DDA.rar_DDA_dda java_java d

package algorithm; import java.awt.Point; /** * * @author Zhong Jiawu * @version 1.0 */ public class BresenhamArc extends Algorithm { private int R = -1; private Point O = new Point(); private int start_degree = -1; private int stop_degree = -1; private Point start_point = new Point(); private Point stop_point = new Point(); private int start_quandrant = Quandrant.NE; private int stop_quandrant = Quandrant.NW; private int dD; private int cur_quandrant = Quandrant.NE; private int cur_xSign = 1; private int cur_ySign = 1; private Point cur_point = new Point(); private Point cur_begin_point = new Point(); private Point cur_end_point = new Point(); private static class Direction { public static final int H = 0; public static final int D = 1; public static final int V = 2; } private static class Quandrant { public static final int NE = 0; public static final int NW = 1; public static final int SW = 2; public static final int SE = 3; public static int getXSign(int q) { q %= 4; if (q == SE || q == NE) return 1; else return -1; } public static int getYSign(int q) { q %= 4; if (q == NE || q == NW) return 1; else return -1; } public static int next(int q) { return (q + 1); } public static int getQuandrant(int degree) { if (degree >= 0 && degree <= 90) return Quandrant.NE; else if (degree >= 90 && degree <= 180) return Quandrant.NW; else if (degree >= 180 && degree <= 270) return Quandrant.SW; else return Quandrant.SE; } public static boolean isClockwise(int q) { q = q % 4; if (q == NE || q == SW) return true; else return false; } public static boolean equals(int q1, int q2) { q1 %= 4; q2 %= 4; return q1 == q2; } } public BresenhamArc() { super(); } public void begin() { R = (int) point1.distance(point2); O = point1; start_quandrant = Quandrant.getQuandrant(start_degree); start_point.x = (int) Math.abs((double) R * Math.cos(Math.PI / 180 * start_degree)); start_point.y = (int) Math.abs((double) R * Math.sin(Math.PI / 180 * start_degree)); stop_quandrant = Quandrant.getQuandrant(stop_degree); stop_quandrant = start_degree <= stop_degree ? stop_quandrant : stop_quandrant + 4; stop_point.x = (int) Math.abs((double) R * Math.cos(Math.PI / 180 * stop_degree)); stop_point.y = (int) Math.abs((double) R * Math.sin(Math.PI / 180 * stop_degree)); cur_quandrant = start_quandrant; cur_xSign = Quandrant.getXSign(cur_quandrant); cur_ySign = Quandrant.getYSign(cur_quandrant); if (Quandrant.equals(cur_quandrant, stop_quandrant) && start_degree < stop_degree) { if (Quandrant.isClockwise(cur_quandrant)) { cur_begin_point = stop_point; cur_end_point = start_point; } else { cur_begin_point = start_point; cur_end_point = stop_point; } } else { if (start_point.equals(stop_point)) { cur_begin_point = start_point; cur_end_point = stop_point; } else if (Quandrant.isClockwise(cur_quandrant)) { cur_begin_point = new Point(0, R); cur_end_point = start_point; } else { cur_begin_point = start_point; cur_end_point = new Point(R, 0); } } cur_point = cur_begin_point; dD = cur_point.x * 2 - cur_point.y * 2 + 2; return; } public void gotoNextQuandrant() { cur_quandrant = Quandrant.next(cur_quandrant); cur_xSign = Quandrant.getXSign(cur_quandrant); cur_ySign = Quandrant.getYSign(cur_quandrant); if (Quandrant.equals(cur_quandrant, stop_quandrant)) { if (Quandrant.isClockwise(cur_quandrant)) { cur_begin_point = stop_point; cur_end_point = new Point(R, 0); } else { cur_begin_point = new Point(0, R); cur_end_point = stop_point; } } else { cur_begin_point = new Point(0, R); cur_end_point = new Point(R, 0); } cur_point = cur_begin_point; dD = cur_point.x * 2 - cur_point.y * 2 + 2; } public boolean hasNext() { if (cur_point.y >= cur_end_point.y) { return true; } else { if (cur_quandrant == stop_quandrant) { return false; } else { gotoNextQuandrant(); return true; } } } public Point next() { int direction; if (dD > 0) { int dDV = 2 * (dD - cur_point.x) - 1; if (dDV <= 0) { direction = Direction.D; } else { direction = Direction.V; } } else if (dD < 0) { int dHD = 2 * (dD + cur_point.y) - 1; if (dHD <= 0) { direction = Direction.H; } else { direction = Direction.D; } } else { direction = Direction.D; } switch (direction) { case Direction.D: { cur_point.x++; cur_point.y--; dD += 2 * cur_point.x - 2 * cur_point.y + 2; break; } case Direction.H: { cur_point.x++; dD += 2 * cur_point.x + 1; break; } case Direction.V: { cur_point.y--; dD += -2 * cur_point.y + 1; break; } } Point point = new Point(this.O); point.x += cur_point.x * cur_xSign; point.y += cur_point.y * cur_ySign; return point; } /** * @param start_degree * the start_degree to set */ public void setStart(int start_degree) { this.start_degree = start_degree; } /** * @param stop_degree * the stop_degree to set */ public void setStop(int stop_degree) { this.stop_degree = stop_degree; } }