[Visualpython-users] [Q] Repeat the same vpython script?

[Young-Jin L. <yl...@ui...>]

Hi, I have a question how to repeat the same vpython scripts.
I was implementing physics simulation software with vpython and wxpython and
I wanted to repeat vpython simulation when a button is clicked. The
following is what I tried. This is not runnable because I was using
wxPython, not a Tkinter. But I don't think you would have problem
understanding my intention.

When I first clicked the "Start Simulation", it worked as I expected. But
when I closed the VPython window and clicked again the "Start Simulation", I
didn't see anything. But 'start simulation' and 'end simulation' debug
straings appeared in the command window.

Any ideas what I did wrong?

Thanks in advance.

Young-Jin Lee

# initial review of 1d free fall example

# Button ID
BT_START = 10

from wxPython.wx import *
from wxPython.html import wxHtmlWindow
from visual import *

class CPFreeFall1D_InitialPane( wxHtmlWindow ):
    def __init__( self, parent, id, **kwargs ):
        wxHtmlWindow.__init__( self, parent, id, **kwargs )
        wxButton( self, BT_START, "Start Simulation", wxPoint( 100, 100 ) )
        EVT_BUTTON( self, BT_START, self.OnClickStart )

    def OnClickStart( self, event ):
        # read the configuration file
        import ConfigParser
        cfg = ConfigParser.ConfigParser()
        cfg.read( 'freefall1d.cfg' )

        self.startSimulation( cfg )    # When "Start Simulation" button is
clicked, VPython simulatoin starts.

    def startSimulation( self, cfg ):    # Body of VPython simulation
        print 'start simulation'

        scene.width = scene.height = 500.
        scene.x = scene.y = 0
        scene.forward = ( -0.2, -0.5, -1 )
        scene.autoscale = 0
        scene.userzoom = 0
        scene.range = ( 15, 15, 15 )
        scene.exit = 0  # only close the simulation window

        # start an actual simulation
        scene.select()
        xmax = 10
        dx = xmax / 5
        grid = []
        gravity = cfg.get( 'Characteristics', 'gravity' )
        r = float( cfg.get( 'Characteristics', 'diameter' ) ) / 2

        for x in arange( -xmax, xmax+dx, dx ):
            grid.append( curve( pos = [(x, 0, -xmax), (x, 0, xmax)],
                                color = ( .7, .7, .7 ) ) )

        for z in arange( -xmax, xmax+dx, dx ):
            grid.append( curve( pos = [(-xmax, 0, z), (xmax, 0, z)],
                                color = (.7, .7, .7) ) )

        ball = sphere(pos=(0,8,0), radius=r, color=color.red)
        ball.selected = 0
        ball.velocity = vector(0,-1,0)
        dt = 0.1

        ballPosition = []
        ballVelocity = []
        t = []
        currentT = 0

        while ball.y > ball.radius:
            rate(10)
            ball.pos = ball.pos + ball.velocity*dt
            ball.velocity.y = ball.velocity.y - float(gravity)*dt
            wake = sphere( pos = ball.pos, radius = 0.1, color =
color.blue )
            t.append( currentT + dt )
            ballPosition.append( ball.pos.y )
            ballVelocity.append( ball.velocity.y )
            currentT = currentT + dt

        print 'end simulation'