Hi, I’m finding when making C# components a new behavior Grasshopper in Rhino 8. In the past, I found that DrawViewportMeshes and Wires are always called when rendering the viewport, assuming the component is being previewed. Now it appears that these are only called if the component has geometry …

[image] gruedisueli: DrawViewportWires without testing but i think you need to override public override BoundingBox ClippingBox IGH_PreviewObject Interface All IGH_DocumentObjects that wish to participate in Viewport redraws must implement this interface. …

Indeed, it sounds related to this report: [image] Regression: DrawViewportMeshes/Wires Requires Bounding Box Method Grasshopper Developer Hello McNeelies, As part of testing our BIG pipelines in Rhino 8 I’ve noticed a minor, but quite annoying, regression related to draw…

might be related - if there is only a scripting component, that has preview enabled, it will not work: [image] (Bug) Preview of Script Component Grasshopper Hi Tom - Thanks! → RH-88544 ScriptEditor: No Grasshopper Preview -wim

DrawViewportWires / Meshes only called when there are C# outputs

Rhino Developer

AndersDeleuran May 29, 2025, 5:44am 3

Indeed, it sounds related to this report:

Topic		Replies	Views
Can DrawViewportWires draw GH objects? Grasshopper Developer	7	1532	January 18, 2019
Overwriting DrawViewportWires in C# plugin Shows nothing Grasshopper Developer windows	1	71	January 22, 2025
Cannot preview mesh in c# component Grasshopper Developer mac	0	350	February 18, 2022
Regression: DrawViewportMeshes/Wires Requires Bounding Box Method Grasshopper Developer windows , ghpython	6	225	July 3, 2025
Clarification on preview display Grasshopper Developer windows	5	680	January 21, 2021

DrawViewportWires / Meshes only called when there are C# outputs

Related topics