Additive/Subtractive Functions

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Jason C. Wells
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Additive/Subtractive Functions

Post by Jason C. Wells »

CAD packages I've used all provide two functions of a particular type. There is an additive pad and a subtractive pocket. I've often wondered why the software doesn't have a single function to replace the two but with an add/subtract checkbox provided in the input dialog. There'd be half as many icons on the screen for one. There'd be half as many functions. Occasionally I have wanted to turn an additive feature into a subtractive feature but had to "do over" instead of just swapping the hypothetical checkbox.

I just worked an example where having a subtract option to the loft function would have avoided the need to do a boolean cut.

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Jason
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sgrogan
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Re: Additive/Subtractive Functions

Post by sgrogan »

See here and here
"fight the good fight"
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NormandC
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Re: Additive/Subtractive Functions

Post by NormandC »

In the second link, ian.rees' post in 4th page sums up what's my opinion on the subject.
Jason C. Wells wrote:I just worked an example where having a subtract option to the loft function would have avoided the need to do a boolean cut.
Were you using 0.16? In 0.17 there is a subtractive Loft in Part Design.
triplus
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Re: Additive/Subtractive Functions

Post by triplus »

Hi Jason.
Jason C. Wells wrote:CAD packages I've used all provide two functions of a particular type. There is an additive pad and a subtractive pocket. I've often wondered why the software doesn't have a single function to replace the two but with an add/subtract checkbox provided in the input dialog.
This is interesting question. I would say it depends on how much and how the tool is used. I do imagine Pad/Pocket tool is used often and in a way you switch between one or another unpredictably. Therefore instead of providing dialog each time to choose the Pad/Pocket it is much faster to have them as separated buttons.

Switching between reference constraints and constraints is much more predictable as usually you work in scopes and you can easily change existing geometry by using toggle button. And here is where you do have a point:
Occasionally I have wanted to turn an additive feature into a subtractive feature but had to "do over" instead of just swapping the hypothetical checkbox.
From FreeCAD perspective you are basically talking about feature property. Yes indeed if such property would exist this would make sense. That is to toggle the Additive/Subtractive property of existing feature. Similar to the approach we choose and can toggle between reference constraints and constraints.
There'd be half as many icons on the screen for one. There'd be half as many functions.
In FreeCAD currently we have 2 standard ways to get more space on toolbars:
  • Menu with list of tools in it
  • Toggle toolbar
Looking at the mentioned toolbar:
Tools.png
Tools.png (38.6 KiB) Viewed 2444 times
As you can see a lot of tools have already been squeezed into it. Additionally trying to reduce the space by using for example toggle toolbar could get us some extra space but i guess not a drastic improvement. There could be toggle button on it to toggle existing features from/to Additive/Subtractive but as we likely won't be toggling Additive/Subtractive tools with it existing feature property might make more sense.

P.S. But i do imagine having such feature property would/could break topology. That is if you have for example some features that use Pad as a external reference and you change the Pad to Pocket you break all the relations and have to start over from that point on.
jmaustpc
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Re: Additive/Subtractive Functions

Post by jmaustpc »

As others have said, this has already been recently discussed at great length. Repeatedly discussing the same thing time and time again is a waste of time, and potentially slows and frustrates developers. We need to make decisions once and then move on.
Jason C. Wells
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Re: Additive/Subtractive Functions

Post by Jason C. Wells »

I'm three months late to the the party. The links above are great discussion with everyone hitting all the salient points. I want to necro that thread, but I won't. :)
triplus
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Re: Additive/Subtractive Functions

Post by triplus »

Jason C. Wells wrote:I'm three months late to the the party.
And that is OK and you for sure didn't waste my time.
Jee-Bee
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Re: Additive/Subtractive Functions

Post by Jee-Bee »

Jason C. Wells wrote:I'm three months late to the the party. The links above are great discussion with everyone hitting all the salient points. I want to necro that thread, but I won't. :)
FC is a few years back on related to other CAD software… so maybe over year or tree (at least after the assembly module) it can swapt. ;)
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