Area lights geometries
Area lights geometries
Embedded Files
Unity lights of type “Area” emit light across a rectangle or a disc (1). In Predictive Engine, an area light can emit from any geometry (2).
To define an area light that emits light from a custom geometry, you must :
Convert it to an area light : right-click on the GameObject in the Hierarchy, menu "PredictiveSuite/Engine/Light/Physical Light/Convert Geometry To Area Light" : this will add a "Light" component of type "Area" and an Light Settings component to the geometry,
Define the area light by editing the Light Settings component.
Additional settings are available for the area light geometries :
Submesh selection
Submesh selection
Geometries can be complex and have several submeshes. If you define an area light on a geometry that has several submeshes, an additional Submesh field will be available on the UVR Light Settings component to let you choose wich submesh should be emitting light.
Emission direction
Emission direction
Up direction
Up direction
Area lights have a Light Up Direction field that defines whether the light should be oriented by the local tangent space of the geometry (figure A, example A) or the geometry’s global up (Z-)axis (figure B, example B).
By default, area lights with an intensity of type Measured Display should use the local tangent space of the geometry, and all other lights should use the geometry's global up axis.
https://en.wikipedia.org/wiki/Normal_(geometry)
Area light defined in Unity, Z axis pointing towards the blue arrow
Same area light, light up direction is Local : the light emits along the local normals of the sphere.
Same area light, light up direction is Axis Z : the light emits along the geometry Z axis.
Double sided geometries
Double sided geometries
When you define a uniform area light, you can choose if the light should be emitted from both sides of the geometry surface or not (see example bellow).
If the light has an UVR Light Settings component and its intensity is "Uniform", the "Emit on both sides" toggle enables you to choose how the light is emitted. Other intensity types (other than "Uniform") do not require this setting as the emission direction is already defined in the intensity definition.
If the light does not have an UVR Light Settings component, the emission direction can be defined in the PredictiveSuite preferences : see section bellow.
Area light defined in Unity, pointing towards the blue arrow
Same area light, Emit on both sides = False
Same area light, Emit on both sides = True
Default settings
Default settings
When you only define a light using the Unity Light component, a default geometry is used in Predictive Engine based on the Unity settings. By default, the area light in Predictive Engien will emit light from a transparent geometry in the direction defined by the Unity light. You can edit these default settings in the PredictiveSuite preferences, section Default Settings.
The "Emit on both sides" option defines whether the light is emitted from both sides of the geometry or only in the direction defined by the Unity light,
The "Default Material" is the material used on the geometry in Predictive Engine.
Area light in Unity, pointing towards the blue arrow
Same area light in Predictive Engine:
material = transparent,
emit both sides = false
Same area light in Predictive Engine:
material = black,
emit both sides = false
Same area light in Predictive Engine:
material = white,
emit both sides = false
Same area light in Predictive Engine:
material = white,
emit both sides = true
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