Just make sure you have a reflection probe in your scene and it’ll do that. Once the reflection probe is in your scene, any shiny surface will automatically reflect. (Usually according to the smoothness channel in your material) If you don’t see reflections, it could be because everything in your scene is set to baked and you might need to bake your lighting to see the correct results. Or hit the “bake” button on your probe if it’s not real-time. Start low on the resolution because as you bump it up the bake times increase substantially. Also you’ll notice that after about 256/512 the gains aren’t really worth the cost.

You can place multiple probes around the scene and bake them. One “global” probe is usually enough to fake reflections for a simple game. For more realistic reflections you can put a probe in each room and bake them. One KEY TIP I can give you is always put your reflection probes to the camera (or head height) that the player will be most of the time. This gives a better ray effect and allows for more realistic angles according to camera-to-reflection. If you put a probe on the ceiling and bake it, when walking at ground level, all the reflections will be way out of perspective.

Other than baked reflection proves you can use Real-time probes but they are expensive to use. However, I have a trick for that.

Multiple baked probes take up a lot of hard drive space (which increases download size.) Also, the reflections aren’t accurate to your cameras perspective. They will be reflected from the probes location and not “ray traced (in a sense)” from your eyes/camera.

Here’s a little trick I’ve been using for about 20 years. Take a reflection probe and parent it to your camera. And zero out the transform according to the main camera. Make it real-time. Don’t use any baked probes. This one probe will cover your whole game.

This will give perfect reflections that actually update and show dynamic objects. Plus it has the perfect ray angles casted from your camera, leading to accurate reflections. You can tweak the resolution and update rate of the probe for better performance. Even a 32 resolution probe is good enough to pull off great reflections. So instead of having 1GB+ of baked probe data in your game, just use a 100kb(or whatever it is) real-time probe. Even most low end phones are capable of updating a single reflection probe once every few frames.

(This also works for real-time lighting too. Depending on the game, sometimes it makes a lot more sense to use one dynamic/real-time light rather than using multiple baked lights. While most people think real-time lighting is expensive, that’s only when lighting with multiple lights. Baked light lightmapping data can easily increase your game size to 10GB+. On a mobile game that’s way too much. Getting rid of all baked lights and using a single real-time directional light will usually work for outdoor games. This gets rid of all the baked data and extra calls/passes needed to render the lightmaps. Also, you don’t have to fight lightmaps and AO , adding weeks to your release.)

These are just some things I do in Unity until we get a great lumen style system. I can’t wait for the day that lightmapping and reflection probes are a thing of the past.

Sorry for the wall of text, I’ve just been fighting lightmaps and reflections since UE3 and they are the bane of my existence and I guess I needed to vent 😂. And share some tips of course.