Planar Reflection Probe

The Planar Reflection Probe component is one of the types of Reflection Probe that the High Definition Render Pipeline (HDRP) provides to help you create reactive and accurate reflective Materials.

Properties

Planar Reflection Probes share many properties with the the built-in render pipeline Reflection Probe, and the HDRP cubemap Reflection Probe.

Planar Reflection Probes use the same texture format than the one selected in HDRP Asset for Color Buffer Format.

General Properties

Property Description

Realtime Mode A Planar Reflection Probe updates in real time. Use this property to tell HDRP how often to update the Probe.
• Every Frame: Updates the Probe’s capture data every frame.
• On Enable: Updates the Probe’s capture data each time Unity calls the component’s OnEnable() function. This occurs whenever you enable the component in the Inspector or activate the GameObject that the component attaches to.
• On Demand: Updates the Probe's capture data when you request it. To do this, access the Probe's HDAdditionalReflectionData and call the RequestRenderNextUpdate() function.

Property	Description
Realtime Mode	A Planar Reflection Probe updates in real time. Use this property to tell HDRP how often to update the Probe. • Every Frame: Updates the Probe’s capture data every frame. • On Enable: Updates the Probe’s capture data each time Unity calls the component’s `OnEnable()` function. This occurs whenever you enable the component in the Inspector or activate the GameObject that the component attaches to. • On Demand: Updates the Probe's capture data when you request it. To do this, access the Probe's `HDAdditionalReflectionData` and call the `RequestRenderNextUpdate()` function.

Projection Settings

The following properties control the projection settings for this Planar Reflection Probe.

Property	Description
Proxy Volume	The Reflection Proxy Volume this Probe uses to correct displacement issues between the Probe’s capture point (Mirror Position) and the position of the reflective Material using the RenderTexture this Probe captures. Note: The Proxy Volume you assign must be the same Shape as the Influence Volume.
Use Influence Volume As Proxy Volume	Tick this checkbox to use the boundaries of the Influence Volume as the Proxy Volume. This property only appears when you have not set a Reflection Proxy Volume to the Proxy Volume property.

Influence Volume

The Influence Volume defines the area around the Probe in which reflective Materials use the results that the Probe captures to influence the reflective behavior of their surface. The Planar Reflection Probe also uses the bounds of the Influence Volume to calculate Field Of View if you don’t provide an override value.

For reflective objects not aligned with the planar probe direction, the reflection will smoothly fade out as the reflected rays leave the reflected camera field of view.

Property	Description
Shape	Defines the shape of the Influence Volume. The possible values are Box and Sphere. The availability of properties below depends on the selected shape.
Box Size	Defines the scale of each axis of the box that represents the Influence Volume. Only available with a Box Shape.
Radius	Defines the radius of the sphere that represents the Influence Volume. Only available with a Sphere Shape.
Per Axis Control	Enable the checkbox to control the Blend Distance per axis. Only available with a Box Shape.
Blend Distance	The inward distance from the Box Size or Radius at which this Planar Reflection Probe blends with other Reflection Probes. In Normal mode, this property is a single value that modulates the distance at which this Reflection Probe blends with other Reflection Probes in every direction. This mode is available for Box or Sphere Influence Volumes. For the Box shape, when Per Axis Control is enabled, this property uses six values, one for each side of the box. Use each of the six input fields to define the blend distance in each direction. For example, Y defines the blending distance for the face at the top of the box and -Y defines the blending distance for the face on the bottom. This mode is only available for Box Influence Volumes.This feature is only available for deferred Reflection Probes.

Capture Settings

The following properties control the method that the Planar Reflection Probe uses to capture the directional view of its surroundings.

Property	Description
Field Of View Mode	Defines the mode to use when computing the field of view.
Clear Mode	Defines how to fill empty background areas of the RenderTexture this Probe captures. • Sky uses the sky defined by the current Volume settings to fill empty background areas. • Color uses the Background Color setting to fill empty background areas. • None reuses the previous value for each pixel that doesn’t represent a reflected GameObject, instead of filling in empty areas of the RenderTexture.
Background Color	The color to fill empty background areas of the RenderTexture if you set the Clear Mode to Background.
Clear Depth	Choose whether the Planar Reflection Probe clears the Depth Buffer or not.
Volume Layer Mask	A LayerMask that defines which Volumes affect this Planar Reflection Probe’s capture.
Volume Anchor Override	Set the Transform that the Volume system uses to handle the position of this Planar Reflection Probe. For example, if you want this Planar Reflection Probe to match post-processing effects with the view Camera, set this property to the view Camera’s Transform. The Volume system then uses the Camera’s position to process which Volume affects this Planar Reflection Probe.
Use Occlusion Culling	Enables Occlusion Culling for this Planar Reflection Probe.
Culling Mask	A LayerMask that defines which Layers to include in the reflection. GameObjects on the Layers included in this LayerMask appear in the reflection.
Clipping Planes - Near	The closest point relative to the Planar Reflection Probe that the Probe captures reflections.
Clipping Planes - Far	The furthest point relative to the Planar Reflection Probe that it captures reflections.
Probe Layer Mask	Acts as a culling mask for environment lights (light from other Planar Reflection Probes and Reflection Probes). This Planar Reflection Probe ignores all Reflection Probes that are on Layers not included in this Layer mask, so use this property to ignore certain Reflection Probes when rendering this one.
Custom Frame Settings	Allows you to define custom Frame Settings for this Probe. Disable this property to use the Default Frame Settings in your Unity Project’s HDRP Asset.
Resolution	Set the resolution of this Planar Reflection Probe. Use the drop-down to select which quality mode to derive the resolution from. If you select Custom, set the resolution, measured in pixels, in the input field. A higher resolution increases the fidelity of planar reflection at the cost of GPU performance and memory usage, so if you experience any performance issues, try using a lower value.
Rough Reflections	Disable the checkbox to tell HDRP to use this Planar Reflection Probe as a mirror. If you do this, the receiving surface must be perfectly smooth or the reflection result is not accurate. If you want perfect reflection, disabling this option can be useful because it means HDRP does not need to process rough refraction and thus decreases the resource intensity of the effect.
Mirror Position	Offsets the position of the mirror from the Transform Position. This property only appears when you enable more options for this section.
Range Compression Factor	The factor which HDRP divides the result of the probe's rendering by. This is useful to deal with very bright or dark objects in the reflections that would otherwise be saturated. This property only appears when you enable more options for this section.

Render Settings

The following properties control extra behavior options for fine-tuning the behavior of your Planar Reflection Probes.

Property	Description
Light Layer	A mask that allows you to choose which Light Layers this Reflection Probe affects. This Reflection Probe only affects Mesh Renderers or Terrain with a matching Rendering Layer Mask. Navigate to your Project’s HDRP Asset > Render Pipeline Supported Features and enable Light Layers to use this property.
Multiplier	A multiplier that HDRP applies to the RenderTexture captured by the Planar Reflection Probe. Higher multiplier values make the queried RenderTexture brighter, and lower multiplier values make the queried RenderTexture darker.
Weight	The overall weight of this Reflection Probe’s contribution to the reflective effect of Materials. When Reflection Probe’s blend together, the weight of each Probe determines their contribution to a reflective Material in the blend area.
Fade Distance	The distance, in meters, from the camera at which reflections begin to smoothly fade out before they disappear completely.

Gizmos

You can use Scene view gizmos to visually customize specific properties.

Gizmo	Property	Description
	Influence Volume boundary	Provides Scene view handles that allow you to move the boundaries of the Influence Volume, which defines the area this Reflection Probe affects reflective Materials. Edits the Box Size or Radius value, depending on the Shape you select.
	Blend Distance boundary	Provides Scene view handles that allows you to alter the inward distance from the Box Size or Radius at which this Planar Reflection Probe blends with other Reflection Probes. For the Box shape, when Per Axis Control is enabled, there is a separate handle for each size of the box.
	Blend Normal Distance boundary	Provides Scene view handles that allow you to resize the boundary where pixels with a normal pointing away from the Capture Position don’t receive any influence from this Probe.
	Mirror Position	Changes the behavior of the Move Tool so that it alters the Mirror Position property, rather than the Position of the Transform.
	Mirror Rotation	Changes the behavior of the Rotate Tool so that it alters the Mirror Rotation property, rather than the Rotation of the Transform.
	Chrome Gizmo.	Displays a chrome quad to preview the probe's texture in the scene.

Best practices

If you use a Planar Reflection Probe as a mirror (i.e its influence volume overlap a GameObject with a Material that has its smoothness and metallic properties set to 1) it is best practice to disable the Rough Refraction property to decrease the resource intensity. If a receiving surface isn't a perfect mirror and the Rough Reflection option is disabled, the surface still renders smooth, but the result is physically incorrect.