{{tag>graphic skin texture emission}}
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[[:start|Start Page]] >> [[:gamedev|Game Development with the Drag[en]gine]] >> [[gamedev:skinproperties|Skin Texture Properties]] >> [[gamedev:texturepropertylist|Texture Property Database]] >> **emissivity.intensity**
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====== Skin Texture Property: emissivity.intensity ======

Defines the intensity of emitted light.

|Excepted Data Source|1 component value|
|Data Range|greater than or equal to 0|
|Default Value|1|
|Affected Modules|Graphic|
|Linked Properties|[[gamedev:textureproperties:emissivity|emissivity]]|

====== Description ======

The **emissivity.intensity** texture property is linked with the **[[gamedev:textureproperties:emissivity|emissivity]]** texture property. It defines the intensity of the emitted light. The **[[gamedev:textureproperties:emissivity|emissivity]]** texture property defines the color of the emitted light. The final emitted color is thus the **[[gamedev:textureproperties:emissivity|emissivity]]** texture property mulitplied component wise with this texture property. The intensity could also be stored directly into the **[[gamedev:textureproperties:emissivity|emissivity]]** texture property using a high definition range image. Using this texture property though the intensity can be modified at run-time using **[[gamedev:renderables|renderables]]**. Switching emitting light on and off without changing the skin on an object is a typical use of this texture property.

The intensity value relates to real world light intensities not in a 1-to-1 scale but more in a rescale scale mapping a wel lit room to the value 1 for convenience. An intensity value of 1 thus equals roughly a 100W light bulb or a well lit room at night. 10 equals roughly an overcast day outside. 20 equals roughly a full bright sunny day out in plain sun. 

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An interesting use for this texture property is to enable and disable or vary the light emission of a material. For this use a **[[gamedev:renderables|renderable]]** with a name like "**intensity**". Using a dynamic skin in the game scripts you can then alter the intensity of the emitted light to simulate all kinds of light animations like switching it on and off, flickering or temporarily dimmed lights as seen in gas light bulbs with a defunct starter.
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The source is typically a renderable or a single component value greater than or equal to 0.

The default value for this texture property is 1 which equals roughly a 100W light bulb or a well lit room.

====== Examples ======

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{{ :gamedev:textureproperties:emissivity.png |Vending machine at day and night with automatic lights due to the emissivity texture property}}
<WRAP centeralign>Vending machine at day and night with automatic lights due to the **emissivity** texture property. There is no need to enable or disable lights using game scripts. **[[gamedev:pbr|Physically Based Rendering]]** takes care of letting your materials emit light if it is dark. The **emissivity** texture property is set to a color image resembling the **[[gamedev:textureproperties:color|color]]** texture property with a constant **[[gamedev:textureproperties:emissivity_intensity|emissivity.intensity]]** for the entire material.</WRAP>
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{{ :gamedev:textureproperties:emissivity_intensity.png |Traffic light with 3 different emissivity.intensity renderables set to different values}}
<WRAP centeralign>Traffic light with 3 different **emissivity.intensity** **[[gamedev:renderables|renderables]]** set to different values. The red light is set to a bright intensity keeping up with the sunny day light. The yellow light in the middle is set to 0 intensity literally switching it off. And the green light is set to a low intensity resulting in a bareily visible green light against the sun light to show the dimmed light case. All this can be dynamically modified without switching materials.</WRAP>
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