Decompression of surface normals in three-dimensional graphics data

A method for rendering compressed 3-D geometry data, the method comprising:

• receiving a set of said compressed 3-D geometry data, wherein the set of compressed 3-D geometry data comprises compressed representations of normals, wherein the compressed representations of normals comprise index values;
• and
• decompressing the compressed 3-D geometry data by:
• accessing a table comprising a plurality of unit normals, wherein said plurality of unit normals are a particular representative subset of all possible unit normals,
• using each index value to select a particular unit normal from said table;
• adjusting said unit normal based on one or more bits of general direction information included with said index values;
• and
• using the selected normals to render an image specified by the decompressed 3-D geometry data.

A computer program embodied on a carrier medium, wherein the computer program comprises a plurality of instructions configured to:

• receive a set of compressed 3-D graphics data, wherein the set of compressed 3-D geometry data comprises compressed representations of normals, wherein the compressed representations of normals comprise index values;
• and
• decompress the compressed 3-D graphics data by:
• accessing a table comprising a plurality of directions, wherein said plurality of directions are a particular representative subset of all possible directions,
• using each index value to select a particular direction from said table, and
• using the selected directions to form normals;
• and
• use the selected normals to render an image specified by the decompressed 3-D graphics data.