This node is supported in HtoA but is an initial implementation and is not very user friendly. It lacks the viewport preview to move and control the blocker shape.
Light blockers give flexibility to the Lighting TD. They can be used as an artificial method of masking light in a scene without the overhead of adding additional geometry. Used carefully, they provide a degree of artistic freedom, allowing you to define the light boundaries in non physical ways.
The Light Blocker is a light filter that specifies a primitive volume defined in the Geometry Type (box, sphere, cylinder, or plane) which when connected to a light node will block or modify the light as it passes through that volume. The blocker will only influence a light it is connected to, just like other filters (i.e. the geometry affects nothing else, including GI, and is invisible). One, simplistic use would be to mimic the effect of a complex lamp housing, (possibly in combination with the barndoor filter) without modeling the lamp geometry. Another use would be to create shadows in your scene that look different to how they normally would.
You can also have multiple light blockers on the same light.
See the Light Filters page for more information on how to create and connect the Light Blocker filter.
Determines the shape of the blocked light. A light blocker can be a box, cylinder, sphere, or plane.
Box. Rollover image for GUI (Maya).
Cylinder. Rollover image for GUI (Maya).
Sphere. Rollover image for GUI (Maya).
Plane. Rollover image for GUI (Maya).
A matrix for the light blocker shape with rotation, translation, scale and pivot settings.
This value is the strength of the light blocker effect. The light blocker will not be apparent unless the density value is above 0.
Increases the circular shape of plane light blockers.
Attenuates the edge of the height of the light blocker.
Attenuates the ramp based on the direction set.
This is the magnitude of the ramp multiplier, applying along the Ramp Axis direction. Negative values flip the Ramp Axis direction.