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10.5 PointLight

A PointLight is a light that shines from a given point within the 3D scene. Although the light source itself is invisible, the effects of the light vary with distance and orientation of the surface upon which it falls. A PointLight is computationally more expensive than a DirectionalLight because each object in the scene must have both orientation and distance relative to the light evaluated.


A PointLight contains attenuation properties that define how the brightness falls off with distance. The attenuation contains three components:


Constant—Subtracted from the intensity of the light irrespective of distance. That is, dimming the light at its source.

Linear—Subtracted for every unit moved away from the light source. The light at 2 meters is twice as

bright as the light at 4 meters.

Quadratic—Subtracted as a function of a square of the distance from the light. The light at 2 meters is four times as bright as the light at 4 meters.



 

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