Overview

Light definitions are passed to the Bake API by means of the .lights XML file. This file is the same format used for runtime lighting in GeoRadiosity, where each light has a few additional properties that apply only to the baking. The output from a given lights file goes into its own output directory, so it is possible to create multiple light configurations and switch between them without recalculating the scene. Multiple lighting configurations also share the precompute and other data, significantly reducing the time taken to generate baked output.

Lights properties

The .lights file has an XML schema available in the SDK (next to the ones for meshes, geometries and other properties). For each <light> element, there are a number of attributes, most of which are required (even if they are not applicable to the light type in question).

Parameter	Usage	Brief	Description
`name`	Required	The name of the light.	Unique light name.
`enabled`	Optional	Whether this light is enabled.	If not set, defaults to `true`
`type`	Required	An `Enlighten::eLightType` value.	`0` for spot; `1` for point; `2` for directional; `3` for rectangular.
`matrix`	Required	Position and direction of the light.
`colour`	Required	Normalised light colour.
`intensity`	Required	HDR colour strength.
`indirectColour`	Optional	Normalised light colour for indirect component.	If desired, the colour of the bounce light can be different to the direct colour. If not set, defaults to `colour`.
`indirectIntensity`	Optional	HDR colour strength.	If desired, the colour of the bounce light can be different to the direct colour. If not set, defaults to `intensity`.
`near`	Optional	Near plane. Used by spotlights and pointlights only.
`far`	Optional	Far plane. Used by spotlights and pointlights only. For area lights used only in baking.	Tiles that are farther away than this value are not added to `BakeVisibilityBuffer`: they are not lit in baked light, which speeds up the baking process. If `far` is set to `0`, the influence is infinity.
`intensityRadius`	Optional	The radius inside which intensity is clamped to the given value.	Specified in scene units. Unused for directional lights.
`epsilon`	Optional	Epsilon value used in the shadow map depth comparison.
`coneAngle`	Optional	The half radius of the spotlight.	A positive float.
`innerConeAngle`	Optional	The half radius of the spotlight's full brightness region.	A positive float.
`secondConeAngle`	Optional	The half angle in the secondary axis of a frustum or boxspot light (in radians).	A positive float.
`secondInnerConeAngle`	Optional	The half angle in the secondary axis of a frustum or boxspot light's full brightness region (in radians).	A positive float.
`falloffModel`	Optional	`default` (Inverse Squared) or `unreal` (Unreal Engine 3 compatible)
`exponent`	Optional	The falloff exponent of the light.	A positive float.
`radiosityMultiplier`	Optional	A value by which this light's radiosity will be multiplied.
`castsShadow`	Optional	Whether to cast shadows.	`true` or `false`
`shadowMapSize`	Optional	Resolution of the shadow map to use for this light. Only used in GeoViewer (not GeoRadiosity).	A positive integer.
`disableDirect`	Optional	Disable direct light contribution of this light for baking.	Boolean, (default `false`)
`generateLightMask`	Optional	Enable generation of light mask for light.	Boolean, (default `false`)
`shadowBias`	Optional	Shadow bias to offset the sample point in the direction to the light source for the shadow test.	Positive float
`pointRadius`	Optional	Defines the radius around a point light to which to compute visibility.	Used only for baking.
`directionalSpread`	Optional	Defines the radius around a directional light to which to compute visibility.
`rectangleHeight`	Optional	The height of a rectangular area light.	Defined in world units.
`rectangleWidth`	Optional	The width of a rectangular area light.	Defined in world units.
`lightUsage`	Optional	How this light will be used: `dynamic` or `baked`.
`animDuration`	Optional	Defines animation duration. Used only in GeoRadiosity.

Environment block

The <environment> element contains all the attributes related to setting the environment. Please check the schema file for more details.

Within it you can set a global environment using the filename attribute. The environment file should be placed next to this XML file, the type of the file content (loaded and saved with the C++ LoadInterface<> call) is Enlighten::CpuEnvironment. You can get one of these objects directly from the High Level Runtime, or construct one yourself from the highest MIP level of your cubemap.

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