尽管 user2221343 已经回答了 Monkeybro10 的问题,但我认为在某些情况下可能会有所帮助,如果您使用他描述的技术,形状的轮廓可能会起作用:
例如,如果您绘制两个多边形,如果它们仅发生在多边形的确切轮廓上,则不会检测到它们的碰撞。仅当包含在多边形轮廓内的区域重叠时,才会检测到碰撞。如果填充两个多边形但不绘制它们,即使在可见区域的轮廓上也会检测到碰撞。
我写了一个小例子来说明我的意思。取消注释绘制或填充命令,并通过取消注释给定线将第二个多边形垂直上升一个像素。运行代码并在 JFrame 中观察结果。如果第二个多边形升起,并且两个多边形只能通过“填充”命令可见,则它们与其轮廓相交并检测到碰撞。如果第二个多边形没有上升,并且两个多边形都可以通过“draw”命令看到,它们与它们的轮廓相交,但不会检测到碰撞:
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Polygon;
import java.awt.geom.Area;
import javax.swing.JFrame;
public class Test {
private JFrame frame;
private Polygon polygon1;
private Polygon polygon2;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Test window = new Test();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public Test() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame(){
private static final long serialVersionUID = 1L;
@Override
public void paint(Graphics g){
super.paint(g);
doDrawing(g);
}
};
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
int nShape1 = 4;
int xPoly1[] = {30,50,50,30};
int yPoly1[] = {30,30,50,50};
polygon1 = new Polygon(xPoly1,yPoly1,nShape1);
int nShape2 = 4;
int xPoly2[] = {35,55,55,35};
int yPoly2[] = {50,50,70,70};
// uncomment next line to rise second polygon vertically by one pixel
//yPoly2[] = {49,49,69,69};
polygon2 = new Polygon(xPoly2,yPoly2,nShape2);
}
public synchronized void doDrawing(Graphics g){
g.setColor(new Color(255,0,0));
// if you draw the polygon, collision on the exact outline won't be detected.
// uncomment draw or fill command to see what I mean.
g.drawPolygon(polygon1);
g.fillPolygon(polygon1);
g.setColor(new Color(0,0,255));
// if you draw the polygon, collision on the exact outline won't be detected.
// uncomment draw or fill command to see what I mean.
g.drawPolygon(polygon2);
g.fillPolygon(polygon2);
Area area = new Area(polygon1);
area.intersect(new Area(polygon2));
if(!area.isEmpty()){
System.out.println("intersects: yes");
}
else{
System.out.println("intersects: no");
}
}
}