Referencing geometry in Grasshopper - sometimes asked to select existing objects and sometimes asked to create new


I am a quite experienced Rhinoceros / Grasshopper user but there is one issue that I can’t figure until now. It seems like it came back with the last update.

When you put container components like Point, Line, Curve, Surface etc. and choose an option Set one Point, Set one Line, Set one Curve etc., the behaviour is different for different types. I remember that in the old versions you had to create all kind of geometry in Rhino before referencing, but after some release you were asked to create new Points and Lines instead of selecting existing ones.

What is the logic behind the difference between referencing Points and Lines (which you have to draw, not select from Rhino document) and all other geometry types?

Today I came home after work, opened Rhino which seemed to install some update, opened GH and the behaviour for referencing points changed again. I have to select an existing one.

It’s a minor issue but I wonder if it’s possible to set a default behaviour somewhere in the settings.

Parameters that are specific and considered primitive will ask you to draw (points, vectors, lines, box) Parameters that are not specific will ask you to reference (Mesh, Surface, Geometry, Curve, Brep) because those types have different options that are not easy to create just by clicking (such as degree and interpolation types).

If you prefer to always set instead of draw then just use a geo Param.

The good thing with the point param is that you can edit the points directly from gh by clicking the point param, this will make the gh points actually editable for moving with the mouse.

Hi Michael,
it seems here that I can move the Grasshopper points parameters directly inside the Rhino viewport but I can’t snap the new position nor change the gumball setting of the point parameter. I’m doing something wrong?

it depends on how you reference the point in GH

if your point already exists in Rhino, and when you reference it in GH you chose “Point” from the command line, then you can’t gumball it within GH: it’s a Rhino geometry

but if you reference a Point by Coordinate, you’re not actually referencing a Rhino Geometry, but just the coordinates XYZ of the current snapped location, then GH is generating a Point at that location and you can gumball it within GH:

Hi Inno,
It’s the second case. Why I can’t relocate the gumball?

I think you can only translate the point along X / Y / Z World axis by using the mini-gumball arrows, or move it along the viewport’s current cplane by dragging it with left mouse button, not aware of any additional operations you can do directly from the Rhino view

Yes, I really don’t know why…

I suspect the gumball you see when selecting the GH point parameter isn’t the same one you see when selecting a point in rhino. I agree they should both behave the same way though!

Nothing, it doesn’t work that way.