Custom preview on python component - minimal example?

[Toni_Osterlund]

I’m trying to understand how to preview geometry that is created in a class object, but is not explicitly output.

Here’s a simplified example of what I’m trying to do.
How can I get the cylinder to show on the first component, without outputting it?

Preview.gh (6.5 KB)

[AndersDeleuran]

Hi Toni, I shared a bunch of content over here that goes through how to draw things with GHPython, that should help you get going I imagine:

GHPython Content From AECtech+ Barcelona Workshop

Hi All, I ran a short GHPython workshop at the AECtech+ event in Barcelona. I used this GitHub repository for sharing files with the workshop participants, and thought I’d share all the content here as well. Here is the workshop and content descriptions/links from the GitHub readme file: Dynamically Drawing and Reacting to Things with GHPython There is more to running GHPython components in SDK Mode than compiling plugins. We will demonstrate, explore, and combine these overlooked features th…

[Toni_Osterlund]

@AndersDeleuran
Thank you for the link. Quite comprehensive package.

If I understood correctly (?), Rhino.Display.CustomDisplay only allows for curve/polyline objects, but works in procedural mode.
For 3D objects using eg. DrawViewportMeshes, would need to switch to SDK mode.

[AndersDeleuran]

@Toni_Osterlund

If I understood correctly (?), Rhino.Display.CustomDisplay only allows for curve/polyline objects, but works in procedural mode. For 3D objects using eg. DrawViewportMeshes, would need to switch to SDK mode.

Yup that’s correct. One could probably implement a display conduit in procedural mode as well, but the Grasshopper component SDK drawing methods are likely a lot simpler to implement. For a shaded cylinder, I think you would need to cast to brep and use these two methods:

How to colour a brep in GHPython and visualize it in the Rhino?

No you need to implement the DrawViewportMeshes and DrawViewportWires methods in SDK mode. Here’s a quick example extending the file from the thread I posted above: [2023-06-06 12_56_02-Untitled - Rhino 7 Educational - Perspective] 230606_GHPython_DrawViewportWires_00.gh (25.6 KB)

Though there is also a wire drawing method specifically for cylinders.

[Nils_r]

@GHPython Content From AECtech+ Barcelona Workshop

GitHub repository

Thanks for the link to the gitHub! It took me a couple of hours to understand the preview via python components but when I had your examples I immediately could follow along! Saving my day

[AndersDeleuran]

Ah that’s great to hear. Glad it was useful to you