The difference between actions and objects, i.e. commands and results. The history is just a list of commands. While it is certainly possible to delete individual history commands from the history panel, I think you are mostly talking about deleting a sketch “the regular way”, i.e. direct modeling.
Even when that happens, the actual history steps are still there — they just can no longer be completed and will show the missing reference error. So if you delete a sketch, any associated bodies will disappear from the drawing — BUT all the history steps are still there. They just can’t be completed. For example, you can no longer extrude a body without a sketch. Or align a body to a sketch that is no longer there.
Believe it or not, this is not caused by the history feature. This is the way direct modeling has always worked — except now sketches can also be direct modeled. Every action you take is applied to the current state of the drawing — which is always the sum total of all your actions so far, again, including any actions taken on sketches.
Say you extrude a cylinder and proceed to modify it with holes, chamfers, etc. Now, if you delete the cylinder, everything you did to it will disappear. Again, Shapr3D has always worked this way except sketches were second class citizens. You could always modify any bodies — which would also affect any associated bodies or features. And it seems completely normal because that is the way direct modeling works. And now sketches work the same way.
Once again, this is completely independent of the HBPM feature. It is just “all direct modeling — all the time”. Which (IMHO) is the best way to wrap your head around it. As always, what you see in front of you is what you have to work with at any given point in time. You can hide objects, etc. but you can only add to or modify the current drawing state.
In essence, the thing that some people are complaining about is in reality just more of what most people like the best about Shapr — more direct modeling. Granted, it has been a huge workflow adjustment for some people, but conceptually at least, it is just more of a good thing.
HBPM is an additional (and for all practical purposes) completely separate and optional feature. As always, you can do almost anything you can imagine with direct modeling, but sometimes the ability to adjust history steps can save a lot of tedious repetition. The classic example being adjusting a “master body” before making copies — thus avoiding having to direct model the same change on each individual copy.
As I said, the enhanced direct modeling is not the same thing at all as the history feature, but enhanced DM does make history both more powerful and also more likely to “get confused”. In the above example about aligning to a sketch, to use history, Shapr just tries to repeat exactly the same steps you’ve already done, but without the sketch, it wouldn’t be able to.
But even not using the history at all, you still have a direct modeling issue. If you remove the sketch, the body has nothing to align to — and will go back to where it was previously. Exactly the same as if you delete a cylinder (or its sketch) after you chamfer it. The chamfers will disappear from view when the cylinder does. All of the steps will still be in the history list because Shapr is keeping track of your actions for possible use, but the steps will have errors because of the missing references.
