1.Why use Fresnel node as alpha input of Lerp node to mix air and water's IOR (Index Of Refraction) ? It looks good when I apply this material to a sphere mesh , but I can see no refraction effect when I apply the material to a cube mesh .
The material network from the tutorial is like this:
2. Why use a number as the input of the Refraction channel could cause weird effect？ I mean in real world , the IOR of a uniform medium should be a constant . I set the Refraction channel to a constant values 1.33(IOR of water) in the following pictures .
I applied the material to a sphere mesh . A large area behind the sphere was focused on the material .
The spere mesh's effect is kind of acceptable even though it's weird . But when I applied the material to a cube , it looks like this as long as I didn't look straight to it :
you’re using fresnel. this means when you look at it from the front and the polygons are “looking back at you” you get an IOR of 1.0, and an IOR of 1.0 is just the thin air. this is the correct behavior according to your material
with the sphere you don’t notice it because the polygons are facing outwards (and not towards the camera when you look at them from the front). it’s just that at the cube there are no grazing angles
what’s the expected behavior when looking at the cube?
I expected the pipe mesh to be what you'll see when you see it through water : it should be thicker than it is , and bent .
This picture comes from the same tutorial . the pipe/stick is bent , but it ignores the thicker effect .
I was confused with the Fresnel node because I thought it wouldn't be right . And in fact it is not as I thought , at least it's not when I applied the material to a cube . I don't understand why they put it in a tutorial.
well you said you’re mixing the IORs of water and thin air.
if you just want water then yes, you should not use the Fresnel node
I also don’t understand why they would put it in a tutorial, and with no explanation why no less. mixing IORs like that even strikes me as ‘not physically correct’ which was the original purpose of this new refraction implementation :eek:
