The following light filters are available in MAXtoA:
Arnold "light filters" are arbitrary shaders that can modify a light's output based on distance, position, or other factors. This makes it easy to extend the built-in light sources with additional effects. There are 4 light filters:
Barndoors are opaque moving panels attached to the sides of the light's opening used for additional control over the shape of the light beam.
The gobo filter is used to break up the light beam into an irregular, more natural pattern such as tree leaves, etc.
The light_blocker filter will block out an arbitrary geometrically defined area of a connected light.
The light_decay filter specifies the attenuation ranges of where the light starts and ends.
Light Filter Modifiers
Light Filters are available in MAXtoA as Light Modifiers. They are available when an Arnold light is selected:
Modifiers give you the ability to copy and paste your Light Filter onto other lights, including instancing the modifiers to multiple lights. You can apply modifiers to Group objects containing lights by using Copy and Paste from a single light onto the Group object. The modifier is then instanced to all lights in the group, and controllable from the top-level group object. The four built-in light filters are included as separate modifiers: Decay, Barndoor, Light Blocker, and Gobo (also known as Projection). The fifth option, the 'Arnold Light Filter' modifier, allows you to place a custom light filter shader into the modifier:
Arnold Decay Filter Modifier added to Arnold Light