An Incredible error about Point On Curve Component

When I Using the Point on Curve Component Of Grasshopper, to get the Point on the Curve, I Got an Very strange Problerm, And I think for an long time, and I can not think out what wrong with it . The Input Paramater type is an Custom Paramater Type derive from GH_Curve:The Detail is Show at the picture

Update:

The Code is on the attachment as below

Attachments:

WriteXML.cs, 3 KB
Type.cs, 16 KB
Param.cs, 4 KB

Replies to This Discussion

Permalink Reply by David Rutten on December 9, 2016 at 11:04am

Yup, the Point On Curve object is weird in this respect (probably qualifies as a bug). It inherits from GH_Param<GH_Point>, however it needs to take in curves, so it cannot rely on the standard conversion algorithms. Turns out all it tries is GH_Curve.CastFrom(remoteGoo) and throws an exception if that fails. It doesn't try to then do remoteGoo.CastTo<GH_Curve>. It probably should.

Looks like at the moment there's nothing you can do about this.

Permalink Reply by cughudson on December 9, 2016 at 6:41pm

But why the point on curve object show the error convert from Curve to curve failed, wbat the realationship between Curve and curve?

Permalink Reply by David Rutten on December 10, 2016 at 2:35am

Just because they have similar names doesn't mean they are the same type. Rhino has a Matrix type, so does Eto, so does MathNet. But they are all completely different types as far as the computer is concerned. Any conversion from one to the other must be specially coded up by someone.

The type you are putting in is not GH_Curve and has an unknown type id. I agree that the conversion could have worked, and should have worked, but at the moment it's an unhandled case.

Permalink Reply by cughudson on December 11, 2016 at 6:08pm

So If I wan't to make the point on curve object work when I input my Custom Curve Paramater derive from GH_Curve work . What I can do for this? Thank You

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