The pink elefant

[Dade]

Spectral rendering done in LuxCore

(who is used to old LuxRender renderings can easily spot the rainbow-ish white on early stage of the rendering)

This is just the result of a test (direct light only) to check if the general idea can work. I think it is worth some further investigation. It would be the perfect solution:

- it is optional (no cost for normal RGB rendering);
- it does require very little code changes;
- it works on GPUs;
- it works with path, bidir and everything else.

P.S. The pink elephant is a quote from: http://www.luxrender.net/forum/viewtopi ... =8&t=12454

[Sharlybg]

- it is optional (no cost for normal RGB rendering);
- it does require very little code changes;
- it works on GPUs;
- it works with path, bidir and everything else.

Wow incredible move ! thanks you so much for sharing such juicy news with us. can't wait to see more screenshots with this (indirect light/ glass render). But take your time. with such great features it's worth to be patient. .

the pink elephant is going to be a small white mouse in your labs

[Piita]

Ah, spectral, old friend. I missed you. You do require a lot of render time in order to look good but when you are done you sure are gorgeous
Awesome work, Dade!

[neo2068]

wow, great news. Looking forward for next year development.

[Dade]

Normal rendering (BIDIRCPU):

Spectral rendering (BIDIRCPU):

P.S. at the moment, I'm not even sure if it is theoretically correct, for sure, it is damn good at faking it.

[Dade]

[Sharlybg]

P.S. at the moment, I'm not even sure if it is theoretically correct, for sure, it is damn good at faking it.

wow it is very very beautifull and very real. And i also think it is a very well integrated code. I ve never seen this before with a renderer ( the possible to activate and desactivate spectral rendering on the fly). Bravo .

[Dade]

Added the support glass dispersion on GPUs:

I have merged the experimental branch with the main one.

Glass dispersion can be enabled using the ".dispersion" flag in Glass material definition. Volumes/Glass IORs can now accept 3 values instead of 1 (red IOR, green IOR, blue IOR). For instance:

Code: Select all

scene.materials.Cubo_Prism_01_MAT.type = glass
scene.materials.Cubo_Prism_01_MAT.kr = 1. 1. 1.
scene.materials.Cubo_Prism_01_MAT.kt = 0.8 0.8 0.8
scene.materials.Cubo_Prism_01_MAT.ioroutside = 1.0 1.0 1.0
scene.materials.Cubo_Prism_01_MAT.iorinside = 1.28 1.4 1.52
scene.materials.Cubo_Prism_01_MAT.dispersion = 1

P.S. you can still use a single value for IORs (but indeed there will be not dispersion).

[B.Y.O.B.]

This is pretty cool.
It's not even much slower than without dispersion, both attached images were rendered for 16 minutes.

Volumes/Glass IORs can now accept 3 values instead of 1 (red IOR, green IOR, blue IOR).

How should we expose this in exporters?
Should we allow the user to set 3 separate values?
Or would it be better to have only one IOR-value in the UI and have a "Dispersion Strength"-slider which specifies the diverting IORs?

For example:
IOR: 1.5
Dispersion Strength: 0.02
-> exported as iorinside = 1.48 1.5 1.52

By the way, I'm getting a crash when using Tiled Path + dispersion when I stop the render.

[Dade]

How should we expose this in exporters?
Should we allow the user to set 3 separate values?
Or would it be better to have only one IOR-value in the UI and have a "Dispersion Strength"-slider which specifies the diverting IORs?

For example:
IOR: 1.5
Dispersion Strength: 0.02
-> exported as iorinside = 1.48 1.5 1.52

The "strength" solution sounds a lot easier to use (and more artist oriented).

I could potentially add, in the future, the support for tabulated texture in order to potentially have a different IOR for each visible wave length (at the moment, the IOR is just interpolated between the 3 RGB wave lengths). But it is frankly the kind of feature that 99.999999999% of Blender users are never going to use.

By the way, I'm getting a crash when using Tiled Path + dispersion when I stop the render.

Uh, I never tried with TILEPATH, strange, going to check ... it doesn't seems to happen here (it may be a different problem, not related to dispersion), can you post how reproduce the problem.