Best practice for complex solids additions/subtractions

[line-weight]

Let's say the object I want to end up with can be made from the following objects, added and subtracted as follows:

 

(A+B) - (C+D+E)

 

It could also be made, from the same basic objects but as follows:

 

(A+B) -C -D -E

 

Or

 

((A+B) -C) - (D+E)

 

This is an object that I want to be able to edit by going back to edit any of the objects A-E, so it will stay as an addition/subtraction and is not to be converted into a generic solid.

 

Other than the configuration that's most convenient for me in terms of subsequent editing, is one of these better than the others, for any reason? For example the first option involves 3 operations (an addition, another addition, then a subtraction) whilst the second involves 4 operations (an addition and then three subtractions). Does this have any significance for things like memory, or likelihood of the resulting object getting corrupted?

 

In reality the objects I'm wanting to make will have more than just 5 component solids.

[EAlexander]

Well curious about this, but I don't think it matters which one. Some of them make editing, say, C easier with less clicks, but I wouldn't think it really matters. Curious what others think. 

 

This is definetly a case where I would keep it parametric for the design development phase, but then I would throw a copy onto a hidden layer or separate file in case I need to adjust later, and convert the original to generic solids once it's locked in to save on overhead. 

[line-weight]

4 hours ago, EAlexander said:

 convert the original to generic solids once it's locked in to save on overhead. 

That's another question I had - does doing this make a significant difference to overhead, either when zooming around in OpenGL 3d views or when things like section viewports are generated.

[EAlexander]

I don't think it helps with live feedback much, but overall on large projects it can cut down on file size. 

[Pat Stanford]

I have no definitive proof, but my expectation is that fewer operations with more objects will be more efficient. Every operation takes some overhead and by doing less operations that overhead is reduced.

 

So maybe something like (A+B) - (C & D & E) where C, D, E are all separate objects but selected and used in a single Solids Subtraction.

 

But in reality unless you are designing something with hundreds of operations that you will be regenerating often, the computer is way faster than my brain. So it is often best to just do what makes sense to you.

[Benson Shaw]

2 hours ago, Pat Stanford said:

So maybe something like (A+B) - (C & D & E) where C, D, E are all separate objects but selected and used in a single Solids Subtraction.

I  think this is good strategy.

 

Also, sometimes it can be helpful to edit an existing solid subtraction containing several subsequent nested operations with goal of reducing the number of nest layers. But work on a dupe object for safety.

Eg (A+B) -C-D-E can be converted into (A+B) -(C+D+E)

- Dbl click repeatedly to access the E layer edit space.

- Select all, copy>delete or cut (empties the E layer)

- Exit the E layer (now drawing is in the D edit layer, E ceases to exist)

- Paste, then select all>cut (empties the D layer)

- Exit the D layer (D is gone, drawing is in C edit space)

- Paste (everything from CDE in same edit space)

- Exit, exit as needed to return to drawing space

 

Not always useful but can relieve some confusion in a deeply nested object. Probably more useful for combining nested solid addition layers than for subtractions. 

 

2 hours ago, Pat Stanford said:

So it is often best to just do what makes sense to you.

That’s for sure!

 

@lineweight  great question!

 

-B

Edited November 18, 2019 by Benson Shaw
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