Method and apparatus for volume rendering with multiple depth buffers

A method for rendering a three-dimensional volume onto a two-dimensional image plane partitions translucent portions of the volume as defined by polygons into layers. The layers are sorted in a front-to-back order. A near color buffer is set to a transparent color, and a near depth buffer is set to a near clip surface. Then, the layers are processed in the sorted order by initializing a far color buffer to a background color, initializing a far depth buffer to a far clip surface, drawing a current layer into the far color and depth buffers, and rendering the volume, from the near clip surface to the far clip surface, into the near color and depth buffers. After all of the layers have been processed the far color buffer is reinitialized to the background color, the far depth buffer is reinitialized to the far clip surface, and the volume, from the near clip surface to the far clip surface, is rendered into the near color and depth buffers.