Bake different lighting setups with Lighting Scenarios

A Lighting Scenario contains the baked lighting data for a scene or Baking Set. You can bake different lighting setups into different Lighting Scenario assets, and change which one the High Definition Render Pipeline (HDRP) uses at runtime.

For example, you can create one Lighting Scenario with the lights on, and another Lighting Scenario with the lights off. At runtime, you can enable the second Lighting Scenario when the player turns the lights off.

Enable Lighting Scenarios

To use Lighting Scenarios, go to the active HDRP Asset and enable Lighting > Light Probe Lighting > Lighting Scenarios.

Add a Lighting Scenario

To create a new Lighting Scenario so you can store baking results inside, do the following:

  1. Open the Probe Volumes panel in the Lighting window.
  2. In the Lighting Scenarios section, select the Add (+) button to add a Lighting Scenario.

Bake into a Lighting Scenario

To bake into a Lighting Scenario, follow these steps:

  1. In the Lighting Scenarios section, select a Lighting Scenario to make it active.
  2. Select Generate Lighting. HDRP stores the baking results in the active Lighting Scenario.

You can set which Lighting Scenario HDRP uses at runtime using the ProbeReferenceVolume API.

If you change the active Lighting Scenarios at runtime, HDRP changes only the indirect lighting data in the Light Probes. You might still need to use scripts to move geometry, modify lights or change direct lighting.

Blend between Lighting Scenarios

To enable blending between Lighting Scenarios, go to the active HDRP Asset and enable Light Probe Lighting > Scenario Blending.

You can blend between Lighting Scenarios at runtime using the BlendLightingScenario API.

For example, the following script does the following:

  1. Sets scenario01 as the active Lighting Scenario.
  2. Sets up the number of cells to blend per frame, which can be useful for optimization purposes.
  3. Updates the Probe Volume blending factor every frame to blend between scenario01 and scenario02.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class BlendLightingScenarios : MonoBehaviour
{
    UnityEngine.Rendering.ProbeReferenceVolume probeRefVolume;
    public string scenario01 = "Scenario01Name";
    public string scenario02 = "Scenario02Name";
    [Range(0, 1)] public float blendingFactor = 0.5f;
    [Min(1)] public int numberOfCellsBlendedPerFrame = 10;

    void Start()
    {
        probeRefVolume = UnityEngine.Rendering.ProbeReferenceVolume.instance;
        probeRefVolume.lightingScenario = scenario01;
        probeRefVolume.numberOfCellsBlendedPerFrame = numberOfCellsBlendedPerFrame;
    }

    void Update()
    {
        probeRefVolume.BlendLightingScenario(scenario02, blendingFactor);
    }
}

Preview blending between Lighting Scenarios

You can use the Rendering Debugger to preview transitions between Lighting Scenarios. Follow these steps:

  1. Go to Window > Analysis > Rendering Debugger to open the Rendering Debugger.
  2. Set Scenario Blend Target to a Lighting Scenario.
  3. Use Scenario Blending Factor to check the effect of blending between the Lighting Scenarios in the Scene view.

Keep Light Probes the same in different Lighting Scenarios

If you move static geometry between bakes, Light Probe positions might be different. This means you can't blend between Lighting Scenarios, because the number of Light Probes and their positions must be the same in each Lighting Scenario you blend between.

To avoid this, you can prevent HDRP recomputing probe positions when you bake. Follow these steps:

  1. Bake one Lighting Scenario.
  2. Set another Lighting Scenario as the active Lighting Scenario.
  3. Change your scene lighting or geometry.
  4. In the Probe Placement section, set Probe Positions to Don't Recalculate.
  5. Select Generate Lighting to recompute only the indirect lighting, and skip the probe placement computations.

Additional resources