本程序是用DDA算法实现直线的画出，即在一个坐标轴上以单位间隔对线段取样，从而确定另一个坐标轴上最靠近线路经的对应整数值。-This procedure is the DDA algorithm to draw a straight line, that is, axis in a unit interval on the line segment sampling, to determine the axis closest to another line by the correspondi