C++ How to add custom snap points to custom Rhino object

Rhino Developer
1

Hello,

Is this possible within the Rhino 5 C++ SDK? I have my custom curve object and I want to add custom points in such a way that they appear as construction points when Osnap is on.

Many thanks,
Pablo

2

@mikko, any ideas here?

3

Seems to me this should be possible by overriding CRhinoObject::SnapTo for the custom object. You’ll probably want to call CRhinoCurveObject::SnapTo in it to get the basic curve snapping.

4

Thank you @mikko , this looks indeed the way to go.
Just to know, is there any sample showing how to use it? (mainly CRhinoSnapContext and CRhinoSnapEvent)? @dale?

Pablo

5

Hi @pagarcia,

The suggestion was that if you have a custom object that derives from CRhinoCurveObject then override the CRhinoObject::SnapTo virtual function. Picking will automatically use the “snap to” results.

Does this make sense?

– Dale

6

Hi @dale,

Just a question about the actual use of it. Imagine I want to add ON_3dPoint A to the snapping points of the object. How to do it? I tried this (assume A is globally known):

bool CRhinoCurveObject::SnapTo(const CRhinoSnapContext& snap_context, CRhinoSnapEvent& snap_event) const 
{
       return snap_context.SnapToPoint(A);
}

Pablo

7

Hi @pagarcia,

Call base class first, per @mikko suggesions.

bool CMyCurveObject::SnapTo(const CRhinoSnapContext& snap_context, CRhinoSnapEvent& snap_event) const 
{
  bool rc = CRhinoCurveObject::SnapTo(snap_context, snap_event);
  if (!rc)
  {
    // todo...
  }
  return rc;
}

– Dale

8

Hello,

Is it possible to do something similar from RhinoCommon?

Márton

9

Sorry, no. Can you explain what your looking to do?

– Dale

10

Hey @dale,

To resurrect this topic, myself personally, I would love to be able to add custom snap points to a CustomCurveObject that do not lie on the curve so that a user could snap to those points when dimensioning etc.

– cs

11

Hi @csykes,

I’ve added the request to the pile.

https://mcneel.myjetbrains.com/youtrack/issue/RH-70609

– Dale

1 Like
12

Hey @dale,

Thanks for adding it, I did manager to create this in a hacky way by creating a ray that intersects the curve as a surface and getting the nearest point to the curve and having the custom curve object follow that point around the edges, which gives an-ok-ish “Snap-To” effect. But a native function would be much better

– cs