Lume Beam

Category: Volume

Shader Family: Volume

Output: Color

Related mental ray shader: Beam

The Lume Beam shader creates quick-to-render atmospheric effects such as volumic light beams and halos from selected light sources in your scene. Rendering speed is achieved by eliminating shadow calculations, which means that when shadows are necessary, you are responsible for creating shadow-casting geometry for the beam's area of effect.

This shader prefers light sources with an origin, directional lights (such as infinite lights) do not work as well. Also, note that the Lume Beam shader ignores the attenuation properties of the light.

Lume Beam Options

Color	Sets the color of the virtual fog particles. The final color of the beam or halo is determined by both the color of the particles and the color of the lights themselves.
Fog Density	Adjust the "thickness" of the fog effect surrounding the light source. Larger values cause the effect to be bigger and brighter; smaller values cause the effect to be smaller and dimmer.

Lights

Creates a light list to specify which lights should produce the effect. For more information, see Using Light Lists [Direct Illumination].

Render Tree Usage

To create a beam effect

Get a polygon mesh cone, for example, and place it in your scene. The size and form of the geometry determines the form of the beam.
Assign a fully transparent surface material to the cone.
Get a light source (such as a Point light) and place it at the top of the cone. Make sure that the light source's selective property includes the cone object.
In the render tree, connect the Lume Beam shader to the Volume input port of the cone's material node.
In the Lume Beam property editor, do the following:
- Add the light source to the shader's Light List.
- Set the Color and Density options to tune the effect.

To create a halo effect

When you attach the Lume Beam shader to the scene (in the pass volume shader stack) the shader creates halos around the origin of point lights and spotlights. See Creating a Volume Effect in a Scene.

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