This commit is contained in:
Ingy döt Net 2013-04-10 21:29:02 -07:00
parent 764da6cbbb
commit db842d013d
19005 changed files with 197040 additions and 7 deletions

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USING: accessors alarms arrays calendar colors.constants kernel
locals math math.constants math.functions math.rectangles
math.vectors opengl sequences system ui ui.gadgets ui.render ;
IN: pendulum
CONSTANT: g 9.81
CONSTANT: l 20
CONSTANT: theta0 0.5
: current-time ( -- time ) nano-count -9 10^ * ;
: T0 ( -- T0 ) 2 pi l g / sqrt * * ;
: omega0 ( -- omega0 ) 2 pi * T0 / ;
: theta ( -- theta ) current-time omega0 * cos theta0 * ;
: relative-xy ( theta l -- xy )
[ [ sin ] [ cos ] bi ]
[ [ * ] curry ] bi* bi@ 2array ;
: theta-to-xy ( origin theta l -- xy ) relative-xy v+ ;
TUPLE: pendulum-gadget < gadget alarm ;
: O ( gadget -- origin ) rect-bounds [ drop ] [ first 2 / ] bi* 0 2array ;
: window-l ( gadget -- l ) rect-bounds [ drop ] [ second ] bi* ;
: gadget-xy ( gadget -- xy ) [ O ] [ drop theta ] [ window-l ] tri theta-to-xy ;
M: pendulum-gadget draw-gadget*
COLOR: black gl-color
[ O ] [ gadget-xy ] bi gl-line ;
M:: pendulum-gadget graft* ( gadget -- )
[ gadget relayout-1 ]
20 milliseconds every gadget (>>alarm) ;
M: pendulum-gadget ungraft* alarm>> cancel-alarm ;
: <pendulum-gadget> ( -- gadget )
pendulum-gadget new
{ 500 500 } >>pref-dim ;
: pendulum-main ( -- )
[ <pendulum-gadget> "pendulum" open-window ] with-ui ;
MAIN: pendulum-main

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REAL :: msec=10, Lrod=1, dBob=0.03, g=9.81, Theta(2), dTheta(2)
BobMargins = ALIAS(ls, rs, ts, bs) ! box margins to draw the bob
Theta = (1, 0) ! initial angle and velocity
start_t = TIME()
DO i = 1, 1E100 ! "forever"
end_t = TIME() ! to integrate in real-time sections:
DIFFEQ(Callback="pendulum", T=end_t, Y=Theta, DY=dTheta, T0=start_t)
xBob = (SIN(Theta(1)) + 1) / 2
yBob = COS(Theta(1)) - dBob
! create or clear window and draw pendulum bob at (xBob, yBob):
WINDOW(WIN=wh, LeftSpace=0, RightSpace=0, TopSpace=0, BottomSpace=0, Up=999)
BobMargins = (xBob-dBob, 1-xBob-dBob, yBob-dBob, 1-yBob-dBob)
WINDOW(WIN=wh, LeftSpace=ls, RightSpace=rs, TopSpace=ts, BottomSpace=bs)
WRITE(WIN=wh, DeCoRation='EL=4, BC=4') ! flooded red ellipse as bob
! draw the rod hanging from the center of the window:
WINDOW(WIN=wh, LeftSpace=0.5, TopSpace=0, RightSpace=rs+dBob)
WRITE(WIN=wh, DeCoRation='LI=0 0; 1 1, FC=4.02') ! red pendulum rod
SYSTEM(WAIT=msec)
start_t = end_t
ENDDO
END
SUBROUTINE pendulum ! Theta" = - (g/Lrod) * SIN(Theta)
dTheta(1) = Theta(2) ! Theta' = Theta(2) substitution
dTheta(2) = -g/Lrod*SIN(Theta(1)) ! Theta" = Theta(2)' = -g/Lrod*SIN(Theta(1))
END

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import gui
$include "guih.icn"
# some constants to define the display and pendulum
$define HEIGHT 400
$define WIDTH 500
$define STRING_LENGTH 200
$define HOME_X 250
$define HOME_Y 21
$define SIZE 30
$define START_ANGLE 80
class WindowApp : Dialog ()
# draw the pendulum on given context_window, at position (x,y)
method draw_pendulum (x, y)
# reference to current screen area to draw on
cw := Clone(self.cwin)
# clear screen
WAttrib (cw, "bg=grey")
EraseRectangle (cw, 0, 0, WIDTH, HEIGHT)
# draw the display
WAttrib (cw, "fg=dark gray")
DrawLine (cw, 10, 20, WIDTH-20, 20)
WAttrib (cw, "fg=black")
DrawLine (cw, HOME_X, HOME_Y, x, y)
FillCircle (cw, x, y, SIZE+2)
WAttrib (cw, "fg=yellow")
FillCircle (cw, x, y, SIZE)
# free reference to screen area
Uncouple (cw)
end
# find the average of given two arguments
method avg (a, b)
return (a + b) / 2
end
# this method gets called by the ticker
# it computes the next position of the pendulum and
# requests a redraw
method tick ()
static x, y
static theta := START_ANGLE
static d_theta := 0
# update x,y of pendulum
scaling := 3000.0 / (STRING_LENGTH * STRING_LENGTH)
# -- first estimate
first_dd_theta := -(sin (dtor (theta)) * scaling)
mid_d_theta := d_theta + first_dd_theta
mid_theta := theta + avg (d_theta, mid_d_theta)
# -- second estimate
mid_dd_theta := - (sin (dtor (mid_theta)) * scaling)
mid_d_theta_2 := d_theta + avg (first_dd_theta, mid_dd_theta)
mid_theta_2 := theta + avg (d_theta, mid_d_theta_2)
# -- again first
mid_dd_theta_2 := -(sin (dtor (mid_theta_2)) * scaling)
last_d_theta := mid_d_theta_2 + mid_dd_theta_2
last_theta := mid_theta_2 + avg (mid_d_theta_2, last_d_theta)
# -- again second
last_dd_theta := - (sin (dtor (last_theta)) * scaling)
last_d_theta_2 := mid_d_theta_2 + avg (mid_dd_theta_2, last_dd_theta)
last_theta_2 := mid_theta_2 + avg (mid_d_theta_2, last_d_theta_2)
# -- update stored angles
d_theta := last_d_theta_2
theta := last_theta_2
# -- update x, y
pendulum_angle := dtor (theta)
x := HOME_X + STRING_LENGTH * sin (pendulum_angle)
y := HOME_Y + STRING_LENGTH * cos (pendulum_angle)
# draw pendulum
draw_pendulum (x, y)
end
# set up the window
method component_setup ()
# some cosmetic settings for the window
attrib("size="||WIDTH||","||HEIGHT, "bg=light gray", "label=Pendulum")
# make sure we respond to window close event
connect (self, "dispose", CLOSE_BUTTON_EVENT)
# start the ticker, to update the display periodically
self.set_ticker (20)
end
end
procedure main ()
w := WindowApp ()
w.show_modal ()
end

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require 'gl2 trig'
coinsert 'jgl2'
DT =: %30 NB. seconds
ANGLE=: 0.25p1 NB. radians
L =: 1 NB. metres
G =: 9.80665 NB. ms_2
VEL =: 0 NB. ms_1
PEND=: noun define
pc pend;pn "Pendulum";
xywh 0 0 320 200;cc isi isigraph rightmove bottommove;
pas 0 0;pcenter;
rem form end;
)
pend_run =: verb def ' wd PEND,'';pshow;timer '',":DT * 1000 '
pend_close =: verb def ' wd ''timer 0; pclose'' '
pend_isi_paint=: verb def ' drawPendulum ANGLE '
sys_timer_z_=: verb define
recalcAngle ''
wd 'psel pend; setinvalid isi'
)
recalcAngle=: verb define
accel=. - (G % L) * sin ANGLE
VEL =: VEL + accel * DT
ANGLE=: ANGLE + VEL * DT
)
drawPendulum=: verb define
width=. {. glqwh''
ps=. (-: width) , 40
pe=. ps + 280 <.@* (cos , sin) 0.5p1 + y NB. adjust orientation
glrgb 91 91 91
glbrush''
gllines ps , pe
glellipse (,~ ps - -:) 40 15
glellipse (,~ pe - -:) 20 20
glrect 0 0 ,width, 40
)
pend_run'' NB. run animation

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nomainwin
WindowWidth = 400
WindowHeight = 300
open "Pendulum" for graphics_nsb_nf as #main
#main "down;fill white; flush"
#main "color black"
#main "trapclose [quit.main]"
Angle = asn(1)
DeltaT = 0.1
PendLength = 150
FixX = int(WindowWidth / 2)
FixY = 40
timer 30, [swing]
wait
[swing]
#main "cls"
#main "discard"
PlumbobX = FixX + int(sin(Angle) * PendLength)
PlumbobY = FixY + int(cos(Angle) * PendLength)
AngAccel = -9.81 / PendLength * sin(Angle)
AngVelocity = AngVelocity + AngAccel * DeltaT
Angle = Angle + AngVelocity * DeltaT
#main "backcolor black"
#main "place ";FixX;" ";FixY
#main "circlefilled 3"
#main "line ";FixX;" ";FixY;" ";PlumbobX;" ";PlumbobY
#main "backcolor red"
#main "circlefilled 10"
wait
[quit.main]
close #main
end

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make "angle 45
make "L 1
make "bob 10
to draw.pendulum
clearscreen
seth :angle+180 ; down on screen is 180
forward :L*100-:bob
penup
forward :bob
pendown
arc 360 :bob
end
make "G 9.80665
make "dt 1/30
make "acc 0
make "vel 0
to step.pendulum
make "acc -:G / :L * sin :angle
make "vel :vel + :acc * :dt
make "angle :angle + :vel * :dt
wait :dt*60
draw.pendulum
end
hideturtle
until [key?] [step.pendulum]

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freq = 8; length = freq^(-1/2);
Animate[Graphics[
List[{Line[{{0, 0}, length {Sin[T], -Cos[T]}} /. {T -> (Pi/6) Cos[2 Pi freq t]}], PointSize[Large],
Point[{length {Sin[T], -Cos[T]}} /. {T -> (Pi/6) Cos[2 Pi freq t]}]}],
PlotRange -> {{-0.3, 0.3}, {-0.5, 0}}], {t, 0, 1}, AnimationRate -> 0.07]