LuxCoreRender Forums

Hi guys,
I'm once again preparing some automotive renders renders using luxcore but there are a few things I currently can't work out how to do them. They are related to gradients.

I know there is a node called "Blend" to do it and it works quite well but there is one thing I can't do. I want to get the typical "reflected" gradient but I couldn't find a way to control this node to create that effect. I also tried with the "Band" node, but sincerely I didn't understand it. I attach an image of what I would like the final outcome look like, to give you a better idea. Aside from this, I also wanted to create a pearlescent kind of car paint. To do so, generally you want that the surfaces that are facing perpendicularly to your point of view have a certain color whereas the adyacent ones have other (in short, I'm looking to create a color gradient based in the fresnel effect). Is there any way to control the base color like that to make this effect in luxcore? I really will appreciate your feedback!

Regards, saludos
Pablo

PDRA wrote: ↑Tue Aug 18, 2020 6:10 am I know there is a node called "Blend" to do it and it works quite well but there is one thing I can't do. I want to get the typical "reflected" gradient but I couldn't find a way to control this node to create that effect. I also tried with the "Band" node, but sincerely I didn't understand it. I attach an image of what I would like the final outcome look like, to give you a better idea.

You can use the Blend texture to get the basic gradient, then use a Band/Colorramp node to remap it so it is brightest at value 0.5 and starts to get darker again toward 1. The gradient in your example picture seems to be non-linear, maybe exponential. To get that, you can use a math node in "Power" mode.

PDRA wrote: ↑Tue Aug 18, 2020 6:10 am Aside from this, I also wanted to create a pearlescent kind of car paint. To do so, generally you want that the surfaces that are facing perpendicularly to your point of view have a certain color whereas the adyacent ones have other (in short, I'm looking to create a color gradient based in the fresnel effect). Is there any way to control the base color like that to make this effect in luxcore?

You could check if the absorption color is enough for your purposes.
I don't think we have a possibility to use an arbitrary color gradient depending on viewing angle.

For your gradient light Maybe this can Help :
Blendfile: Edit You're fast BYOB : will study you're setup. Mine is using Uv mapping :

Thank you a lot guys!!
Great workaround to solve this issue, you are very creative!
I've been testing them and they work pretty well for what I wanted to do.
It would be great in the future of the development of luxcore a more intuitive tool for gradients. I tend to use them quite a lot and for me it is a bit too complicated as it is right now. Anyway, I know there are other things in the roadmap and you have done gigantic steps with this render engine, but it would be pretty cool to have something like that

B.Y.O.B. wrote: ↑Tue Aug 18, 2020 8:56 am You can use the Blend texture to get the basic gradient, then use a Band/Colorramp node to remap it so it is brightest at value 0.5 and starts to get darker again toward 1. The gradient in your example picture seems to be non-linear, maybe exponential. To get that, you can use a math node in "Power" mode.

You could check if the absorption color is enough for your purposes.
I don't think we have a possibility to use an arbitrary color gradient depending on viewing angle.

Apparently playing with the absorption (color and values) and changing the different colors for the different layers of the car paint can give you the chance to control it and be able to create this effect! However, it would be great to make it possible for other materials such us the Disney. A node like the Fresnel/fallof that 3ds max has would be great for this purpose.

Test 1 - Pearlescent effect (exaggerated) Test 2 - Aproximation to the effect wanted (mix of red and a little orange) Test 3 - Current car paint setup I think I will be using the test 2 approach, even though I like the control over the fresnel effect determined by the IOR value of the test 3 setup has.

All the best, saludos!

IIRC some car paints in the real world also use thin film interference to achieve this effect. In Lux you can use a disney material for this.
To use it, enable "Thin Film Coating" and adjust the film thickness. You can see which colors to expect at which film thickness in charts like here: https://soapbubble.fandom.com/wiki/Colo ... _Thickness

B.Y.O.B. wrote: ↑Wed Aug 19, 2020 7:15 am IIRC some car paints in the real world also use thin film interference to achieve this effect. In Lux you can use a disney material for this.
To use it, enable "Thin Film Coating" and adjust the film thickness. You can see which colors to expect at which film thickness in charts like here: https://soapbubble.fandom.com/wiki/Colo ... _Thickness

That is just great info!!
I will be playing with this for sure
Thank you again!