Polygon drawing and filling apparatus which initially sorts three dimensional polygons by planar characteristics

A polygon drawing apparatus for admitting a figure drawing command including command type data and vertex data defining a polygon to be drawn and for outputting raster data about said polygon, said polygon drawing apparatus comprising:

• polygon shape analyzing means for judging, based on said command type data of said figure drawing command, whether said polygon constituted by said vertex data of said figure drawing command is a plane figure or a non-planar figure;
• division-into-triangle processing means for dividing said polygon into a plurality of triangles when said polygon shape analyzing means judges that said polygon is a non-planar figure and for generating vertex data about each of the divided triangles;
• triangle vertex data processing means for performing vertex data processing on each of said divided triangles constituted by said vertex data generated by said division-into-triangle processing means;
• polygon vertex data processing means for performing the vertex data processing on said polygon when said polygon shape analyzing means judges that said polygon is a plane figure;
• triangle forming means for dividing into a plurality of triangles the polygon constituted by the vertex data processed by said polygon vertex data processing means and for generating vertex data about each of the divided triangles;
• and
• triangle drawing means for successively transforming into raster data each of the triangles constituted by one of two kinds of vertex data, one kind of vertex data having been processed by said triangle vertex data processing means, the other kind of vertex data having been generated by said triangle forming means.