1. A computer implemented method of proximity detection comprising: defining a set of three dimensional entities in a screen-graph for analysis; for each entity in said defined set, creating a bounding box; setting said created bounding box to a first predetermined value; for each of said set created bounding boxes, performing an intersection test with at least one other bounding box; in the event that an intersection is found by said performed intersection test, for each face of each entity in the intersection enlarging the face by a second predetermined value; for each of said enlarged faces, performing an intersection test with each of said other enlarged faces; and in the event that an intersection is found by said performed intersection test of said enlarged faces, marking a collision.