahead