Weird SSR-type refraction?

[anon58292963]

is this supposed to happen? am i just stupid? (4.26)

[BananableOffense]

See the following:

Weird lumen reflections

That looks like refraction. Generally you don’t want to use the refraction on thin, flat planes like glass. Even though technically real windows do refract light as the light enters the glass, upon exiting the glass it refracts is back to face the same direction as the original ray, resulting in essentially no visible refraction. IRL, refraction is often only particularly noticeable of curved surfaces, because the curvature causes the ray to exit the medium still going a different direction than…

[anon58292963]

bruh why does unreal tell me to use that value tho

[BananableOffense]

Index of Refraction values (provided by Epic and found elsewhere) are determined by physics. But because game engines aren’t a perfect representation of reality you may have to make your own adjustments, and sometimes that means using figures that are physically innacruate. The engine documentation also says the following:

“In Unreal Engine 4, we now make use of a non-physical model of refraction, Pixel Normal Offset . The built-in code, using the physical model of refraction for Index of Refraction , is based on how light rays refract as they transfer between mediums, which can cause a lot of artifacts as the scene color is being read from off screen. This can be useful for small objects, like glass jars, where you won’t notice the effect as much, but is problematic for flat surfaces.”

Refraction Using Pixel Normal Offset