标签：java animation rotation transform

我试图让一系列矩形围绕它们各自的中心旋转并向右移动,但由于该平面包含所有矩形,所有矩形一致地围绕最新添加的矩形的中心旋转,而不是围绕它们各自的中心独立旋转.以下是代码：

主要方案：

import java.awt.Graphics2D;
import java.util.ArrayList;

public class Rectangles {

    public static final int SCREEN_WIDTH = 400;
    public static final int SCREEN_HEIGHT = 400;

    public static void main(String[] args) throws Exception {
        Rectangles game = new Rectangles();
        game.play();
    }

    public void play() {
        board.setupAndDisplay();
    }

    public Rectangles() {
        board = new Board(SCREEN_WIDTH, SCREEN_HEIGHT, this);
        rectangle_2 = new Rectangle_2();
        rectangles = new ArrayList<Rectangle_2>();
    }

    public void drawRectangles(Graphics2D g, float elapsedTime) {
        ticks++;
        if (ticks % 4000 == 0) {
            Rectangle_2 rectangle = new Rectangle_2();
            rectangles.add(rectangle);
        }
        rotateRectangles(g);
        drawRectangles(g);
        moveRectangles(elapsedTime);

        for (int i = 0; i < rectangles.size(); i++) {
            Rectangle_2 rectangle = rectangles.get(i);
            if (rectangle.getX() < -75) {
                rectangles.remove(i);
                i--;
            }
        }
    }

    public void drawRectangles(Graphics2D g) {
        for (Rectangle_2 rectangle: rectangles) {
            rectangle.drawRectangle(g);
        }
    }

    public void rotateRectangles(Graphics2D g) {
        for (Rectangle_2 rectangle: rectangles) {
            rectangle.rotateRectangle(g);
        }
    }

    public void moveRectangles(float elapsedTime) {
        for (Rectangle_2 rectangle: rectangles) {
            rectangle.move(10 * elapsedTime);
        }
    }

    private Board board;
    private Rectangle_2 rectangle_2;
    private int ticks = 0;
    private ArrayList<Rectangle_2> rectangles;
}

矩形类：

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;

public class Rectangle_2 {

    public Rectangle_2() {
        x = 0;
        y = 200;
        rectangle = new Rectangle((int) x, (int) y, 25, 25);
    }

    public void drawRectangle(Graphics2D g) {
        g.setColor(Color.red);
        g.draw(rectangle);
    }

    public void rotateRectangle(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;
        angle += 0.001;
        g2.rotate(angle, rectangle.getX() + rectangle.getWidth() / 2, rectangle.getY() + rectangle.getHeight() / 2);
        g2.setColor(Color.red);
    }

    public void move(float elapsedTime) {
        x = x + elapsedTime;
        rectangle.setLocation((int) x, (int) y);
    }

    public boolean collides(Rectangle r) {
        return r.intersects(rectangle);
    }

    @Override
    public String toString() {
        return "Pipe [x = " + x + ", y = " + y + ", rectangle = " + rectangle + "]";
    }

    public Rectangle getRectangle() {
        return rectangle;
    }

    public double getX() {
        return x;
    }

    private double x;
    private double y;
    private double angle = 0;
    private Rectangle rectangle;
}

动画发生的棋盘类：

import java.awt.*;
import javax.swing.*;

public class Board extends JPanel {

    private static final long serialVersionUID = 1L;

    public Board(int width_, int height_, Rectangles simulator_) {
        width = width_;
        height = height_;
        game = simulator_;
        lastTime = -1L;
    }

    public void setupAndDisplay() {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new JScrollPane(this));
        f.setSize(width, height);
        f.setLocation(200, 200);
        f.setVisible(true);
        this.setFocusable(true);
    }

    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        boolean first = (lastTime == -1L);
        long elapsedTime = System.nanoTime() - lastTime;
        lastTime = System.nanoTime();
        g.setColor(Color.white);
        g.fillRect(0, 0, width, height);
        g.setColor(Color.white);
        game.drawRectangles((Graphics2D) g, (first ? 0.0f : (float) elapsedTime / 1e9f));
        repaint();
    }

    private int width;
    private int height;
    private long lastTime;
    private Rectangles game;
}

请注意,由于实施了延迟,矩形需要几秒钟才能显示.谢谢 ：).

解决方法:

Graphics上下文是一个共享资源,也就是说,在单个绘制周期中,所有组件都获得相同的Graphics上下文.您对Graphics上下文所做的任何更改也会被维护(或者在相同转换的情况下复合).所以这意味着,每次调用Graphics#rotate时,实际上都会复合可能已在其上执行的任何先前旋转.

你需要以两种方式改变你的代码……

>您需要独立的更新周期,与油漆周期无关
>在应用任何转换之前,创建Graphics上下文的本地副本

例如…

矩形成为主要的驱动器/引擎.它负责管理实体并在每个周期更新它们.通常情况下,我会使用某种描述其他情况可能使用的功能的界面,但是你明白了

public class Rectangles {

    public static void main(String[] args) throws Exception {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }
                Rectangles game = new Rectangles();
                game.play();
            }
        });
    }

    public void play() {

        Board board = new Board(this);

        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(board);
        f.pack();
        f.setLocation(200, 200);
        f.setVisible(true);
        Timer timer = new Timer(40, new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                updateRectangles();
                board.repaint();
                lastTime = System.nanoTime();
            }
        });
        timer.start();
    }

    public Rectangles() {
        rectangle_2 = new Rectangle_2();
        rectangles = new ArrayList<Rectangle_2>();
    }

    protected void updateRectangles() {
        boolean first = (lastTime == -1L);
        double elapsedTime = System.nanoTime() - lastTime;
        elapsedTime = (first ? 0.0f : (float) elapsedTime / 1e9f);

        ticks++;
        if (ticks <= 1 || ticks % 100 == 0) {
            Rectangle_2 rectangle = new Rectangle_2();
            rectangles.add(rectangle);
        }

        rotateRectangles();
        moveRectangles(elapsedTime);


        for (int i = 0; i < rectangles.size(); i++) {
            Rectangle_2 rectangle = rectangles.get(i);
            if (rectangle.getX() < -75) {
                rectangles.remove(i);
                i--;
            }
        }
    }

    public void drawRectangles(Graphics2D g) {
        for (Rectangle_2 rectangle : rectangles) {
            rectangle.drawRectangle(g);
        }
    }

    protected void rotateRectangles() {
        for (Rectangle_2 rectangle : rectangles) {
            rectangle.rotateRectangle();
        }
    }

    protected void moveRectangles(double elapsedTime) {
        for (Rectangle_2 rectangle : rectangles) {
            rectangle.move(10 * elapsedTime);
        }
    }

    private long lastTime = -1L;
    private Rectangle_2 rectangle_2;
    private int ticks = 0;
    private ArrayList<Rectangle_2> rectangles;
}

Board变成了可以渲染实体的表面

public class Board extends JPanel {

    public Board(Rectangles engine) {
        game = engine;
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(400, 400);
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        game.drawRectangles((Graphics2D) g);
    }

    private Rectangles game;
}

而Rectangle_2是一个简单的信息容器,它知道在有机会时如何绘制自己.您将注意到移动和旋转方法只是更新状态,它们什么都不做.

drawRectangle首先创建提供的Graphics2D上下文的副本,然后应用它的更改并呈现矩形,完成后,它调用dispose来处理副本

public class Rectangle_2 {

    public Rectangle_2() {
        x = 0;
        y = 200;
        rectangle = new Rectangle((int) x, (int) y, 25, 25);
    }

    public void drawRectangle(Graphics2D g) {
        Graphics2D g2 = (Graphics2D) g.create();
        g2.rotate(angle, rectangle.getX() + rectangle.getWidth() / 2, rectangle.getY() + rectangle.getHeight() / 2);
        g2.setColor(Color.red);
        g2.draw(rectangle);
        g2.dispose();
    }

    public void rotateRectangle() {
        angle += 0.001;
    }

    public void move(double elapsedTime) {
        x = x + elapsedTime;
        rectangle.setLocation((int) x, (int) y);
    }

    public boolean collides(Rectangle r) {
        return r.intersects(rectangle);
    }

    @Override
    public String toString() {
        return "Pipe [x = " + x + ", y = " + y + ", rectangle = " + rectangle + "]";
    }

    public Rectangle getRectangle() {
        return rectangle;
    }

    public double getX() {
        return x;
    }

    private double x;
    private double y;
    private double angle = 0;
    private Rectangle rectangle;
}

标签：java,animation,rotation,transform
来源： https://codeday.me/bug/20191003/1846501.html

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