How to lay 2 layers on top of eachother without deforming any colors?

[burny_8790]

I want to overlay the rustnode on top of the node with the blue material, without transforming the color information from the blue material in any way. How can this be achieved?

[Marco Vitale]

To achieve warten you want, you need to use a mask for your rust and use the mask input of the final blend, set the blend mode to copy or switch and let the b/w mask drive the areas, where the rust layer is used.

Stay healthy and creative Marco 

[Luca Giarrizzo]

Hi! 

That is correct, thank you @Marco Vitale!

If I may, here is a little nugget of information that can help in the future: the difference between 'Copy' and 'Switch' blending modes is that 'Switch' is specifically optimised to only use one of the inputs of the 'Blend' mode if 'Opacity' is set to 0 or 1. In that case, the other input is not computed at all. This can significantly optimise graphs.

So you can think of 'Switch' as a hard 0/1 branching device, whereas 'Copy' is for any blend in between.

Additionally, 'Switch' performs a straight linear interpolation on all RGBA channels (precisely because it is purely a lerp we can optimise), whereas Alpha can be managed differently in 'Copy' mode according to the 'Alpha Blending' parameter.

I hope this is helpful and informative!

Best regards.

[Marco Vitale]

I was guessing so, but now you confirmed it. Thank you, stay healthy and creative Marco