Some of the predominant geometry processing operations are listed below. The geometry processor takes the surviving polygons and performs a vector translation from the database origin to the viewpoint. For example, a particular vertex in the database is originally referenced by a vector from the database origin. After this step, the same vertex is referenced by a vector from the viewpoint. These are standard vector additions and subtractions.
Translation requires three floating point operations per vertex.
The U axis always represents the forward direction, the V axis always represents the rightward direction, and the W axis always represents the downward direction. Rotation requires on the order of 15 floating point operations per vertex. Perspective scaling is performed by dividing vectors in UVW coordinates by their U-range so farther objects appear smaller. The U values are retained for the per-vertex Z calculations for depth buffering, as well as to allow perspective interpolation of texture coordinates. Lighting Model Intrinsic parameters such as polygon vertex color and texture coordinates are usually assigned during database design.