如何在給定的角度旋轉多邊形

Question

我創建一個指南針，這是一個JPanel繪製。我將座標系的中心翻譯爲JPanel的中心。現在我想在這個點上旋轉一個給定的角度，該角度來自程序的另一部分。我嘗試了AffineTransform，但我不明白如何正確使用它。當我嘗試時，針被塗在圓圈外面。

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.Font; 
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.Point; 
import java.awt.RenderingHints; 
import java.awt.Toolkit; 
import java.awt.geom.AffineTransform; 

import javax.swing.JFrame; 
import javax.swing.JPanel; 

public class TestFrame extends JFrame { 

    public TestFrame() { 
     initComponents(); 
    } 

    public void initComponents() { 
     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     setLocation(new Point((int) (Toolkit.getDefaultToolkit().getScreenSize().width/2) - 400, (int) (Toolkit 
       .getDefaultToolkit().getScreenSize().height/2) - 250)); 
     setSize(500, 500); 
     setVisible(true); 

     CompassPanel c = new CompassPanel(); 
     add(c, BorderLayout.CENTER); 

    } 

    public class CompassPanel extends JPanel { 

     private int circleX, circleY, circleRadius; 
     private int[] xPoints, yPoints; 

     public CompassPanel() { 
      setVisible(true); 
     } 

     @Override 
     public void paint(Graphics g) { 
      super.paint(g); 
      Graphics2D g2d = (Graphics2D) g; 

      AffineTransform a = new AffineTransform(); 
      a.translate(getWidth()/2.0, getHeight()/2.0); 
      g2d.transform(a); 
      g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); 
      circleRadius = (int) (getWidth() * 0.7); 
      circleX = (int) (-circleRadius * 0.5); 
      circleY = (int) (-circleRadius * 0.5); 

      g2d.setColor(Color.BLACK); 
      for (int angle = -45; angle <= 315; angle += 5) { 
       double sin = Math.sin(Math.toRadians(angle)); 
       double cos = Math.cos(Math.toRadians(angle)); 
       int x1 = (int) ((circleX + circleRadius/2) - cos * (circleRadius * 0.37) - sin 
         * (circleRadius * 0.37)); 
       int y1 = (int) ((circleY + circleRadius/2) + sin * (circleRadius * 0.37) - cos 
         * (circleRadius * 0.37)); 
       g.setColor(Color.BLACK); 
       g.drawLine(x1, y1, (circleX + circleRadius/2), (circleY + circleRadius/2)); 
      } 

      g2d.setFont(new Font("Arial", Font.BOLD, 11)); 
      g2d.drawString("WEST", circleX - 40, circleY + circleRadius/2 + 4); 
      g2d.drawString("EAST", circleX + circleRadius + 13, circleY + circleRadius/2 + 4); 
      g2d.drawString("NORTH", circleX + circleRadius/2 - 14, circleY - 15); 
      g2d.drawString("SOUTH", circleX + circleRadius/2 - 14, circleY + circleRadius + 25); 
      g2d.setColor(Color.WHITE); 
      g2d.fillOval(circleX, circleY, circleRadius, circleRadius); 
      g2d.setColor(Color.BLACK); 
      g2d.drawOval(circleX, circleY, circleRadius, circleRadius); 

      xPoints = new int[] { (int) (circleX + circleRadius/2), (int) (circleX + circleRadius * 0.25), 
        (int) (circleX + circleRadius/2), (int) (circleX + circleRadius * 0.75) }; 
      yPoints = new int[] { (int) (circleY + 30), (int) (circleY + circleRadius * 0.85), 
        (int) (circleY + circleRadius * 0.6), (int) (circleY + circleRadius * 0.85) }; 

      g2d.setColor(Color.RED); 
      g2d.fillPolygon(xPoints, yPoints, 4); 
      g2d.setColor(Color.black); 
      g2d.drawPolygon(xPoints, yPoints, 4); 

      g2d.setColor(Color.GREEN); 
      g2d.fillOval(-3, -3, 6, 6); 

     } 
    } 

    public static void main(String[] args) { 
     new TestFrame(); 
    } 
} 

Answer 1

我在你的代碼做了一些修改，增加了一些功能的旋轉，但是不能完全工作狀態，並只給你的是一個暗示它會如何工作。 代碼試圖從0變更至angle 30它將工作，但不完全好運:)

package com.src; 

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.Font; 
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.Point; 
import java.awt.Polygon; 
import java.awt.RenderingHints; 
import java.awt.Toolkit; 
import java.awt.geom.AffineTransform; 

import javax.swing.JFrame; 
import javax.swing.JPanel; 
import javax.vecmath.Matrix3d; 

public class TestFrame extends JFrame { 

    /** 
    * 
    */ 
    private static final long serialVersionUID = 1L; 

    public TestFrame() { 
     initComponents(); 
    } 

    public void initComponents() { 
     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     setLocation(new Point((int) (Toolkit.getDefaultToolkit().getScreenSize().width/2) - 400, (int) (Toolkit.getDefaultToolkit().getScreenSize().height/2) - 250)); 
     setSize(500, 500); 
     setVisible(true); 

     CompassPanel c = new CompassPanel(); 
     add(c, BorderLayout.CENTER); 

    } 

    public class CompassPanel extends JPanel { 

     /** 
     * 
     */ 
     private static final long serialVersionUID = 1L; 
     private int circleX, circleY, circleRadius; 
     private int[] xPoints, yPoints; 

     public CompassPanel() { 
      setVisible(true); 
     } 

     @Override 
     public void paint(Graphics g) { 
      super.paint(g); 
      Graphics2D g2d = (Graphics2D) g; 

      AffineTransform a = new AffineTransform(); 
      a.translate(getWidth()/2.0, getHeight()/2.0); 
      g2d.transform(a); 
      g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); 
      circleRadius = (int) (getWidth() * 0.7); 
      circleX = (int) (-circleRadius * 0.5); 
      circleY = (int) (-circleRadius * 0.5); 

      g2d.setColor(Color.BLACK); 
      for (int angle = -45; angle <= 315; angle += 5) { 
       double sin = Math.sin(Math.toRadians(angle)); 
       double cos = Math.cos(Math.toRadians(angle)); 
       int x1 = (int) ((circleX + circleRadius/2) - cos * (circleRadius * 0.37) - sin * (circleRadius * 0.37)); 
       int y1 = (int) ((circleY + circleRadius/2) + sin * (circleRadius * 0.37) - cos * (circleRadius * 0.37)); 
       g.setColor(Color.BLACK); 
       g.drawLine(x1, y1, (circleX + circleRadius/2), (circleY + circleRadius/2)); 
      } 

      g2d.setFont(new Font("Arial", Font.BOLD, 11)); 
      g2d.drawString("WEST", circleX - 40, circleY + circleRadius/2 + 4); 
      g2d.drawString("EAST", circleX + circleRadius + 13, circleY + circleRadius/2 + 4); 
      g2d.drawString("NORTH", circleX + circleRadius/2 - 14, circleY - 15); 
      g2d.drawString("SOUTH", circleX + circleRadius/2 - 14, circleY + circleRadius + 25); 
      g2d.setColor(Color.WHITE); 
      g2d.fillOval(circleX, circleY, circleRadius, circleRadius); 
      g2d.setColor(Color.BLACK); 
      g2d.drawOval(circleX, circleY, circleRadius, circleRadius); 

      xPoints = new int[] { (int) (circleX + circleRadius/2), (int) (circleX + circleRadius * 0.25), (int) (circleX + circleRadius/2), (int) (circleX + circleRadius * 0.75) }; 
      yPoints = new int[] { (int) (circleY + 30), (int) (circleY + circleRadius * 0.85), (int) (circleY + circleRadius * 0.6), (int) (circleY + circleRadius * 0.85) }; 
      int angle =30; 
      xPoints = rotateXPoints(xPoints, yPoints, angle); 
      yPoints = rotateYPoints(xPoints, yPoints, angle); 

      g2d.setColor(Color.RED); 
      g2d.fillPolygon(xPoints, yPoints, 4); 
      g2d.setColor(Color.black); 
      Polygon p = new Polygon(xPoints, yPoints, 4); 

      // g2d.drawPolygon(xPoints, yPoints, 4); 
      g2d.draw(p); 

      g2d.setColor(Color.GREEN); 
      g2d.fillOval(-3, -3, 6, 6); 

     } 
     public int[] rotateXPoints(int[] xPoints,int[] yPoints,int angle) { 
      for (int i = 0; i < xPoints.length; i++) { 
       Point p = new Point(xPoints[i], yPoints[i]); 
       p = rotatePoint(p, new Point(0, 0), angle); 
       xPoints[i] = p.x; 
      } 
      return xPoints; 

     } 
     public int[] rotateYPoints(int[] xPoints,int[] yPoints,int angle) { 
      for (int i = 0; i < yPoints.length; i++) { 
       Point p = new Point(xPoints[i], yPoints[i]); 
       p = rotatePoint(p, new Point(0, 0), angle); 
       yPoints[i] = p.y; 
      } 
      return yPoints; 

     } 
     public Point rotatePoint(Point pt, Point center, double angle) 
     { 
      angle = ((angle/180)*Math.PI); 
      double cosAngle = Math.cos(angle); 
      double sinAngle = Math.sin(angle); 

      pt.x = center.x + (int) ((pt.x-center.x)*cosAngle-(pt.y-center.y)*sinAngle); 
      pt.y = center.y + (int) ((pt.x-center.x)*sinAngle+(pt.y-center.y)*cosAngle); 
      return pt; 
     } 
    } 


    public static void main(String[] args) { 
     new TestFrame(); 
    } 
}