UE4 Directional Lights
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Unreal Engine 4.9
On this page:
- Directional Light Properties
The Directional Light simulates light that is being emitted from a source that is infinitely far away. This means that all shadows cast by this light will be parallel, making this the ideal choice for simulating sunlight. The Directional Light when placed can be set to one of three Mobilitysettings:
Static - (pictured left) which means that the light cannot be changed in game. This is the fastest method for rendering and allows for baked lighting.
Stationary - (also pictured left) which means the light will only have its shadowing and bounced lighting from static geometry baked by Lightmass, all other lighting will be dynamic. This setting also allows for the light to change color and intensity in game, but, it does not move and allows partial baked lighting.
Moveable - (pictured left) which means the light is totally dynamic and allows for dynamic shadowing. This is the slowest in terms of rendering but allows for the most flexibility during gameplay.
Below you will see a representation of sunlight being cast through an opening in a roof.
Directional Light
Directional Light Shadow Frustum
The left image shows just the light, the right image has its Shadow Frustum enabled in order to see that the Directional Light is casting parallel light rays.
Light Direction (pictured left) is indicated by an arrow that points in the direction the light will emit which is useful for placing and orientating your light as needed.
Directional Light Properties
The properties of a Directional Light are broken up into 5 categories: Light, Light Shafts, Lightmass, Light Function and Cascaded Shadow Maps:
Light
Property | Description | IntensityTotal energy that the light emits.Light ColorThe color that the light emits.Used As Atmosphere Sun LightUses this Directional Light to define the location of the sun in the sky.Affects WorldDisables the light completely. Cannot be set at run time. To disable a light's effect during runtime, change its Visibility property.Casts ShadowsIf the light casts shadows.Indirect Lighting IntensityScales the indirect lighting contribution from the light.Min RoughnessMin roughness effective for this light, used for softening specular highlights.Shadow BiasControls how accurate the shadows from this light are.Shadow Filter SharpenHow much to sharpen shadow filtering for this light.Cast Translucent ShadowsWhether this light is allowed to cast dynamic shadows through translucent objects.Affect Dynamic Indirect LightingWhether the light should be injected into the Light Propagation Volume.Cast Static ShadowsWhether this light casts static shadows.Cast Dynamic ShadowsWhether this light casts dynamic shadows.Affect Translucent LightingWhether the light affects translucency or not.Light Shafts
Property | Description | Enable Light Shaft OcclusionWhether to occlude fog and atmosphere inter scattering with the screen space blurred occlusion from this light.Occlusion Mask DarknessHow dark the occlusion masking is, a value of 1 is no darkening.Occlusion Depth RangeEverything close to the camera than this distance will occlude the light shafts.Enable Light Shaft BloomWhether to render light shaft bloom for this light.Bloom ScaleScales the additive bloom color.Bloom ThresholdScene color must be larger than this to create bloom in the light shafts.Bloom TintWhat color to tint the bloom coming from the light shafts.Light Shaft Override DirectionCan be used to make the light shafts come from somewhere other than the light's actually direction.Lightmass
Property | Description | Light Source AngleAngle that the directional light's emissive surface extends relative to a receiver, affects penumbra sizes.Indirect Lighting SaturationA value of 0 will completely desaturate this light in Lightmass, 1 will be unchanged.Shadow ExponentControls the falloff of shadow penumbras.Light Function
Property | Description | Light Function MaterialThe light function material to be applied to this light.Light Function ScaleScales the light function projection.Light Function Fade DistanceThe distance at which the light function should be completely faded to the value in Disabled Brightness.Disabled BrightnessBrightness factor applied to the light when the light function is specified but disabled, say from the property above: Light Function Fade Distance.Cascaded Shadow Maps
Property | Description | Dynamic Shadow Distance MovableLightHow far Cascaded Shadow Map dynamic shadows will cover for a movable light, measured from the camera.Dynamic Shadow Distance StationaryLightHow far Cascaded Shadow Map dynamic shadows will cover for a stationary light, measured from the camera.Num Dynamic Shadow CascadesNumber of cascades to split the view frustum into for the whole scene.Cascade Distribution ExponentControls whether the cascades are distributed closer to the camera (larget exponent) or further from the camera (smaller exponent).Cascade Transition FractionProportion of the fade region between cascades.Shadow Distance Fadeout FractionControls the size of the fade out region at the far extent of the dynamic shadow's influence.Use Inset Shadows for Movable Objects(Stationary lights only) Whether to use per-object inset shadows for movable components, even though cascaded shadow maps are enabled.Unreal Engine 4.9
On this page:
- Directional Light Properties
The Directional Light simulates light that is being emitted from a source that is infinitely far away. This means that all shadows cast by this light will be parallel, making this the ideal choice for simulating sunlight. The Directional Light when placed can be set to one of three Mobilitysettings:
Static - (pictured left) which means that the light cannot be changed in game. This is the fastest method for rendering and allows for baked lighting.
Stationary - (also pictured left) which means the light will only have its shadowing and bounced lighting from static geometry baked by Lightmass, all other lighting will be dynamic. This setting also allows for the light to change color and intensity in game, but, it does not move and allows partial baked lighting.
Moveable - (pictured left) which means the light is totally dynamic and allows for dynamic shadowing. This is the slowest in terms of rendering but allows for the most flexibility during gameplay.
Below you will see a representation of sunlight being cast through an opening in a roof.
Directional Light
Directional Light Shadow Frustum
The left image shows just the light, the right image has its Shadow Frustum enabled in order to see that the Directional Light is casting parallel light rays.
Light Direction (pictured left) is indicated by an arrow that points in the direction the light will emit which is useful for placing and orientating your light as needed.
Directional Light Properties
The properties of a Directional Light are broken up into 5 categories: Light, Light Shafts, Lightmass, Light Function and Cascaded Shadow Maps:
Light
Property | Description | IntensityTotal energy that the light emits.Light ColorThe color that the light emits.Used As Atmosphere Sun LightUses this Directional Light to define the location of the sun in the sky.Affects WorldDisables the light completely. Cannot be set at run time. To disable a light's effect during runtime, change its Visibility property.Casts ShadowsIf the light casts shadows.Indirect Lighting IntensityScales the indirect lighting contribution from the light.Min RoughnessMin roughness effective for this light, used for softening specular highlights.Shadow BiasControls how accurate the shadows from this light are.Shadow Filter SharpenHow much to sharpen shadow filtering for this light.Cast Translucent ShadowsWhether this light is allowed to cast dynamic shadows through translucent objects.Affect Dynamic Indirect LightingWhether the light should be injected into the Light Propagation Volume.Cast Static ShadowsWhether this light casts static shadows.Cast Dynamic ShadowsWhether this light casts dynamic shadows.Affect Translucent LightingWhether the light affects translucency or not.Light Shafts
Property | Description | Enable Light Shaft OcclusionWhether to occlude fog and atmosphere inter scattering with the screen space blurred occlusion from this light.Occlusion Mask DarknessHow dark the occlusion masking is, a value of 1 is no darkening.Occlusion Depth RangeEverything close to the camera than this distance will occlude the light shafts.Enable Light Shaft BloomWhether to render light shaft bloom for this light.Bloom ScaleScales the additive bloom color.Bloom ThresholdScene color must be larger than this to create bloom in the light shafts.Bloom TintWhat color to tint the bloom coming from the light shafts.Light Shaft Override DirectionCan be used to make the light shafts come from somewhere other than the light's actually direction.Lightmass
Property | Description | Light Source AngleAngle that the directional light's emissive surface extends relative to a receiver, affects penumbra sizes.Indirect Lighting SaturationA value of 0 will completely desaturate this light in Lightmass, 1 will be unchanged.Shadow ExponentControls the falloff of shadow penumbras.Light Function
Property | Description | Light Function MaterialThe light function material to be applied to this light.Light Function ScaleScales the light function projection.Light Function Fade DistanceThe distance at which the light function should be completely faded to the value in Disabled Brightness.Disabled BrightnessBrightness factor applied to the light when the light function is specified but disabled, say from the property above: Light Function Fade Distance.Cascaded Shadow Maps
Property | Description | Dynamic Shadow Distance MovableLightHow far Cascaded Shadow Map dynamic shadows will cover for a movable light, measured from the camera.Dynamic Shadow Distance StationaryLightHow far Cascaded Shadow Map dynamic shadows will cover for a stationary light, measured from the camera.Num Dynamic Shadow CascadesNumber of cascades to split the view frustum into for the whole scene.Cascade Distribution ExponentControls whether the cascades are distributed closer to the camera (larget exponent) or further from the camera (smaller exponent).Cascade Transition FractionProportion of the fade region between cascades.Shadow Distance Fadeout FractionControls the size of the fade out region at the far extent of the dynamic shadow's influence.Use Inset Shadows for Movable Objects(Stationary lights only) Whether to use per-object inset shadows for movable components, even though cascaded shadow maps are enabled. 0 0
