diff options
Diffstat (limited to 'library')
| -rw-r--r-- | library/demos/pendulum.tcl | 33 |
1 files changed, 18 insertions, 15 deletions
diff --git a/library/demos/pendulum.tcl b/library/demos/pendulum.tcl index 8512d24..e920c5d 100644 --- a/library/demos/pendulum.tcl +++ b/library/demos/pendulum.tcl @@ -3,7 +3,7 @@ # This demonstration illustrates how Tcl/Tk can be used to construct # simulations of physical systems. # -# RCS: @(#) $Id: pendulum.tcl,v 1.4 2009/04/02 08:27:51 patthoyts Exp $ +# RCS: @(#) $Id: pendulum.tcl,v 1.5 2009/08/08 08:23:40 dkf Exp $ if {![info exists widgetDemo]} { error "This script should be run from the \"widget\" demo." @@ -35,10 +35,10 @@ $w.p add [labelframe $w.p.l2 -text "Phase Space"] canvas $w.c -width 320 -height 200 -background white -bd 2 -relief sunken $w.c create text 5 5 -anchor nw -text "Click to Adjust Bob Start Position" # Coordinates of these items don't matter; they will be set properly below -$w.c create line 0 25 320 25 -width 2 -fill grey50 -tags plate -$w.c create line 1 1 1 1 -tags pendulumRod -width 3 -fill black -$w.c create oval 1 1 2 2 -tags pendulumBob -fill yellow -outline black -$w.c create oval 155 20 165 30 -fill grey50 -outline {} +$w.c create line 0 25 320 25 -tags plate -fill grey50 -width 2 +$w.c create oval 155 20 165 30 -tags pivot -fill grey50 -outline {} +$w.c create line 1 1 1 1 -tags rod -fill black -width 3 +$w.c create oval 1 1 2 2 -tags bob -fill yellow -outline black pack $w.c -in $w.p.l1 -fill both -expand true # Create the canvas containing the phase space graph; this consists of @@ -62,6 +62,7 @@ set Theta 45.0 set dTheta 0.0 set pi 3.1415926535897933 set length 150 +set home 160 # This procedure makes the pendulum appear at the correct place on the # canvas. If the additional arguments "at $x $y" are passed (the 'at' @@ -70,20 +71,20 @@ set length 150 # length and angle are computed in reverse from the given location # (which is taken to be the centre of the pendulum bob.) proc showPendulum {canvas {at {}} {x {}} {y {}}} { - global Theta dTheta pi length - if {$at eq "at" && ($x!=160 || $y!=25)} { + global Theta dTheta pi length home + if {$at eq "at" && ($x!=$home || $y!=25)} { set dTheta 0.0 - set x2 [expr {$x-160}] - set y2 [expr {$y-25}] - set length [expr {hypot($x2,$y2)}] - set Theta [expr {atan2($x2,$y2)*180/$pi}] + set x2 [expr {$x - $home}] + set y2 [expr {$y - 25}] + set length [expr {hypot($x2, $y2)}] + set Theta [expr {atan2($x2, $y2) * 180/$pi}] } else { set angle [expr {$Theta * $pi/180}] - set x [expr {160+$length*sin($angle)}] - set y [expr {25+$length*cos($angle)}] + set x [expr {$home + $length*sin($angle)}] + set y [expr {25 + $length*cos($angle)}] } - $canvas coords pendulumRod 160 25 $x $y - $canvas coords pendulumBob \ + $canvas coords rod $home 25 $x $y + $canvas coords bob \ [expr {$x-15}] [expr {$y-15}] [expr {$x+15}] [expr {$y+15}] } showPendulum $w.c @@ -127,6 +128,8 @@ bind $w.c <ButtonRelease-1> { } bind $w.c <Configure> { %W coords plate 0 25 %w 25 + set home [expr %w/2] + %W coords pivot [expr $home-5] 20 [expr $home+5] 30 } bind $w.k <Configure> { set psh [expr %h/2] |