Custom fall-off

In the real world, light fades over distance, and dim lights have a lower range than bright lights. The term “fall-off” refers to the rate at which light fades. Alongside Unity’s default fall-off lighting behaviour, you can also use custom fall-off settings.

Progressive LightmapperA tool in Unity that bakes lightmaps according to the arrangement of lights and geometry in your scene. More info
See in Glossary provides custom fall-off presets, which you can implement via script. See the image below the table for a visual representation of how these work, and the code sample below the image for an example of how to use this functionality.

Property	Function
`InverseSquared`	Apply an inverse-squared distance fall-off model. This means the light intensity decreases inversely proportional to the square of location’s distance to the light source. For more information , see Wikipedia: Inverse-square law. This option is the most physically accurate.
`InverseSquaredNoRangeAttenuation`	Apply an inverse-squared distance fall-off model with no smooth range attenuation. This works in the same way as `InverseSquared`, but the lighting system does not take into account the attenuation for the range parameter of punctual lights (that is, point lights and spotlights).
`Legacy`	Apply a quadratic fall-off model. This model bases the light attenuation on the range of the light source. The intensity diminishes as the light gets further away from the source, but there is a very sharp and unnatural drop in the attenuation, and the visual effect is not realistic.
`Linear`	Apply a linear fall-off model. In this model, attenuation is inversely proportional to the distance from the light, and the fall-off diminishes at a fixed rate from its source.

An example of the visual effect of each custom fall-off preset

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Experimental.GlobalIllumination;
using UnityEngine.SceneManagement;
[ExecuteInEditMode]
public class ExtractFalloff : MonoBehaviour
{
    public void OnEnable()
    {
        Lightmapping.RequestLightsDelegate testDel = (Light[] requests, Unity.Collections.NativeArray<LightDataGI> lightsOutput) =>
        {
            DirectionalLight dLight = new DirectionalLight();
            PointLight point = new PointLight();
            SpotLight spot = new SpotLight();
            RectangleLight rect = new RectangleLight();
            DiscLight disc = new DiscLight();
            Cookie cookie = new Cookie();
            LightDataGI ld = new LightDataGI();
            
            for (int i = 0; i < requests.Length; i++)
            {
                Light l = requests[i];
                switch (l.type)
                {
                    case UnityEngine.LightType.Directional: LightmapperUtils.Extract(l, ref dLight); LightmapperUtils.Extract(l, out cookie); ld.Init(ref dLight, ref cookie); break;
                    case UnityEngine.LightType.Point: LightmapperUtils.Extract(l, ref point); LightmapperUtils.Extract(l, out cookie); ld.Init(ref point, ref cookie); break;
                    case UnityEngine.LightType.Spot: LightmapperUtils.Extract(l, ref spot); LightmapperUtils.Extract(l, out cookie); ld.Init(ref spot, ref cookie); break;
                    case UnityEngine.LightType.Area: LightmapperUtils.Extract(l, ref rect); LightmapperUtils.Extract(l, out cookie); ld.Init(ref rect, ref cookie); break;
                    case UnityEngine.LightType.Disc: LightmapperUtils.Extract(l, ref disc); LightmapperUtils.Extract(l, out cookie); ld.Init(ref disc, ref cookie); break;
                    default: ld.InitNoBake(l.GetInstanceID()); break;
                }
                ld.falloff = FalloffType.InverseSquared;
                lightsOutput[i] = ld;
            }
        };
        Lightmapping.SetDelegate(testDel);
    }
    void OnDisable()
    {
        Lightmapping.ResetDelegate();
    }
}

Progressive Lightmapper added in 2018.1 NewIn20181

2018–03–28 Page published

Lightmap seam stitching

Realtime Global Illumination using Enlighten (deprecated)

Unity Manual

Custom fall-off