Spot Light

A Spot Light emits light from a single point in a cone shape in a specific direction. Spot Lights are useful for simulating light from objects such as lamp posts and flashlights. By changing the Inner Cone Angle and Outer Cone Angle you can modify the shape of the light.

Light Properties

Property	Description
Radius	Light range (in world units).
Source Radius	Light build source radius (in world units).
Fall Off Exponent	Controls the radial falloff of a light. Works only if option the Use Inverse Squared Falloff is disabled.
Use Inverse Squared Falloff	If checked, physically based inverse squared distance falloff will be used.
Color	Light emission color.
Brightness	Light brightness parameter. Controls intensity of the light emitted by this actor.
Inner Cone Angle	Light inner cone angle (in degrees).
Outer Cone Angle	Light outer cone angle (in degrees).
View Distance	Controls light visibility range. The distance at which the light becomes completely faded. Use a value of 0 to always draw a light.
Minimum Roughness	Controls the minimum roughness value used to clamp material surface roughness during shading. Can help with softening specular highlights.

Area Lights

By using the Source Radius property you can change the spot light source build dimensions. This allows simulating area lights and brings more realism into the scenes.

Light Fall Off

Flax offers two modes for light fall off. A custom Exponent parameter can be used or use the Inverse Squared Falloff mode. Inverse squared mode gives a more physically based distance falloff, where Radius is only clamping the light's contribution. Hovewer using the manual light falloff exponent gives more customization options.

Shadow Properties

Property	Description
Mode	Describes how a visual element casts shadows. Possible options: Option Description None Never render shadows. Static Only Render shadows only in static views (env probes, lightmaps, etc.). Dynamic Only Render shadows only in dynamic views (game, editor, etc.). All Always render shadows.
Sharpness	Controls shadows sharpness. Can be used to tweak the penumbra width.
Strength	Controls dynamic shadow blending strength. Default is 1 for fully opaque shadows, a value of 0 disables shadows.
Distance	Shadow rendering distance (in world units).
Fade Distance	Shadow fade off distance (in world units).
Depth Bias	Controls dynamic shadow depth bias value. Depth bias used for shadow map comparison.
Normal Offset Scale	Controls dynamic shadows normal vector offset scale. A factor specifying the offset to add to the calculated shadow map depth with respect to the surface normal.
Contact Shadows Length	The length of the rays for contact shadows computed via screen-space tracing. Set this to values higher than 0 to enable screen-space shadow rendering for this light. This improves the shadowing details. Actual ray distance is based on the pixel distance from the camera.
Update Rate	Frequency of shadow updates. 1 - every frame, 0.5 - every second frame, 0 - on start or change. It's the inverse value of how many frames should happen in-between shadow map updates (eg. inverse of 0.5 is 2 thus shadow will update every 2nd frame).
Update Rate At Distance	Frequency of shadow updates at the maximum distance from the view at which shadows are still rendered. This value is multiplied by Shadows Update Rate and allows scaling the update rate in-between the shadow range. For example, if light is near view, it will get normal shadow updates but will reduce this rate when far from view.
Resolution	Defines the resolution of the shadow map texture used to draw objects projection from light-point-of-view. Higher values increase shadow quality at cost of performance.

Note

To learn more about shadows in Flax see this page.

Volumetric Fog Properties

Property	Description
Scattering Intensity	Controls how much this light will contribute to the Volumetric Fog. When set to 0, there is no contribution.
Cast Shadow	If checked, light will cast a volumetric shadow to Volumetric Fog. Also shadow casting by this light should be enabled in order to make it cast volumetric fog shadows.

Note

To learn more about Volumetric Fog effect see this page.

IES Profile Properties

Property	Description
IES Texture	Assigned IES texture (light profiles from real world measured data). Learn more about it here.
Use IES Brightness	If checked, light brightness will be based on imported IES Profile brightness. Then use the Brightness Scale parameter to scale it.
Brightness Scale	Custom scale parameter for light brightness if the option Use IES Brightness is checked.

Note

To learn more about IES Light Profiles see this page.