Using Multiple Post Processing Profiles and Reflection Probes
Let’s take a dive into Unity’s HDRP and see what fun effects can be had by using multiple reflection probes and post processing profiles. Both of these features are available in the Universal Render Pipeline as well, so don’t let the HDRP tag scare you away.
Create a new Reflection Probe by navigating to Light>Reflection Probe.
If your Gizmos are visible, you should see a chrome sphere that is the reflection probe, gathering lighting information about your scene. By default, the reflection probe is set to Baked. That’s why even though it’s inside, it is reflecting the sky box as well as the static elements in the scene (floors and ceilings).
Under the Type option on the reflection probe, change from Baked to Realtime.
Now the reflection probe will properly show the indoor scene.
Let’s create a reflective sphere to move about the game scene like a player. Most players won’t be this reflective or round, but you get the point. It’s currently reflecting the night time sky box. Why is that?
Ah…it’s not inside the volume of influence that comes standard equipped with a reflection probe. That box outline is the area in question, and the player is still on the outside looking in.
As the sphere moves into the box volume on the reflection probe, you can see the reflections on it change from outdoors to indoors.
You can enable the Use Influence Volume, which will tell the reflection probe to only reflect it’s information to objects inside the box volume. This will change how your reflections look so feel free to experiment. Reflections from probes are not perfect screen space reflections, so using your best judgement is a solid course of action.
I am going to use one reflection probe for the interior of this building, so I make the box volume of the probe roughly the same size of the building.
Now the entire room is being reflected upon by a single probe. You can see the difference it makes as I turn the probe on and off.
Here is another shot of the probe reflections turning on and off.
Let’s add another reflection probe outside in the courtyard.
The double layer on the box volume is very useful for easing in on the objects at the edge of your scene. Here the floor can take more or less reflections from the emissive trees based on how close the volume sits.
Moving the player orb from inside to outside now shows correct reflection changes based on the environment.
Let’s see that again with a better shot from the Game View.
Let’s play with some additional post processing volumes to get dynamic changes while moving through the scene. I am currently only using a Global Volume, which affects the entire game scene. Create a new local volume by navigating to Volume>Box Volume.
With the Gizmos enabled, you can see the semi-transparent box volume in the scene view.
Click the Edit Collider button to change the size of the box volume.
Each wall has a node that can be dragged in or out to resize the box. So long as you are viewing the scene from inside the box volume (scene view), or the camera is inside the box volume (game view), you will see the overrides for that local volume.
I need to create or assign a Volume Profile. Either assign an existing profile or press the New button to auto generate and assign one.
Now let’s add some overrides to this empty volume.
The first volume will be a very cool profile, and only use a Color Adjustments override, with a blue color chosen via the Color Filter option.
By default, the Blend Distance is set to 1. This is the distance away from the box volume the viewer can be before the visual changes start to take effect. A value of zero will snap the to view changes immediately, where a larger number will provide a more gradual transition as the camera moves into the volume.
I made the box volume to be the size of the building, and it starts just past the door entrance. Now as the player enters the building from outside, the scene feels much colder and comes with a gradual transition. The blue is a bit extreme to showcase what’s going on, so dial your colors to taste.
I add another local box volume inside the large cool volume. This is a small box volume that sits around this reactor. There is a red Color Adjustment override, as well as some Chromatic Aberration and Film Grain. These techniques can be used to let the player know that hanging out by a reactor might be bad for your health.
Thanks for reading along, and I hope you enjoy playing with reflection probes and post processing volumes!