Soft shadows can be rendered using a relatively expensive blur process by leveraging the structure provided for various user interfaces. The elements of a user interface may be arranged according to a hierarchical tree or scene graph. Certain related elements may be grouped into a shadow group that can cast and/or receive a shadow. When the root of the shadow group is designated, the other child elements of the group can be added automatically, up to the boundary of another shadow group. A single texture for a shadow group can be determined, blurred, and projected onto a corresponding receiving group. If the shadow needs to be regenerated due to motion, for example, only a single texture needs to be regenerated for the group instead of a shadow for each element. A throttling value may be set to further limit the number of shadows that can be regenerated per frame.