Two light attributes,
clear_radius, define constraints on how shadows can be cast from the
associated light. Both of these attributes work in tandem to define the region where shadows cast by the light can appear.
Max Shadow Distance
Limits shadows cast by the associated light to max_shadow_distance away from the shadow caster. In the example below, the shadow’s distance from the shadow caster (the plane) ranges from 5.7 to 6.4.
Ignore shadows cast by the associated light until clear_radius distance is reached. We can think of this as the minimum distance away from the light that shadows can appear. In the example below, the shadow cast by the plane is between about 48 and 54 units from the light.
clear_radius should always be less than max_shadow_distance. If clear_radius overlaps max_shadow_distance, no shadows will appear. In the example below, you will see this behavior, as max_shadow_distance stays the same (at 6.1) and the clear_radius varies.