Questions related to Arnold Lights

[Riccardo Cecchinato]

Hello!

I have a couple of questions related to the Arnold lights implemented in Gaffer 1.4.8 :

- I am not able to find the Kelvin temperature option in any of these lights, and it is a feature that is very used and useful. Is there a way to have it enabled, maybe via an external node?

- regarding the SpotLights, is there a way to expose the light color as orange input connection? as it is already the case for the QuadLights?

Thank you in advance for your help and your work!

Riccardo

[John Haddon]

Hi Riccardo,

We just expose the parameters of the Arnold lights as they are, and Arnold doesn't have a built-in temperature option. I've attached an example showing how you might set this up using an expression instead. I've just put the `temperature` control in the User tab, but in practice you might build a custom Box which provides all the controls in one place, and omits controls which you don't want to use. Alternatively, you could use the USD/Light menu to make a UsdLux light. These have color temperature built in, and also work in Cycles and 3Delight, and can be exported to USD for use elsewhere too.

Arnold doesn't support connections to the `color` of a spotlight, which is why we don't expose it as an input connection in the UI. But you could assign a gobo filter to the light and texture that instead. I've also attached an example of that.

Hope that helps...

Cheers...

John

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[Riccardo Cecchinato]

Hello John, 

thanks a lot for the quick reply and the useful information, and for your tests! 

I find it weird that Arnold does not allow Kelvin control in Gaffer, since it can be found in all of the other softwares, and they also have an official wiki section related to that.

This being said, the OSL expression solution is simple and effective, I will surely use it!

Regarding the color input, it was so to control the color of multiple spots with one single color input, and I think I'll do it through expressions/parameter drag-drop, therefore having one light leading the others.

Thanks again for the quick support, have a great day!

Riccardo