Patent ID: 6753861
Filing Date: 2004-06-22
Classification: G06T

Abstract:
A method for selecting a screen region on a screen of a monitor of a computer graphics display system to activate in rendering a straight line segment, the method comprising the steps of:aligning a rectangular grid to screen region boundaries, wherein the screen comprises a screen space divided into at least one screen region: locating a first and second endpoints of the straight line segment on the screen space, wherein a locus of the straight line segment is specified by equation A*x+B*y+C=0, wherein A, B, and C are respectively a first, second, and third constants, wherein x and y are respectively Cartesian coordinate system x-axis and y-axis values; defining a rectangular bounding box in the screen space having vertices at the first and second endpoints; identifying each screen region that at least partially overlaps the bounding box; and selecting each identified screen region through which the straight line segment passes to activate for rendering the straight line segment on the screen, wherein the step of selecting each overlapping screen region through which the straight line segment passes further comprises the steps of: successively selecting once each corner of the overlapping screen region until the overlapping screen region is marked as selected: evaluating expression A*x+B*y+C at the selected corner, storing in a memory the algebraic sign of the evaluated expression for the selected corner, and if the algebraic sign of the evaluated expression for the selected corner differs from any of the stored algebraic signs, marking the screen region as selected.