Back in January, Derek Elliott did a tutorial on getting brighter shadow caustics without messing up shading on the casting object – I recently was trying for the effect but couldn’t get it to work. I went back to 3.4.0 (what he was working in) to try it, worked fine. Opened the same file in 4.0.2…

[image] KickAir_8P: which is what the Light Path > Diffuse Ray into both the HSV Factor and IOR is supposed to do, and it isn’t anymore: Not quite sure what you mean by “it isn’t any more” in your first example it looks like the ior of the glass surface was also changed. In the Blender logo …

The problem comes from the new principled shader, if I recall correctly some of the inputs are clamped to 1 (base colour for example) If you use a glass shader (instead of the principled one) it looks much more like the 3.4 one. [Caust]

Old IOR has been separated into different settings in new principled shader. You have to open Coat sub-panel and plug HSV node output into Tint socket, too.

[image] DNorman: . . . If you use a glass shader (instead of the principled one) it looks much more like the 3.4 one . . . I’m not coming up with a reason why I’d need the Principled BSDF instead of the Glass BSDF for this, and that restored the bright caustics, thx! However the rest of it i…

[image] DNorman: Not really sure if this is what you are after (I just love plugging nodes in!). My apologies for being unclear, but you got it, that’s what I wanted – thanks oodles! :partying_face: If you don’t mind explaining one more thing for my baffled brain: into the Factor of the fi…

Good question. :rofl: My logic is that it is saying “when the ray depth equals the diffuse ray depth use the simple glass shader (with 1.45 ior), if not use the caustics thing.” The ray depth (from the manual) is: The number of times the ray has been reflected or transmitted on interaction with …

Ok I think I got my head round it. This page explains a bit more: https://docs.blender.org/manual/en/latest/render/cycles/render_settings/light_paths.html [Ray] In our case this: [Ray2] The green diffuse ray comes from the floor, through the glass and to the camera (3 bounces). To produce th…

You’ll recall a few weeks ago Drvquiron posted a photo he took in a cafe of a glass similiar to that, and some Luxcore 2.6 renders inspired by it. Of course we’re doing this in Cycles and Blender 4.X (hopefully lots of 4.X’s ), and I’m not looking for perfection, but kind of this bright caustics ef…

Hi, [image] KickAir_8P: The model in your example is quite similar, evidently effective for caustics etc testing, I’d love to have it! And the Reflection Ray effect in your render contributes beautifully, I think you’re right. You can have it ! :christmas_tree: :blender_logo_64_png:

[image] KickAir_8P: You’ll recall yes I do, I did try to model a similar glass object, I think I am missing some micro displacement in the glass. I will see how close I get, he uses luxcore for his renders, I do miss those reflective caustics outside of the shadow in cycles. I hope they will…

[image] DNorman: I do like the control of the ior for the shadow caustics. Yeah, that plus hyping the shadow color’s Value is crucial for this effect – hopefully the dev’s aren’t gonna clamp anything else that borks it. [image] JaAlVir657: [image] KickAir_8P: The model in your exampl…

Bright Caustics Working in 3.4.0 but Not in 4.0.2

Artistic Support Lighting and Rendering

JaAlVir657 (JaAlVir) December 18, 2023, 7:40pm 10

Hi,

You can have it !