带有变换矩阵的旋转多边形.身材正在变形

Question

我在Java中相对较新，我的任务是实现从随机点绘制的图形的旋转。实现必须通过"裸逻辑"来编写，因此在这种情况下，AffineTransform工具不是一个选项。我陷入了我想将形状转换为原点以进行旋转的时刻。我绞尽脑汁，上网冲浪，但无法成功解决问题。已经有一个主题存在类似的问题，它是关于矩形翻译的，所以它对我不起作用。也许有人可以帮助解决这个问题。

公共类框架扩展 JFrame {

private JButton polyBtn = new JButton("Draw/Redraw Poly");
private JButton rotationBtn = new JButton("Rotate");
private JSpinner polySpn = new JSpinner(new SpinnerNumberModel(3,3,10,1));
private JSpinner angleSpn = new JSpinner(new SpinnerNumberModel(0,0,360,1));
private JPanel panel = new JPanel();
private JPanel controlPanel = new JPanel();
private JLabel polyLbl = new JLabel("Choose number of corners");
private JLabel angleLbl = new JLabel("Choose angle of rotation");
private int cornerAmount , degree ;
private boolean figureIsDrawed = false;
Random r = new Random();
Polygon poly = new Polygon();
Polygon editedPoly = new Polygon();

public Frame() {
super("Rotate Object");
setBounds(100, 100, 500, 250);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container container = this.getContentPane();
container.setLayout(new BorderLayout());
setVisible(true);
setLocationRelativeTo(null);
setResizable(false);
polyBtn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
cornerAmount = (int) polySpn.getValue();
drawPoly(cornerAmount);
}});
rotationBtn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
degree = (int) angleSpn.getValue();
rotateShape(degree);
}});
panel.setPreferredSize(new Dimension(350,250));
panel.setBackground(Color.ORANGE);
panel.setBorder(BorderFactory.createLineBorder(Color.black,3));
controlPanel.setBorder(BorderFactory.createLineBorder(Color.BLUE, 2));
controlPanel.setLayout(new GridLayout(6,0,0,0));
polyLbl.setFont(polyLbl.getFont().deriveFont(10.0f));
angleLbl.setFont(angleLbl.getFont().deriveFont(10.0f));
controlPanel.add(polyLbl);
controlPanel.add(polySpn);
controlPanel.add(polyBtn);
controlPanel.add(angleLbl);
controlPanel.add(angleSpn);
controlPanel.add(rotationBtn);
container.add(controlPanel,BorderLayout.CENTER);
container.add(panel,BorderLayout.EAST);
}
private void drawPoly(int corners) {
Graphics g = panel.getGraphics();
int panelWidth = panel.getWidth();
int panelHeight = panel.getHeight();
if(figureIsDrawed) {
poly.reset();
repaint();
figureIsDrawed = false;
}else {
poly.addPoint(panelWidth/2, panelHeight/2);
System.out.println(poly.xpoints[0]);
System.out.println(poly.ypoints[0]);
for(int i = 0 ; i < corners-1 ; i++) {
poly.addPoint(r.nextInt(panelWidth), r.nextInt(panelHeight));               
}
g.drawPolygon(poly);
figureIsDrawed = true;
}
}
private void rotateShape(int degree) {
Graphics g = panel.getGraphics();
int[] xCord = poly.xpoints;
int[] yCord = poly.ypoints;
double rads = degree * (Math.PI/180);
double sin =  Math.sin(rads);
double cos =  Math.cos(rads);
double[][] transform = new double[3][3];
int panelW = this.getWidth();
int panelH = this.getHeight();
transform[0][0] = cos;
transform[0][1] = -sin;
transform[1][0] = sin;
transform[1][1] = cos;
double[] transformedX = new double[xCord.length];
double[] transformedY = new double[yCord.length];
int[] updatedX = new int[xCord.length];
int[] updatedY = new int[yCord.length];
for(int i = 0;i<updatedX.length;i++) {
updatedX[i] = xCord[i];
updatedY[i] = yCord[i];
transformedX[i] = Math.round(updatedX[i] * transform[0][0] + updatedY[i] * transform[0][1] + transform[0][2]);
transformedY[i] = Math.round( updatedX[i] * transform[1][0] + updatedY[i] * transform[1][1] + transform[1][2]);
updatedX[i] = (int)transformedX[i];
updatedY[i] = (int)transformedY[i];
}
g.setColor(Color.orange);
g.fillRect(0, 0, panelW, panelH);
g.setColor(Color.black);
g.drawPolygon(updatedX, updatedY, updatedX.length); 
}

}

主要问题在于"旋转形状"方法。我只是想不通，如何使其正常工作。

Answer 1

您的轮换代码是正确的。但是您尝试变换的点数多于面中的点数。内部xpoints和ypoints数组不一定完全填充。用poly.npoints替换所有出现的xCord.length和yCord.length，您就可以开始了。