Download

Dynamic light and reflections

I’ve created a scene with a fully interactive dynamic directional light(the sun). Which looks OK for now.
I’m still trying to learn the more about the advanced principles of lighting and reflections in UE4.

One of the issues with reflections under a dynamic light, seems to be that the reflection itself is not dynamic, causing the reflection to capture the scene at launch and not updating itself as a light source may affect the surrounding environment differently over time. I.e; a window shows the same reflection at night and day.

I learned about the “recapture sky” blueprint node which is very costly, but was wondering if anyone has encountered a similar challenge and perhaps found a different solution?
Perhaps a moving point light in a wet environment?

I’m currently trying to learn how to achieve realistic environment while attempting to reduce the costs of dynamic lighting.
I suppose it’s about finding that middle ground.

Any insight is appreciated!

Yeah, you need to recapture skylight but you can do it every hour(about every 15 degrees of sun rotation) or so. And dont even think about using a point light as sun, it wont work.

Thanks Jacky!
I’ll do some more work on it. I’m actually letting the player control the day/night cycle; a player may speed up the time or reverse it. So it’s going to be some issues there, regarding performance.
No, I have no plans of using a point light as the sun. Was intended as a simple example similar to my issue; Think of a wet floor with reflections. Above the floor there is a light bulb moving from A to B. The light bulb lights up different parts of the surrounding environment as it moves. How would you make the reflections of the wet floor change accordingly?

Oh, i see. You get SSR(scren space eflections) for dynamic lighting and when you place a point light into a night scene the floor captures the reflections of whatever you see on the screen.

reflect_1.JPG

And if you want the improve it even more you can place reflection capture actors wherever necessary:

reflect_2.JPG

You may need to put this command r.DiffuseFromCaptures=1 into ConsoleVariables.INI file in your engine folder in order to activate this dynamic lighting feature for reflection capture actors.

It is not some button on the interface allowing that ?

Tried adding the command, but no luck.
Would be nice an interface button, can’t seem to find one though…

As I’m circling in on my issue, I realize there might be some threads on this already, but would love some discussion nonetheless.

A pink static point light illuminating a small table. The “glass” reflects accordingly:
reflection_static_PointLight.jpg

The same light, converted to be dynamic/movable:
reflection_dynamic_PointLight.jpg

As far as i understand, it should be possible to achieve a similar effect with dynamic as with static light, but at a great cost?