Hi Ed, so also there's one other issue with the AutoCAD Trim workflow, which is that a combination of picking the object to be trimmed along with the area of it to be trimmed all in one step can sometimes be difficult with surface trimming, especially when working in the 3D view.

Here's an example - here there is a circle at a Z level above the sphere and I want to trim out a hole where its projection intersects the sphere:



With MoI's trimming workflow, you select the sphere, then run Trim, then select the circle as the cutting object and then it shows you the various fragments and allows you to select them like this:



Having those fragments generated and displayed on the screen can make it easier to see where they are so you know exactly where to click.

With the AutoCAD type sequence where you would pick the circle first, you don't get to see all the fragmented pieces and instead you would have to kind of try to imagine where on the sphere you're going to need to click to specify the zone to be cut, because with the AutoCAD way selecting the object to be trimmed and the location to trim is all done with one click...

That's not an issue with 2D curves really because it's easier to see that, but with surfaces and projections it becomes more of an issue.

The ability to be flexible and work well on both curves and surfaces as well was an important aspect for MoI's Trim workflow design.

- Michael

Hi Ed, also another thing is that MoI's Trim workflow allows for another function which can come in handy which is being able to specify "Pieces to keep" or "Pieces to discard" when you're selecting the fragments. The AutoCAD method is limited to only being able to specify pieces to discard.

Here's an example - here I am trimming a sphere by a whole bunch of little cutting pieces:


The way MoI's Trim workflow is set up, when you get to the stage where you are clicking on the fragments, there is an option for which mode you want to use, whether the pieces you select will be discarded, or whether the pieces you select will be the ones that are kept and unselected ones discarded, it's here:



So for example with this case here instead of picking all those little pieces after switching Mode = Keep, I can just pick the one big piece instead like this:



And get the same result as if I had picked all those little pieces to remove:




This can come in particularly handy with surfaces when the surface is partly submerged in some other surfaces or solids where it is hard to reach all the little pieces that you want to get rid of but the pieces that you want to keep are often larger pieces that are more on the outside of the structure.

It can come in useful with curve trimming as well though when you're working with some larger batches of stuff.

It's another thing that works more easily with MoI's Trim function with having the fragment selection part as a distinct separate stage of the command.

- Michael

Very bad souvenirs of tocad :)
Even a nightmare for me :)

Thanks for the replies Michael. You convinced me about the trimming part but what about the extend one?? You still can press a key and turn the mode into extend and use every object as a boundary. I think it would be very very useful and a time saver!

Hi Ed, well I'm not sure how that would work to try and wedge in extend functionality into MoI's current Trim command with its current workflow.

You see, the main way to select the object that you're going to trim is to select it _before_ you even run the Trim command.

Do you mean that you would want MoI to remember if you held down shift when you were selecting objects, and to perform a really different result in the command just because of that key being held down before you even ran the command? That could potentially be very confusing it seems.

Also there is already an Extend command that allows you to extend lines to boundaries, it's available right next to the Trim button here:




If Trim also did extensions, then what would you want to happen with the current Extend command that already does that stuff, would it be removed?

But then that causes a problem of a lack of discoverability - that's when users can't figure out how to do something because it requires special modifiers or things like that which are not immediately apparent. By this I mean that if the only way to extend things was by holding down the shift key while you were in Trim, it is likely that a lot of people would never find out how to do that...

So instead of trying to wedge it in to the current Trim command where it does not really fit, that would be more likely something that could be added as a completely separate "AcadTrim" command later on at some point as a plug-in.

- Michael