I’m testing sketching in Rhino, but this will go nowhere if there is no such basic thing as an eraser. I was looking in many places but no hack or workaround for that. I’m posting it in a separate thread because this is just a general tool for trimming and deleting pieces of curves with a brush.
This would really unlock some possibilities.
Sketching thread topic for reference:
interesting idea, I’ll circle back and ask you the same question our devs ask me whenever I propose something…
what problem are you trying to solve?
do you have any example files that show the problem or workflow that you are trying to develop?
The problem that I’m trying to solve is that if you want to draw anything you also need an eraser 
. Well, not every analog drawing tool supports that, but every digital one does.
You showed the Testmarkup command, we could use it to draw something but there is no tool that would serve as an eraser as in any other raster or vector drawing program. Rhino has only very CAD-ish tools to trim curves which realistically can’t be used to modify freehand drawed strokes.
If I have a bunch of curves that I want to shorten a bit or erase the middle part of some curves, any regular Rhino command that might do that is absurd to use.
I’m feeling a bit strange posting this erasing example, but ok. Maybe it will help. Erasing starts at 00:12. This is Concepts App fun vector drawing application. If somebody tells me I can do this as well with the Trim command, then this is either a bad example or a big misunderstanding of what sketching is.
That would be a nice addition. I can imagine how this would work with curves and points. Would you expect this to work with other types of geometry?
Curves are the most important.
Another use case that comes to my mind is erasing the whole objects - points as you mentioned, but maybe everything that “collides” with the eraser. There is a SelBrush command, but it works in two steps - firstly you select, and then you can delete the selection. I was trying to loop it in a macro, but the best I could do this way was just a rather poor workaround.
From the eraser I would expect “live” erasing of curves as the eraser moves, even if you hack the SelBrush it’s not giving the live feedback from erasing. In SelBrush command I like how easily you can change the brush size (holding Shift and moving mouse up and down), it would be nice if we could pre-specify some brush sizes and also have this Shift method in macro buttons for the Eraser command.
Other geometries that naturally should work well with the eraser are Hatches. Hatches are just filled regions whose boundaries could be modified by the eraser.
I think it’ll be nice if the eraser only erases the parts of the curve it touches. SelBrush selects the whole curve
Yes, that’s the issue. It was just an example. One awful workaround that came to my mind with the SelBrush method is having curves stored as very dense polylines and erasing sub-objects.
One more thing that would be good to have in the Eraser tool as an option. Specify the Layer that it is affecting: Active Layer only, Selected Layer, All Layers, or other kind of pre-filter. This way we can comfortably use the eraser to only erase hand-drawn curves from specific layers or based on other criteria.
Curves drawn by the Crayon drawing plugin have automatically added names “BrushStroke” so you can distinguish them by the name criteria. Crayon is broken, it has an eraser, but not for the baked curves, but only for some kind of temporary, pre-baked ones.
I logged the request here:
RH-83371 Eraser command
Hopefully we can get something hacked together
I was about to write-up a similar feature request. Hope this gets added!
Hi
Can you make it visible ?
Thanks.
It should be visible to everyone now
@mkarimi and @stevebaer
I want to add my vote for this.
This type of function should find all the possible curve (real) intersections and use them to cut out the selected part. It may also be able to split parts.
This feature is very common on parametric software for cutting the sketches and it make the curve trim operation faster and more “relaxing”.
From my teaching experience almost all the beginner get used to select everything before and then trim, without caring about the 2 step process.
A feature like this will reduced drastically the number of clicks I’ve to do while trimming.
In general the same idea could be extended to all the trim, so surface and solids as well. The tool may have options, like trim has apparent intersection.
