| 摘要 |
PURPOSE:To form a thick line as a result by drawing a line segment in a more vertical width direction at every point in a length direction with the aid of a DDA when the respective points in the length direction based on the DDA (digital differential analyzer) algorithm of Bresenham. CONSTITUTION:At first, an error term for a length direction (lerr) and an error term for a width direction (werr) are prepared. The path of (b) in a figure is decided according to the code of the (lerr) and the path of (a) or (a') is decided according to the code of the (werr). Since the length direction is intersecting orthogonally with the width direction, the initial value of the error term, an increment when the error term is negative and an increment when the error term is positive are equally expressed by formula I for both of the error terms. Then, when the sequence of points are formed in the width direction and in an inverse order for satisfying a condition that the point is not pinned by an identical coordinate point, the identical path is needed to be traced inversely to the case of a correct order. For example, the path 11 in the figure is decided, the update of the error term there is expressed by formula II. |
