89 lines
2.6 KiB
Plaintext
89 lines
2.6 KiB
Plaintext
#!/usr/bin/env rune
|
|
pragma.syntax("0.9")
|
|
|
|
def pi := (-1.0).acos()
|
|
def makeEPainter := <unsafe:com.zooko.tray.makeEPainter>
|
|
def makeLamportSlot := <import:org.erights.e.elib.slot.makeLamportSlot>
|
|
def whenever := <import:org.erights.e.elib.slot.whenever>
|
|
def colors := <import:java.awt.makeColor>
|
|
|
|
# --------------------------------------------------------------
|
|
# --- Definitions
|
|
|
|
def makePendulumSim(length_m :float64,
|
|
gravity_mps2 :float64,
|
|
initialAngle_rad :float64,
|
|
timestep_ms :int) {
|
|
var velocity := 0
|
|
def &angle := makeLamportSlot(initialAngle_rad)
|
|
def k := -gravity_mps2/length_m
|
|
def timestep_s := timestep_ms / 1000
|
|
def clock := timer.every(timestep_ms, fn _ {
|
|
def acceleration := k * angle.sin()
|
|
velocity += acceleration * timestep_s
|
|
angle += velocity * timestep_s
|
|
})
|
|
return [clock, &angle]
|
|
}
|
|
|
|
def makeDisplayComponent(&angle) {
|
|
def c
|
|
def updater := whenever([&angle], fn { c.repaint() })
|
|
|
|
bind c := makeEPainter(def paintCallback {
|
|
to paintComponent(g) {
|
|
try {
|
|
def originX := c.getWidth() // 2
|
|
def originY := c.getHeight() // 2
|
|
def pendRadius := (originX.min(originY) * 0.95).round()
|
|
def ballRadius := (originX.min(originY) * 0.04).round()
|
|
def ballX := (originX + angle.sin() * pendRadius).round()
|
|
def ballY := (originY + angle.cos() * pendRadius).round()
|
|
|
|
g.setColor(colors.getWhite())
|
|
g.fillRect(0, 0, c.getWidth(), c.getHeight())
|
|
g.setColor(colors.getBlack())
|
|
|
|
g.fillOval(originX - 2, originY - 2, 4, 4)
|
|
g.drawLine(originX, originY, ballX, ballY)
|
|
g.fillOval(ballX - ballRadius, ballY - ballRadius, ballRadius * 2, ballRadius * 2)
|
|
|
|
updater[] # provoke interest provided that we did get drawn (window not closed)
|
|
} catch p {
|
|
stderr.println(`In paint callback: $p${p.eStack()}`)
|
|
}
|
|
}
|
|
})
|
|
|
|
c.setPreferredSize(<awt:makeDimension>(300, 300))
|
|
return c
|
|
}
|
|
|
|
# --------------------------------------------------------------
|
|
# --- Application setup
|
|
|
|
def [clock, &angle] := makePendulumSim(1, 9.80665, pi*99/100, 10)
|
|
|
|
# Initialize AWT, move to AWT event thread
|
|
when (currentVat.morphInto("awt")) -> {
|
|
|
|
# Create the window
|
|
def frame := <unsafe:javax.swing.makeJFrame>("Pendulum")
|
|
frame.setContentPane(def display := makeDisplayComponent(&angle))
|
|
frame.addWindowListener(def mainWindowListener {
|
|
to windowClosing(_) {
|
|
clock.stop()
|
|
interp.continueAtTop()
|
|
}
|
|
match _ {}
|
|
})
|
|
frame.setLocation(50, 50)
|
|
frame.pack()
|
|
|
|
# Start and become visible
|
|
frame.show()
|
|
clock.start()
|
|
}
|
|
|
|
interp.blockAtTop()
|