The described systems and methods are directed at interactively rendering
graphics using precomputed radiance transfer (PRT). A reflectance matrix
that represents the reflectance of a particular object to be rendered is
determined. Source lighting associated with the object is represented
using basis functions. The reflectance matrix is factored into view and
light components. A raw transfer matrix is determined based, in part,
from the factored reflectance matrix and the source lighting. The raw
transfer matrix is partitioned to obtain transfer matrices, which are
used to render the object. The described systems and methods are capable
of rendering glossy objects with well-defined shadows.