Is it possible to add functionality to existing Grasshopper components?

Replies to This Discussion

Permalink Reply by David Rutten on August 5, 2011 at 4:23am

Hi Thomas,

 

I've never actually tested this, but you can try deriving a class from Grasshopper.Kernel.Graphs.GH_AbstractGraph. It should work, I' just never tried defining a Graph in a GHA dll before.

 

You can find useful class and method comments on IGH_Graph and GH_AbstractGraph.

 

--

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Thomas Bildsøe on August 5, 2011 at 4:48am

Hey David

 

Cool, I'm gonna try this!

 

Thanks

 

 

 

Permalink Reply by Thomas Bildsøe on August 7, 2011 at 1:41pm

Hey David

 

It worked. I derived a class from GH_AbstractGraph. Then just removed the lines drawn to indicate the tangent handles of the bezier curve and changed:

 

   this.m_crv = Rhino.Geometry.Curve.CreateControlPointCurve(cv, 3);

 

to:

 

   this.m_crv = Rhino.Geometry.Curve.CreateInterpolatedCurve(cv, 3);

 

I'm looking into adding/removing points from the curve, but this doesn't seem to be as easy as adding another Graph type. And I wasn't able to find the class and method comments?

 

I'd be happy to share the component if anyone need it.

 

/Thomas

Permalink Reply by David Rutten on August 7, 2011 at 2:11pm

It's been a long time since I looked at the GraphMapper code, but I think it's not possible to add grips through mouse events. Seems that when the mouse is clicked more than 10pixels away from a grip, it simply ignores the click.

 

I think your efforts will be better spend trying to write a component that uses a Rhino curve to process data, at least then you'll have all the Rhino commands at your disposal.

 

A hack would be to have dozens of grips in the (0,0) coordinate, and to ignore those during evaluation. Only when you drag one of these grips off the (0,0) coordinate does it become part of the graph curve. But that's über-icky.

 

--

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Thomas Bildsøe on August 14, 2011 at 5:16am

What about setting the number of grips as a paramter for the component? and then pass it on to the actual graph?

 

Would this be possible?

 

/Thomas

Permalink Reply by David Rutten on August 14, 2011 at 8:01am

It's not a component, like most objects in the Special tab, the Graph Mapper is a parameter (Gradients, Legends, Custom preview, Galapagos and Scribble being the exceptions). As such, it can only have a single input and a single output. 

 

Also, to make this possible I'd have to write the code and re-release anyway, so I might as well code up a mechanism for adding grips the easy way...

 

The GraphMapper UI needs some work anyway, I want to add the ability to pan and zoom the graph as well.

 

--

David Rutten

david@mcneel.com

Poprad, Slovakia