[英]Java 2D Rotation and Global Coordinates?
我正在做一個簡單的游戲,其中有一個朝着鼠標的對象(一個帶有矩形桶的正方形)。 旋轉部分效果很好,但是我希望對象在沿y軸按下按鈕時移動,但直接向上移動,而不是相對於其旋轉。 現在,當按下按鈕時,對象將朝其面對的方向向前移動。 無論對象處於哪個方向,如何將其直接沿y軸向上移動? 這是代碼:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class RotationTestMain extends JFrame implements MouseMotionListener, KeyListener{
public static final long serialVersionUID = 666L;
public static final int SIZE = 50;
double xComponent;
double yComponent;
Image dbImage;
Graphics dbg;
int x;
int y;
int centerX;
int centerY;
JPanel area;
public RotationTestMain(){
area = new JPanel();
area.addMouseMotionListener(this);
addKeyListener(this);
x = 487;
y = 359;
centerX = x + SIZE/2;
centerY = y + SIZE/2;
add(area);
setSize(1024,768);
setLocationRelativeTo(null);
setVisible(true);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
@Override
public void paint(Graphics g){
dbImage = createImage(getWidth(), getHeight());
dbg = dbImage.getGraphics();
Graphics2D g2d = (Graphics2D) dbg;
draw(g2d);
g.drawImage(dbImage, 0, 0, this);
}
public void draw(Graphics2D g2d){
g2d.setColor(Color.BLACK);
g2d.rotate(calculateRotation(), centerX, centerY);
g2d.fillRect(x, y, SIZE, SIZE);
g2d.fillRect(centerX-5,y-20,10,25);
repaint();
}
public double calculateRotation(){
double rot;
if(yComponent >= 0){
rot = 3 * Math.PI - Math.atan(xComponent/yComponent);
}else {
rot = 2 * Math.PI - Math.atan(xComponent/yComponent);
}
return rot;
}
public static void main(String[] args) {
new RotationTestMain();
}
@Override
public void mouseDragged(MouseEvent m) {
centerX = x + SIZE/2;
centerY = y + SIZE/2;
xComponent = m.getX() - centerX;
yComponent = m.getY() - centerY;
}
@Override
public void mouseMoved(MouseEvent m) {
centerX = x + SIZE/2;
centerY = y + SIZE/2;
xComponent = m.getX() - centerX;
yComponent = m.getY() - centerY;
}
@Override
public void keyPressed(KeyEvent arg0) {
//TODO FIX THE MOVING PROBLEM
this.y -= 3;
}
@Override
public void keyReleased(KeyEvent arg0) {
}
@Override
public void keyTyped(KeyEvent arg0) {
}
}
非常感謝你的幫助!!
我認為問題出在這行g2d.rotate(calculateRotation(),centerX,centerY);
您不是旋轉對象,而是整個g2d。 因此,x,y軸也旋轉,因為它們是g2d的一部分。
因此,當您執行此操作時。y-= 3; 您確實沿y軸移動,但是y軸已旋轉。
我建議找到一種旋轉對象而不是整個g2d的方法。
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