[英]Moving point along lines
我繪制一個形狀,看起來像字母“ Y”。 然后我在其底部畫一個小點。
假設形狀為3條線,如下所示:
我想沿着1號線,然后2號線,再沿着2號線,然后3號線,然后最后回到1號線的起點,移動這一點。
它以滑塊指定的速度移動。
到目前為止,這是我的代碼:
public class yyyyy extends JFrame{
private Komponent komponent;
private Timer timer;
private int tick = 0;
private int speed = 4;
private int x1 = 225, y1 = 300, y2 = 225, x3 = 150, y3 = 150, x4 = 300;
private int x = x1, y = y1;
class Komponent extends JComponent{
/**
*
*/
private static final long serialVersionUID = -4028514932033769012L;
@Override
protected void paintComponent(Graphics arg0) {
if(tick< y1-y2){
x = x1;
y = y1-tick;
}
else if(tick>y1-y2 && tick < 2*(y1-y2)){
x = x1-tick + (y1-y2);
y = y2-tick + (y1-y2);
}
else if(tick>2*(y1-y2) && tick < 3*(y1-y2)){
x = x3 + tick - 2*(y1-y2);
y = y3 + tick - 2*(y1-y2);
}
else if(tick>3*(y1-y2)&& tick < 4*(y1-y2)){
x = x1 + tick - 3*(y1-y2);
y = y2 - tick + 3*(y1-y2);
}
else if(tick>4*(y1-y2)&& tick < 5*(y1-y2)){
x = x4 - tick + 4*(y1-y2);
y = y3 + tick - 4*(y1-y2);
}
else{
x = x1;
y = y2 + tick - 5*(y1-y2);
}
arg0.setColor(Color.BLUE);
arg0.drawLine(x1, y1, x1, y2);
arg0.drawLine(x1,y2,x3,y3);
arg0.drawLine(x1, y2, x4, y3);
arg0.setColor(Color.RED);
arg0.fillOval(x-5, y-5, 10, 10);
super.paintComponent(arg0);
}
}
public yyyyy (String string){
super(string);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setBounds(100,100,550,550);
add(komponent=new Komponent());
JPanel panel = new JPanel();
add(panel, BorderLayout.SOUTH);
final JCheckBox cb = new JCheckBox("Animacja");
cb.addChangeListener(new ChangeListener() {
@Override
public void stateChanged(ChangeEvent e) {
if(cb.isSelected()){
timer.start();
}
else{
timer.stop();
}
}
});
panel.add(cb);
timer = new Timer(50, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
tick+=speed;
if(tick > 6*(y1 -y2)){
tick -= 6*(y1-y2);
}
if(tick < 0){
tick = 6*(y2-y1);
}
komponent.repaint();
}
});
final JSlider speedSlider = new JSlider(-30,30,speed);
panel.add(speedSlider);
speedSlider.addChangeListener(new ChangeListener() {
@Override
public void stateChanged(ChangeEvent e) {
speed = speedSlider.getValue();
komponent.repaint();
}
});
setLocationRelativeTo(null);
setVisible(true);
}
public static void main(String[] args){
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new yyyyy("wat");
}
});
}
}
現在我有兩個問題:1.是否正確定義了滴答聲重置? 我覺得它應該是2 *所有行的距離之和后變為0。 2.我用注釋標記的代碼部分。 如何檢查當前點的x和y值? 我嘗試通過線方程式執行該操作,但效果不佳(指向始終只是在窗口外拍攝)。
編輯:代碼已更新。
盡管評論中已經回答了該問題(盡管它主要是調試提示,盡管實際上不是答案...),但我還是建議您對此進行概括。
您可能應該使用一組固定的坐標手動為每個線段建模。 相反,您可以創建一個通用的“路徑”,應遵循該路徑。 路徑上的位置可以定義為0.0到1.0之間的值。
然后,將定時和插值分離,並且可以單獨處理定時本身。 然后,您甚至可以添加漂亮的動畫效果,例如,在某處添加Math.sin
並獲得有趣的緩入/緩出效果。
但是,這是一個MCVE,顯示了如何實現此類通用路徑跟隨器的示例。 僅通過更改main
方法中PathFollower
實例的創建,它就可以從跟隨Y
變為跟隨X
import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Path2D;
import java.awt.geom.Point2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class PathFollowerTest
{
public static void main(String[] args)
{
final PathFollower pathFollower = createPathFollowerY();
//final PathFollower pathFollower = createPathFollowerX();
SwingUtilities.invokeLater(new Runnable()
{
@Override
public void run()
{
createAndShowGUI(pathFollower);
}
});
}
private static PathFollower createPathFollowerY()
{
Point2D p0 = new Point2D.Double(225, 300);
Point2D p1 = new Point2D.Double(225, 225);
Point2D p2 = new Point2D.Double(150, 150);
Point2D p3 = new Point2D.Double(300, 150);
PathFollower pathFollower = new PathFollower();
pathFollower.addPoint(p0);
pathFollower.addPoint(p1);
pathFollower.addPoint(p2);
pathFollower.addPoint(p1);
pathFollower.addPoint(p3);
pathFollower.addPoint(p1);
pathFollower.addPoint(p0);
return pathFollower;
}
private static PathFollower createPathFollowerX()
{
Point2D p0 = new Point2D.Double(150, 300);
Point2D p1 = new Point2D.Double(225, 225);
Point2D p2 = new Point2D.Double(150, 150);
Point2D p3 = new Point2D.Double(300, 300);
Point2D p4 = new Point2D.Double(300, 150);
PathFollower pathFollower = new PathFollower();
pathFollower.addPoint(p0);
pathFollower.addPoint(p1);
pathFollower.addPoint(p2);
pathFollower.addPoint(p1);
pathFollower.addPoint(p4);
pathFollower.addPoint(p1);
pathFollower.addPoint(p3);
pathFollower.addPoint(p1);
pathFollower.addPoint(p0);
return pathFollower;
}
private static void createAndShowGUI(final PathFollower pathFollower)
{
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setBounds(100, 100, 550, 550);
f.getContentPane().setLayout(new BorderLayout());
PathFollowerPanel pathFollowerPanel =
new PathFollowerPanel(pathFollower);
f.getContentPane().add(pathFollowerPanel, BorderLayout.CENTER);
final PathFollowerController pathFollowerController =
new PathFollowerController(
pathFollower, pathFollowerPanel);
JPanel panel = new JPanel();
f.getContentPane().add(panel, BorderLayout.SOUTH);
final JCheckBox cb = new JCheckBox("Animacja");
cb.addChangeListener(new ChangeListener()
{
@Override
public void stateChanged(ChangeEvent e)
{
pathFollowerController.setRunning(cb.isSelected());
}
});
panel.add(cb);
final JSlider speedSlider = new JSlider(-30, 30, 0);
panel.add(speedSlider);
speedSlider.addChangeListener(new ChangeListener()
{
@Override
public void stateChanged(ChangeEvent e)
{
pathFollowerController.setSpeed(speedSlider.getValue());
}
});
f.setLocationRelativeTo(null);
f.setVisible(true);
}
}
class PathFollowerController
{
private int speed = 0;
private PathFollower pathFollower;
private PathFollowerPanel pathFollowerPanel;
private final Timer timer = new Timer(50, new ActionListener()
{
private double alpha = 0;
@Override
public void actionPerformed(ActionEvent e)
{
alpha += speed / 500.0;
alpha %= 1.0;
while (alpha < -1.0)
{
alpha += 1.0;
}
pathFollower.setAlpha(alpha < 0 ? -alpha : alpha);
pathFollowerPanel.repaint();
}
});
PathFollowerController(PathFollower pathFollower,
PathFollowerPanel pathFollowerPanel)
{
this.pathFollower = pathFollower;
this.pathFollowerPanel = pathFollowerPanel;
}
void setRunning(boolean running)
{
if (running)
{
timer.start();
}
else
{
timer.stop();
}
}
public void setSpeed(int speed)
{
this.speed = speed;
}
}
class PathFollower
{
private final List<Point2D> points;
private Shape path;
private double pathLength = -1;
private double alpha = 0;
PathFollower()
{
points = new ArrayList<Point2D>();
}
void addPoint(Point2D p)
{
points.add(new Point2D.Double(p.getX(), p.getY()));
path = null;
pathLength = -1;
}
void setAlpha(double alpha)
{
this.alpha = alpha;
}
Point2D getCurrentPoint()
{
return computePoint(alpha);
}
Shape getPath()
{
if (path == null)
{
path = createPath();
}
return path;
}
private Shape createPath()
{
Path2D path = new Path2D.Double();
for (int i = 0; i < points.size(); i++)
{
Point2D p = points.get(i);
double x = p.getX();
double y = p.getY();
if (i == 0)
{
path.moveTo(x, y);
}
else
{
path.lineTo(x, y);
}
}
return path;
}
private double computePathLength()
{
double pathLength = 0;
for (int i = 0; i < points.size() - 1; i++)
{
Point2D p0 = points.get(i);
Point2D p1 = points.get(i + 1);
pathLength += p0.distance(p1);
}
return pathLength;
}
private Point2D computePoint(double alpha)
{
if (pathLength < 0)
{
pathLength = computePathLength();
}
double alphaPosition = alpha * pathLength;
double accumulatedLength = 0;
for (int i = 0; i < points.size() - 1; i++)
{
Point2D p0 = points.get(i);
Point2D p1 = points.get(i + 1);
double distance = p0.distance(p1);
double nextLength = accumulatedLength + distance;
if (nextLength >= alphaPosition)
{
double localAlpha =
(alphaPosition - accumulatedLength) / distance;
double x = p0.getX() + localAlpha * (p1.getX() - p0.getX());
double y = p0.getY() + localAlpha * (p1.getY() - p0.getY());
return new Point2D.Double(x, y);
}
accumulatedLength = nextLength;
}
Point2D p = points.get(points.size() - 1);
return new Point2D.Double(p.getX(), p.getY());
}
}
class PathFollowerPanel extends JPanel
{
private final PathFollower pathFollower;
PathFollowerPanel(PathFollower pathFollower)
{
this.pathFollower = pathFollower;
}
@Override
protected void paintComponent(Graphics gr)
{
super.paintComponent(gr);
Graphics2D g = (Graphics2D) gr;
g.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g.setColor(Color.BLUE);
g.setStroke(new BasicStroke(3.0f));
g.draw(pathFollower.getPath());
g.setColor(Color.RED);
Point2D p = pathFollower.getCurrentPoint();
double r = 5;
g.fill(new Ellipse2D.Double(
p.getX() - r, p.getY() - r, r + r, r + r));
}
}
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