Patent ID: 6590582
Filing Date: 2003-07-08
Classification: G06T

Abstract:
A 3D graphics processing system capable of determining a position at which a polygon to be clipped is situated with respect to clipping planes constituting a viewing frustum, said viewing frustum having a vertex positioned relative to a viewer, to perform clipping processing, said system comprising a processor for executing instructions comprising:calculating a functional value at a center of a sphere circumscribed about said polygon from coordinate values of vertices of said polygon with respect to said clipping planes; calculating a radius of said sphere; comparing said functional value with said radius and with a negative value of said radius; if said functional value is less than said negative value of said radius, judging that said polygon is outside said viewing frustum; if said functional value is greater than said radius, judging that said polygon is inside said viewing frustum; if said functional value is not less than said negative value of said radius and if said functional value is not greater than said radius, judging that said polygon is on the boundary of said viewing frustum; and outputting a result of said judging as indicative of said position at which said polygon is situated with respect to said viewing frustum, whereby performing said clipping processing is based on said result.