翻转旋转和图像

我正在用 Java 编写一个平台游戏，并且正在手动编码玩家动画。我分别为每个肢体设置动画，改变位置和旋转。当玩家面向右时，这工作得很好，但是当玩家面向左时，我不知道如何处理旋转，以使它们在玩家向左转时看起来相同。每个身体部位的位置都是相对于玩家的 x 和 y 值存储的，因此我确实需要一种水平翻转旋转的方法。我知道我解释得不是很好，但如果有人理解我想说的并且可以提供帮助，我将非常感激。先感谢您。 :)

所以基本的想法是简单地翻转/镜像Graphics通过将轴之一缩放负值（-1).

这可以通过简单地使用来完成Graphics#scale，例如，要水平翻转图形，您只需使用

graphics.scale(-1, 1);

您需要翻译Graphics通过可视区域的宽度以及使用Graphics#translate将图像重新定位在可视区域内。

此后绘制的所有内容都会受到更改的影响。因此，您应该拍摄快照Graphics每次重大更改之前的上下文，只需确保您dispose当你完成后...

这是一个（相当可悲的动画明智的）示例......基本上，当您按向左或向右箭头时，标志会翻转并重新绘制场景。根据标志的不同，Graphics上下文被翻转/镜像...

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class AnimateCharacter {

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

    public AnimateCharacter() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private BufferedImage body;
        private BufferedImage[] legs;

        private double[] angels;
        private double[] deltas;

        private Point[] pivots = new Point[]{
            // Foreground...
            new Point(100, 227), // Foreleg
            new Point(155, 201), // Hindleg
            // Background...
            new Point(93, 218), // Foreleg
            new Point(143, 195), // Hindleg
        };

        private Point[] locations = new Point[]{
            // Foreground...
            new Point(67, 221), // Foreleg
            new Point(124, 172), // Hindleg
            // Background...
            new Point(60, 219), // Foreleg
            new Point(112, 166), // Hindleg
        };

        private int direction = 1;

        public TestPane() {
            legs = new BufferedImage[4];
            angels = new double[]{
                45,
                40,
                -5,
                0
            };
            deltas = new double[]{
                -4,
                -4,
                4,
                4
            };
            try {
                body = ImageIO.read(getClass().getResource("/Body.png"));
                // Foreground...
                legs[0] = ImageIO.read(getClass().getResource("/ForeLeg.png"));
                legs[1] = ImageIO.read(getClass().getResource("/HindLeg.png"));
                // Background...
                legs[2] = ImageIO.read(getClass().getResource("/ForeLeg.png"));
                legs[3] = ImageIO.read(getClass().getResource("/HindLeg.png"));
            } catch (IOException exp) {
                exp.printStackTrace();
            }

            Timer timer = new Timer(40, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    for (int index = 0; index < angels.length; index++) {
                        angels[index] += deltas[index];
                        if (angels[index] < -45) {
                            angels[index] = -45;
                            deltas[index] *= -1;
                        } else if (angels[index] > 45) {
                            angels[index] = 45;
                            deltas[index] *= -1;
                        }
                    }
                    repaint();
                }
            });
            timer.start();

            InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
            ActionMap am = getActionMap();

            im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0), "left");
            im.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0), "right");

            am.put("left", new AbstractAction() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    direction = 1;
                    repaint();
                }
            });
            am.put("right", new AbstractAction() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    direction = -1;
                    repaint();
                }
            });
        }

        @Override
        public Dimension getPreferredSize() {
            return body == null ? new Dimension(200, 200) : new Dimension(body.getWidth() + 50, body.getHeight() + 50);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            applyQualityRenderingHints(g2d);

            int x = (getWidth() - body.getWidth()) / 2;
            int y = (getHeight() - body.getHeight()) / 2;

            if (direction < 0) {
                g2d.scale(-1, 1);
                g2d.translate(-getWidth(), 0);
            }

            // Background legs...
            drawLegs(g2d, x, y, 2);

            g2d.drawImage(body, x, y, this);

            // Foreground legs...
            drawLegs(g2d, x, y, 0);

            g2d.dispose();
        }

        protected void drawLegs(Graphics2D g2d, int x, int y, int offset) {

            for (int index = 0; index < 2; index++) {
                Graphics2D copy = (Graphics2D) g2d.create();
                copy.translate(x, y);
                int leg = index + offset;
                int pivotX = pivots[leg].x;
                int pivotY = pivots[leg].y;
                copy.rotate(Math.toRadians(angels[leg]), pivotX, pivotY);
                copy.drawImage(
                        legs[leg],
                        locations[leg].x,
                        locations[leg].y,
                        this);
                copy.dispose();
            }

        }

        public void applyQualityRenderingHints(Graphics2D g2d) {

            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);
//        g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);

        }
    }

}

魔法发生在几个地方......

The Graphics首先复制上下文，然后（如果需要）使用翻转scale...

protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2d = (Graphics2D) g.create();
    //...
    if (direction < 0) {
        g2d.scale(-1, 1);
        g2d.translate(-getWidth(), 0);
    }

我在画腿时也使用同样的技术......

protected void drawLegs(Graphics2D g2d, int x, int y, int offset) {

    for (int index = 0; index < 2; index++) {
        Graphics2D copy = (Graphics2D) g2d.create();
        copy.translate(x, y);
        //...
        copy.rotate(Math.toRadians(angels[leg]), pivotX, pivotY);
        copy.drawImage(
                legs[leg],
                locations[leg].x,
                locations[leg].y,
                this);
        copy.dispose();
    }

这隔离了对副本的更改Graphics在上下文中，每个副本都将继承其父级的当前状态，这使得这是一项非常有用的技术......