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Animate a pendulum: Difference between revisions
→Add Groovy
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=={{header|Groovy}}==
<lang groovy>
import java.awt.*;
import javax.swing.*;
class Pendulum extends JPanel implements Runnable {
private angle = Math.PI / 2;
private length;
Pendulum(length) {
this.length = length;
setDoubleBuffered(true);
}
@Override
void paint(Graphics g) {
g.setColor(Color.WHITE);
g.fillRect(0, 0, getWidth(), getHeight());
g.setColor(Color.BLACK);
int anchorX = getWidth() / 2, anchorY = getHeight() / 4;
def ballX = anchorX + (Math.sin(angle) * length) as int;
def ballY = anchorY + (Math.cos(angle) * length) as int;
g.drawLine(anchorX, anchorY, ballX, ballY);
g.fillOval(anchorX - 3, anchorY - 4, 7, 7);
g.fillOval(ballX - 7, ballY - 7, 14, 14);
}
void run() {
def angleAccel, angleVelocity = 0, dt = 0.1;
while (true) {
angleAccel = -9.81 / length * Math.sin(angle);
angleVelocity += angleAccel * dt;
angle += angleVelocity * dt;
repaint();
try { Thread.sleep(15); } catch (InterruptedException ex) {}
}
}
@Override
Dimension getPreferredSize() {
return new Dimension(2 * length + 50, (length / 2 * 3) as int);
}
static void main(String[] args) {
def f = new JFrame("Pendulum");
def p = new Pendulum(200);
f.add(p);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.pack();
f.setVisible(true);
new Thread(p).start();
}
}
</lang>
=={{header|Go}}==
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