Blender nearly realtime caustics, dispersion and thin-film effects

[marchik]

Guys, I suppose that we have some problems :D

Frankly, looking at something like this, I feel  annoyance and sadness, because I suspect that we will not see such a level of interactivity for these effects in our beloved Corona very soon.
And we don’t have a physically correct thin-film shader at all.
All this means that I "have to" learn new packages and engines to keep up my level, so I've just decided to poke around a little and share the emotion :D

No complaints about the development team, they do an excellent job. But reality is changing quickly.

[Jpjapers]

This has to be some sort of fake shader effect no?
It looks very good regardless.

[marchik]

This has to be some sort of fake shader effect no?
It looks very good regardless.

I thought about it at first too. Something like the RT Caustics node in the latest versions of Substance Designer. But I cannot say this with certainty. The example from the video with caustics at the bottom of the pool looks quite convincing. In any case, it looks better than the fake shadows from the architectural glass shader.

This video made me so emotional also because at the very moment I saw it - I was rendering a separate caustic pass at 1400px resolution for the last 40 minutes, only to then open AI denoizer, AI upscaler and photoshop and draw masks by hand to leave the most "successful" parts. I'm not even talking about dispersion. And this brought me to despair :D

[Jpjapers]

I cant see any way that it can be calculating physically correct caustics that quickly and the fact that you can art direct the caustics makes me think its totally fake.
I notice that thers no side by side comparison with actual rendered caustics vs the shader.

[marchik]

I cant see any way that it can be calculating physically correct caustics that quickly and the fact that you can art direct the caustics makes me think its totally fake.
I notice that thers no side by side comparison with actual rendered caustics vs the shader.

saw your comment under youtube video :D

[romullus]

I too think that it's totally fake shader, in a sense that it's not physically accurate as it's claimed in the video, but frankly i don't care much about that and i think majority of Corona users would gladly take ultra fast and clean fake caustics and dispersion as long as it looks quite convincing.

[philipbonum]

I too think that it's totally fake shader, in a sense that it's not physically accurate as it's claimed in the video, but frankly i don't care much about that and i think majority of Corona users would gladly take ultra fast and clean fake caustics and dispersion as long as it looks quite convincing.

Yep, I think most of us would, but at the same time it would be best to have disclaimers when turning something like this on, so we wouldn't be fooled in case we actually do need to be exact with the rendering.

If the Corona devs would be open for more fake business, that opens up a whole bunch of other things we could benefit from. Volumetric lights being just one(the standard max one is a pain to work with and is not really that realistic looking out of the box)

This or other shortcuts might be the best way forward if we are to compete with real-time renderers.

[BardhylM]

It is a easy thing to test out:



I would say the model is not 100% right, but close enough to see the point. The video is sped up obviously, but I saw quite an improvement in intensity of caustics with version 10.
As romullus said, wouldn't mind inaccuracy too much If it was in exchange with that speed. If it was possible to use GPU for anything, it would help a lot, even if it meant as a separate Render Element. We could merge those in postproduction.

I also tried to add a plane with displacement above this to simulate water with caustics falling in, but this was the result:


You should just about see where the outline of the object is, don't know If this is how it should be working.
 

[Jpjapers]

saw your comment under youtube video :D

The author replied and it is infact a fake based on the shadow raycasting rather than any sort of refraction.

[Jpjapers]

If the Corona devs would be open for more fake business, that opens up a whole bunch of other things we could benefit from.

I love a bit of fake business now and again

[marchik]

saw your comment under youtube video :D

The author replied and it is infact a fake based on the shadow raycasting rather than any sort of refraction.

I just want to note again that at a comparable speed, we in Corona only have exactly the same fake shadow from architectural glass, but this caustic-like shadow in the video looks clearly better. So I absolutely accept this "fake for beautiful fake" exchange
I am also inspired by the fact that you can get a shader that completely changes the result you get - just by downloading it as an add-on :D

[melviso]

This is awesome. Thanks for posting about it.