在Java中旋转多边形
我正在编写的程序在屏幕上绘制多个星星，并为它们提供随机的方向和速度。 星星会从面板的边缘反弹并留在里面。 我需要让星星在移动时旋转。 我尝试了很多东西，我无法弄明白。 下面是我用来绘制星星并移动它们的代码。
附加信息：
– 星星在一个名为“星星”的集合中
– 我写了两个类，“Star”和“MyJPanel”
设点:(星级）
for (double current = 0; current < nPoints; current += 1) { i = (int)current; int[] X = new int[nPoints * 2]; int[] Y = new int[nPoints * 2]; cosX = -(Math.cos(current*((2*Math.PI)/(nPoints)))*radius[i % 2]); sinY = -(Math.sin(current*((2*Math.PI)/(nPoints)))*radius[i % 2]); X[i] = (int) cosX+x; Y[i] = (int) sinY+y; addPoint(X[i], Y[i]); } 移动方法:(在星级）
public void move(int width, int height) { if (location.x = width - radius[0]) { xIncr = -xIncr; } if (location.y = height - radius[0]) { yIncr = -yIncr; } translate(xIncr, yIncr); location.setLocation(location.x + xIncr, location.y + yIncr); xInc = xIncr; }
画星星:(在MyJPanel类中）
public void paintComponent(Graphics g) { super.paintComponent(g); for(int i = 0; i < stars.size(); i++) { g2d = (Graphics2D) g; g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, stars.get(i).getAlpha())); g2d.setColor(stars.get(i).getColor()); g2d.fillPolygon(stars.get(i)); if(stars.get(i).alpha == 0) { stars.remove(stars.indexOf(stars.get(i))); } } }
如果需要更多代码或信息，请告诉我，谢谢！
我将介绍使用几何和变换形状，文本和图像
基本上，我已经创建了一个自定义Path2D形状，代表了我的开始。 该类带有一些附加信息，包括它的x / y偏移和旋转。 然后它提供了一个辅助方法，用于根据这些属性创建此形状的变换实例，例如……
public Shape getTransformedInstance() { AffineTransform at = new AffineTransform(); Rectangle bounds = getBounds(); at.rotate(Math.toRadians(angle), x + (bounds.width / 2), y + (bounds.height / 2)); at.translate(x, y); return createTransformedShape(at); }
基本上，这就是魔术发生的地方。
有一个简单的摆动Timer ，它将三角形应用于位置和旋转。
import java.awt.Color; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Rectangle; import java.awt.RenderingHints; import java.awt.Shape; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.geom.AffineTransform; import java.awt.geom.Path2D; import java.util.Random; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.Timer; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException; public class RotateShape { public static void main(String[] args) { new RotateShape(); } public RotateShape() { EventQueue.invokeLater(new Runnable() { @Override public void run() { try { UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { ex.printStackTrace(); } JFrame frame = new JFrame("Testing"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.add(new TestPane()); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } }); } public class TestPane extends JPanel { private Star star; private double rotationDelta = 5d; private int xDelta = 0; private int yDelta = 0; public TestPane() { star = new Star(50, 50); star.moveLocatioBy(75, 75); Random rnd = new Random(); xDelta = rnd.nextInt(4) + 1; yDelta = rnd.nextInt(4) + 1; Timer timer = new Timer(40, new ActionListener() { @Override public void actionPerformed(ActionEvent e) { star.moveLocatioBy(xDelta, yDelta); Rectangle bounds = star.getBounds(); int x = star.getX(); int y = star.getY(); boolean bounced = false; if (x < 0) { x = 0; xDelta *= -1; bounced = true; } else if (x + bounds.width > getWidth()) { x = getWidth() - bounds.width; xDelta *= -1; bounced = true; } if (y < 0) { y = 0; yDelta *= -1; bounced = true; } else if (y + bounds.height > getHeight()) { y = getHeight() - bounds.height; yDelta *= -1; bounced = true; } if (bounced) { rotationDelta *= -1; } star.rotateByDegrees(rotationDelta); star.setLocation(x, y); repaint(); } }); timer.start(); } @Override public Dimension getPreferredSize() { return new Dimension(200, 200); } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g.create(); g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY); g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY); g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE); g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON); g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR); g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY); g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE); Shape shape = star.getTransformedInstance(); g2d.setColor(Color.BLUE); g2d.fill(shape); g2d.setColor(Color.RED); g2d.draw(shape); g2d.dispose(); } } public class Star extends Path2D.Double { private double angle = 0; private int x = 0, y = 0; public Star(int width, int height) { double heightPart = height / 3d; double widthPart = width / 3d; moveTo(width / 2, 0); lineTo(widthPart * 2, heightPart); lineTo(width, heightPart); lineTo(widthPart * 2, height / 2); lineTo(width, height); lineTo(width / 2, heightPart * 2); lineTo(0, height); lineTo(widthPart, height / 2); lineTo(0, heightPart); lineTo(widthPart, heightPart); closePath(); } public double getAngle() { return angle; } public int getX() { return x; } public int getY() { return y; } public void moveLocatioBy(int xDelta, int yDelta) { this.x += xDelta; this.y += yDelta; } public void rotateByDegrees(double delta) { angle += delta; } public void setLocation(int x, int y) { this.x = x; this.y = y; } public Shape getTransformedInstance() { AffineTransform at = new AffineTransform(); Rectangle bounds = getBounds(); at.rotate(Math.toRadians(angle), x + (bounds.width / 2), y + (bounds.height / 2)); at.translate(x, y); return createTransformedShape(at); } } }
扩展这个想法并不需要太多，所以每个开始都有它自己的delta值和简单的update方法（它传递了Container的宽度/高度），所以你可以制作很多-o-stars