How to Use Indirect Multipliers in Unity

Objective: To look at Indirect Multipliers in our HDRP project.

This is the final article in ‘Building a Beautiful Game in Unity’ series that looks to cover using Indirect Multipliers in a HDRP project. The photo above shows where we are at after incorporating a range of HDRP features.

This option is available on your Light in your project in the Light Settings and controls the strength or intensity of indirect light. Setting the indirect light to below 1 will mean that the indirect light will become duller/dimmer with every bounce. Vice versa if you set the indirect light to be above 1, it will make the light brighter with each bounce.

This is great if I wanted to provide some light to a shadow or a dark place within the sci-fi lab that would make a detail visible for the player.

Indirect multiplier of 1 — Notice the darker corners, not giving off much detail
Indirect Multiplier of 45

The indirect multiplier of 45 is quite an extreme case but you can see the power of the indirect lighting bouncing off the surfaces to light up the dark shadowy corners. This might work well if I wanted to create an emergency type alarm in the room with this light flashing on and off.

This step couldn’t be simpler and all it involves is going to the light source in your Hierarchy that you want to adjust, then jump over to the Inspector and head down to Indirect Multiplier:

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