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author | Martin v. Löwis <martin@v.loewis.de> | 2008-06-04 06:29:55 (GMT) |
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committer | Martin v. Löwis <martin@v.loewis.de> | 2008-06-04 06:29:55 (GMT) |
commit | 8718459f0f7f42f9fedf1f7525c52bd7ac16b51b (patch) | |
tree | 99aa2c451de1149763fee3b11906524d87a0ef5e /Demo/turtle/tdemo_planet_and_moon.py | |
parent | 4ed3ed13c5c82f4b46d633cb7f61d6218d6ed320 (diff) | |
download | cpython-8718459f0f7f42f9fedf1f7525c52bd7ac16b51b.zip cpython-8718459f0f7f42f9fedf1f7525c52bd7ac16b51b.tar.gz cpython-8718459f0f7f42f9fedf1f7525c52bd7ac16b51b.tar.bz2 |
Patch #1513695: New turtle module, with demos.
Diffstat (limited to 'Demo/turtle/tdemo_planet_and_moon.py')
-rw-r--r-- | Demo/turtle/tdemo_planet_and_moon.py | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/Demo/turtle/tdemo_planet_and_moon.py b/Demo/turtle/tdemo_planet_and_moon.py new file mode 100644 index 0000000..e3c87a0 --- /dev/null +++ b/Demo/turtle/tdemo_planet_and_moon.py @@ -0,0 +1,113 @@ +#!/usr/bin/python +""" turtle-example-suite: + + tdemo_planets_and_moon.py + +Gravitational system simulation using the +approximation method from Feynman-lectures, +p.9-8, using turtlegraphics. + +Example: heavy central body, light planet, +very light moon! +Planet has a circular orbit, moon a stable +orbit around the planet. + +You can hold the movement temporarily by pressing +the left mouse button with mouse over the +scrollbar of the canvas. + +""" +from turtle import Shape, Turtle, mainloop, Vec2D as Vec +from time import sleep + +G = 8 + +class GravSys(object): + def __init__(self): + self.planets = [] + self.t = 0 + self.dt = 0.01 + def init(self): + for p in self.planets: + p.init() + def start(self): + for i in range(10000): + self.t += self.dt + for p in self.planets: + p.step() + +class Star(Turtle): + def __init__(self, m, x, v, gravSys, shape): + Turtle.__init__(self, shape=shape) + self.penup() + self.m = m + self.setpos(x) + self.v = v + gravSys.planets.append(self) + self.gravSys = gravSys + self.resizemode("user") + self.pendown() + def init(self): + dt = self.gravSys.dt + self.a = self.acc() + self.v = self.v + 0.5*dt*self.a + def acc(self): + a = Vec(0,0) + for planet in self.gravSys.planets: + if planet != self: + v = planet.pos()-self.pos() + a += (G*planet.m/abs(v)**3)*v + return a + def step(self): + dt = self.gravSys.dt + self.setpos(self.pos() + dt*self.v) + if self.gravSys.planets.index(self) != 0: + self.setheading(self.towards(self.gravSys.planets[0])) + self.a = self.acc() + self.v = self.v + dt*self.a + +## create compound yellow/blue turtleshape for planets + +def main(): + s = Turtle() + s.reset() + s.tracer(0,0) + s.ht() + s.pu() + s.fd(6) + s.lt(90) + s.begin_poly() + s.circle(6, 180) + s.end_poly() + m1 = s.get_poly() + s.begin_poly() + s.circle(6,180) + s.end_poly() + m2 = s.get_poly() + + planetshape = Shape("compound") + planetshape.addcomponent(m1,"orange") + planetshape.addcomponent(m2,"blue") + s.getscreen().register_shape("planet", planetshape) + s.tracer(1,0) + + ## setup gravitational system + gs = GravSys() + sun = Star(1000000, Vec(0,0), Vec(0,-2.5), gs, "circle") + sun.color("yellow") + sun.shapesize(1.8) + sun.pu() + earth = Star(12500, Vec(210,0), Vec(0,195), gs, "planet") + earth.pencolor("green") + earth.shapesize(0.8) + moon = Star(1, Vec(220,0), Vec(0,295), gs, "planet") + moon.pencolor("blue") + moon.shapesize(0.5) + gs.init() + gs.start() + return "Done!" + +if __name__ == '__main__': + msg = main() + print msg + mainloop() |