Original Publication Date: 1985-Mar-01
Included in the Prior Art Database: 2005-Feb-18
An area fill or shading mechanism marks areas of the display space intercepted by the boundary of an object to be filled in order to improve the performance of the fill mechanism. For an indirectly addressed display the areas to be marked are made the same size as the display cells and the marking codes are held in the attribute byte of the refresh buffer. The boundary pels for the object to be shaded are computed using a modified Bresenham vector generation algorithm which only generates pels when there is a transition to a new raster row on the screen. The pels, generated in this way, are inserted into the screen buffer for interpretation by the filling mechanism. The contour vectors for the object are drawn in clockwise or anticlockwise order.