grain in water

[WAS]

PT glass has shadows disabled for itself. How I did Mandos cockpit, and had direct lighting and shadows in the cockpot.

But it may be the darkness within the model itself. Light seems ambient on that side.

[Hannes]

As far as I remember there's a difference, when you render it as a whole or with separate glass parts not casting shadows. I may be wrong, but I can't check it at the moment. Anyway, it might be worth a try...

[WAS]

I thought that was fixed with introduced or improved glass/volume. I can't see how PT subsurface, water, or [volume] glass would function right if it had [uniform] shadows and not depth. Volume density should be what's cutting out transmission within the volume.

I have a test rendering in default samples, AA 9 now with a little cube and window scene. One separated, other single object.

[Hannes]

Actually there IS a difference. Look at the graininess behind the glass that casts shadows.

[WAS]

I do, but i also notice the glass on the right might as well not exist. No refraction or depth screening, or reflection. :O

Which brings us back to quality control. PT Glass WITH shadow is doing the physically correct simulation, which requires more samples/AA to bring out the realism.

I immediately notice in my tests that PT looks real, but grainy, while no shadow glass just looks fake and like ray tracer. All you see is slight ambient sky reflection, and that is literally it.In my test the way the sun is, it looks like there is no glass, basically, cause all the effects that should be there, are not working.Kinda sums up how PT volume can't work without shadows (or looks entirely different, whatever is happening).

[Hannes]

Actually there is at least reflection (as you can see in the side window behind the door). The glass shader is set to double-sided/thin-walled, so I guess, since the glass is infinitely thin, there would not be much refraction in real life.

[WAS]

Yeah, if there is no light reflection on the surface of the glass, no-shadow PT glass doesn't even exist at all. It's only providing reflection, which can screen the glass in examples like yours where there is a solid ambient reflection.

You are literally just seeing floating reflections. The glass is actually completely transparent if it's not receiving reflection from sky or something. if you mix it ever so slightly with a transluscent default shader (not shadow. the heck) with like a glass blue, it at least looks like glass is there if no reflections are present.

[WAS]

In fact it also almost looks like that no-shadow PT glass actually kills PT lighting. Converts the internal scene to like a ray-traced scene. There is literally NO bounce  inside of the no-shadow PT glass object.

[WAS]

PT with shadow object, you can clearly see the light is bouncing around within the object, and illuminating the interior.

If you aren't benefitting from the benefits from PT in things like this, it wouldn't even make sense to use PT.

In this preview, lighting is set, so there are no reflections on the glass.

• Left is no-shadow glass separated.
• Right is a single object with glass material.

The right is doing the physically correct thing. The left is doing, pretty much nothing. Just a floating reflection shader, that also kills PT bounces. xD

Update: Also there is a weird line within no-shadow pt object that's not part of the mesh. Traced the line in second image. Oh! There is faint ambient reflection, and that is shadow from the right-hand side of the window sill.

[WAS]

Here is the gathered test scene if anyone wants to play with settings, etc.

[Hannes]

The right is doing the physically correct thing. The left is doing, pretty much nothing. Just a floating reflection shader, that also kills PT bounces. xD

Indeed. Quite something to report...

[WAS]

I'm on the fence. To me, it sort of makes sense that if it's not casting shadows, these features wouldn't work properly. Depending on how accurate the glass is, it should be refracting rays that pass through it. Becoming secondary, or whatever, but also having their paths probably modulated at different angles, hence the bounce inside to get that global illumination.

But maybe it should still work without shadows for direct rays, I'm not sure. But it seems to be acting as if it's not handling shadows plus rays.

[Dune]

Once more we have an interesting discussion   Thanks for that. I'll test my (Dorian's actually) house with separated windows, as that has windows all around.

[Hannes]

Since almost not a single model you find on the web can be used right as it is, I have made a habit of separating glass parts of an object each and every time and make the whole thing real world scale. I then work on the textures and save them as TGO. This saves a lot of time.

[Dune]

You got it absolutely right, I totally forgot about it. Separated glass and set to no shadows. Huge difference, and pretty good even with architecture and AA=6. Too bad the glass doesn't work on complete models and rules out shadows. I was under the impression that it did, actually.

Now just wait for the final model to complete this