Anonymous user
Animate a pendulum: Difference between revisions
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end
end</lang>
=={{header|Scala}}==
Inspired by Java
<lang Scala>import scala.swing._
import scala.swing.Swing._
import scala.actors._
import scala.actors.Actor._
import java.awt.{Color, Graphics}
object Pendulum extends SimpleSwingApplication {
val length = 100
val prefSizeX = 2*length+50
val prefSizeY = length/2*3
lazy val ui = new Panel {
import math._
background = Color.white
preferredSize = (prefSizeX, prefSizeY)
peer.setDoubleBuffered(true)
var angle: Double = Pi/2;
def pendular = new Actor {
var angleAccel, angleVelocity = 0.0;
var dt = 0.1
def act() {
while (true) {
angleAccel = -9.81 / length * sin(angle)
angleVelocity += angleAccel * dt
angle += angleVelocity * dt
repaint()
Thread.sleep(15)
}
}
}
override def paintComponent(g: Graphics2D) = {
super.paintComponent(g)
g.setColor(Color.white);
g.fillRect(0, 0, size.width, size.height);
val anchorX = size.width / 2
val anchorY = size.height / 4
val ballX = anchorX + (sin(angle) * length).toInt
val ballY = anchorY + (cos(angle) * length).toInt
g.setColor(Color.lightGray)
g.drawLine(anchorX-2*length, anchorY, anchorX+2*length, anchorY)
g.setColor(Color.black)
g.drawLine(anchorX, anchorY, ballX, ballY)
g.fillOval(anchorX - 3, anchorY - 4, 7, 7)
g.drawOval(ballX - 7, ballY - 7, 14, 14)
g.setColor(Color.yellow)
g.fillOval(ballX - 7, ballY - 7, 14, 14)
}
}
def top = new MainFrame {
title = "Rosetta Code >>> Task: Animate a pendulum | Language: Scala"
contents = ui
ui.pendular.start
}
}</lang>
=={{header|Scheme}}==
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