Techniques for troubleshooting shadow rendering in the Universal Render Pipeline (URP).
By adjusting the shadow bias values you can reduce or eliminate such shadow artifacts as shadow acne, shadow detachment (also known as peter-panning), light leaking, and self-shadowing.
In URP, you can set the shadow bias in the URP Asset and on individual lights.
In the URP Asset, the shadow bias settings are in the Shadows section. The values you set here are the default values for all lights in the scene.
To set the shadow bias values for a specific light:
In the Shadows section of the Light component, ensure that Shadows Type is set to Soft Shadows or Hard Shadows.
Set the Bias property to Custom. Unity shows the properties Depth and Normal. Use those properties to set the shadow bias values for the current light.
Using high shadow bias values might result in light leaking through meshes. This is where there is a visible gap between the shadow and its caster, and leads to shadow shapes that do not accurately represent their casters.
URP has the per-camera limit on the number of visible lights in the camera frustum. For example, on mobile platforms, this limit is 1 Main Light and 32 Additional Lights.
In the Forward Rendering Path, there is also the per-object light limit.
If the number of visible lights exceeds the limit, Unity disables some lights. It might disable a real-time shadow-casting light, which causes shadow flickering.
To avoid this issue, ensure that the number of visible lights in the camera frustum does not exceed the limit. You can get the number of visible lights using the cullResults.visibleLights array of the RenderingData.cullResults API.
The following example shows how to use the cullresults.visibleLights array:
public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
{
int visibleLightCount = renderingData.cullResults.visibleLights.Length;
}