1. A processing device for processing a plurality of polygon meshes that each approximate a three-dimensional object with use of polygonal shapes, wherein each polygon mesh includes a plurality of polygons and processes for each polygon mesh include a coordinate transformation and a gradient calculation, the coordinate transformation being for transforming (i) sets of local coordinates of a plurality of vertices of each polygon mesh into (ii) sets of world coordinates of the plurality of vertices of each polygon mesh in a world coordinate system, the gradient calculation being for calculating gradients of each polygon mesh based on the respective set of world coordinates, and the processing device comprises: a plurality of processors each having a computation unit that performs the coordinate transformation and the gradient calculation; a distribution unit operable to distribute the sets of local coordinates of the vertices of the polygon meshes to the computation units so that each set of the local coordinates is transformed by a different one of the computation units, and cause the computation units to perform the coordinate transformation; an allocation unit operable to allocate each of the polygons to a respective one of the computation units that is to perform the gradient calculation; and a supply unit operable to supply a set of world coordinates of each of the polygons to the respective one of the computation units allocated by the allocation unit.