GH Sliders / controllers in web viewer not showing up


Hey there,
I realise this is a new-ish feature of Speckle, so might not be fully implemented yet, but would anyone be able to help me get Grasshopper sliders to appear under the “controllers” bit of the speckle web viewer? I’ve found another post which recommends right clicking speckle sender component and selecting “enable remote control of definition” but the controllers part of the stream is still empty. I’ve tried disabling firewalls and all that jive, but still no sliders appearing, I’m guessing there is another step involved that I’m missing?


Hello @EKM, what’s not documented yet is that the sliders you want to show up need to have SPK_IN as part of their name :grimacing: Here’s an example:

As well, the sliders work best when dragging the knob, while clicking directly to a location might not trigger a compute request.

Let me know if it works out!


Wahoo - wonderful!!! Thank you - all is working very well :smiley:


One more question: Is it possible to get the web-viewer slider to snap to integers? Eg. if I wanted to cycle through options 1, 2 and 3 & snap to those numbers?



I guess having control over this bit:


That’s for sure possible, but I’m not sure of the general bandwidth for this at the moment… AFAIK, slider info is passed with information about their decimal places, but @mswaidan’s down under now, and so am I :slight_smile:


@EKM Yes, I’m totally swamped at the moment and haven’t been keeping up on viewer improvements, but we should be sending the slider increment value so you can control int / float / precision from the GH definition. Can you open an issue at so I don’t forget about this?



Hi Dimitrie and Mathew, first of all thanks for the amazing work. (New .rhi installation runs great). The SPK_IN: is a great tip, great to have sliders on a web viewer with such an easy set up! I was wondering if there is a similar way to store the design space options offline so Rhino doesn’t need to be open? Thanks again!


They are stored on the server, as children of the original stream, so there is a way to do retrieve them. There’s also the possibility to precompute the solution space, as per the now defunct beta speckle and speckle streams, so you don’t need rhino open.

It’s a lot of ui legwork; it will happen, but for now, unless you wanna get your hands dirty, this is not available out of the box :crying_cat_face:


Hi Dimitrie, I see, thanks for the info! I remember the feature on previous speckles indeed - not easy to retrieve those at the moment from what I see. Precomputing the design space is possible also with the “fly” component of Ladybug. Mainly I wouldn’t know where to feed an output csv (with a format something like input_1, input_2, …, input_n, geometry_json). any tips where to look first in case I can work towards that direction? Cheers!


+1 for this functionality. I don’t really use Speckle much right now but this functionality would really make it valuable! I remember using Speckle streams for this reason.


Hey! actually, on the viewer in hestia, they’re back.

First step: “select enable remote control” from your grasshopper sender:

Second step: name your sliders! For them to appear in the browser, they need to contain “SPK_IN” in their name.


Third step: go to the controllers tab of your stream and hit “refresh”.

Finally: profit!

As a warning, it’s probably still buggy as I haven’t tested it properly yet.