URP uses the following properties to determine the contribution of Reflection ProbesA rendering component that captures a spherical view of its surroundings in all directions, rather like a camera. The captured image is then stored as a Cubemap that can be used by objects with reflective materials. More info
See in Glossary to a GameObjectThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
See in Glossary:
Note: When performing indirect draw calls, Unity does not support reflection probes in the Deferred and the Forward rendering paths. Unity supports them in the Forward+ rendering pathThe technique that a render pipeline uses to render graphics. Choosing a different rendering path affects how lighting and shading are calculated. Some rendering paths are more suited to different platforms and hardware than others. More info
See in Glossary.
Each reflection probe has a box volume. A reflection probe only affects parts of a GameObject that are inside the box volume. When a pixelThe smallest unit in a computer image. Pixel size depends on your screen resolution. Pixel lighting is calculated at every screen pixel. More info
See in Glossary of an object is outside of any reflection probe volume, Unity uses the skyboxA special type of Material used to represent skies. Usually six-sided. More info
See in Glossary reflection.
In URP, Unity evaluates the contribution of each probe for each individual pixel, depending on the position of the pixel relative to the boundary of the probe volume.
This behavior is different from the Built-in Render PipelineA series of operations that take the contents of a Scene, and displays them on a screen. Unity lets you choose from pre-built render pipelines, or write your own. More info
See in Glossary, where Unity evaluates the contribution of a probe for the whole object.
Each reflection probe has the Blend Distance property. This property is the distance from the face of a reflection box volume towards the center of the box volume.
Unity uses the Blend Distance property to determine the contribution of a reflection probe. When a pixel of an object is on the face of a reflection probe volume, that pixel gets 0% of reflections from the probe. When a pixel is inside the reflection probe volume and its distance from each face exceeds the Blend Distance value, the pixel gets 100% of reflections.
If the Blend Distance value is more than half of the distance between faces of the reflection probe volume, the reflection probe cannot provide 100% contribution to any pixel within the volume.
When a GameObject is within multiple reflection probe volumes, maximum two of the probes can affect the GameObject. Unity selects which probes affect the GameObject using the following criteria:
The Importance property of a reflection probe. Unity selects two probes with higher Importance values and ignores the others.
If the Importance values are the same, Unity selects probes which have the smallest box volumes.
If the Importance values and the box volumes are the same, Unity determines which two reflection probe volumes contain larger surface areas of a GameObject, and picks the probes of those volumes.
When two reflection probes affect a GameObject, for each pixel, Unity calculates the weight of each probe depending on the distance of this pixel from the faces of the probe box volumes and the values of the Blend Distance properties.
If the pixel is relatively close to faces of both box volumes and the sum of weights of both probes is less than 1, Unity assigns the remaining weight to the _GlossyEnvironmentCubeMap. This cube map contains the reflection from the lighting source set in the Lighting window under Environment Lighting > Source. In most cases this source is the skybox.
If the pixel is within both box volumes and farther than the Blend Distance values from faces of both volumes:
If the Importance properties of the reflection probes are the same, Unity blends reflections from the probes with equal weights.
If the Importance property of one of the probes is higher, Unity applies the reflections only from that probe.