Keep It Simple, Stupid PerlMonks

### ztk-roller-coaster-simulation

by zentara (Archbishop)
 on Aug 09, 2005 at 18:03 UTC ( #482340=sourcecode: print w/ replies, xml ) Need Help??
 Category: GUI Programming Author/Contact Info zentara@zentara.net Description: There was an "advanced perl programming" weekly contest awhile back( now defunct I think". One I entered was a roller coaster simulation. The original contest had various *.rc files to make any kind of coaster track design. I just included a nice one in DATA, to make the script self-contained. ```#!/usr/bin/perl use warnings; use strict; use Tk; # by zentara@zentara.net # There was an advanced perl programming contest awhile # back to simulate a roller coaster. This was my entry. # This approach is a very simple method to simulate # the roller-coaster motion. I didn't waste any time # on actually computing the velocities or positions, # rather I relied on the Law of Conservation of Energy, # which says that the sum of the Kinetic and Potential # Energies will remain constant. The initial total energy # is the potential energy at the highest point, and that # is released into kinetic energy( i.e. velocity) as the # coaster drops. So as the coaster drops, # it's KE increases, and as the coaster climbs it's KE # decreases, and stalls if it climbs past it's start height. # # I figured this was the best approach, since we don't have # an actual equation to differentiate to get the instantaneous # values. So this is not mathematically exact, it ignores the # constants in favor of better animation. # After all, it's just a visual simulation, \$|++; my %segs =(); my \$count = 0; # holds how many segments there are my \$action = 0; # action flag my \$cur_loc = 1; # holds current segment in case of stop run my \$cur_ke = 0; # initial kinetic energy my \$g = 10; # gravitational acceleration my \$m = 1; # mass of coaster # (left in for possible future Lorentz transforms + :-)) my \$velocity = 0; # speedometer :-) while(){ \$count++; chomp; next if /^\s*#/ || /^\s*\$/; #skip comments and blank lines my (\$x, \$y) = split(/\s+/, \$_); \$segs{\$count} = [\$x, (400 - \$y) ]; #inverse coords } my \$mw = tkinit; \$mw->geometry("650x450+100+100"); my \$canvas = \$mw->Canvas(-width => 620, -height => 420, -bg => 'black')->pack(); my @s; foreach (1..\$count){ my @str = ( \${\$segs{\$_}}[0], \${\$segs{\$_}}[1] ); push @s, @str; } my \$curve = \$canvas->createLine( @s, -width => 5, -smooth => 1, -fill => 'lightgreen'); my \$coaster = \$canvas->createOval(\${\$segs{1}}[0] - 5,\${\$segs{1}}[1] - +5, \${\$segs{1}}[0] + 5 ,\${\$segs{1}}[1] + + 5, -fill => 'yellow'); my \$group = \$canvas->createGroup([\${\$segs{1}}[0],\${\$segs{1}}[1]], -members => [\$coaster]); my \$subframe = \$mw->Frame(-background =>'gray50')->pack(-fill => 'x'); \$subframe->Button(-text =>'Exit', -background => 'hotpink', -activebackground => 'red', -command => sub{ exit } )->pack(-side=>'left',-padx=>40); \$subframe->Button(-text =>'Slower', -background => 'lightyellow', -activebackground => 'yellow', -command => sub{ if(\$g < 3) { print chr(07);return} else{\$g *= .8; print "\$g\n"; } } #not too slo +w :-) )->pack(-side=>'left',-padx=>40); \$subframe->Label(-text =>'Velocity ', -background => 'black', -foreground => 'green', )->pack(-side=>'left'); \$subframe->Label(-textvariable => \\$velocity, -width => 5, -background => 'black', -foreground => 'green', )->pack(-side=>'left'); \$subframe->Button(-text =>'Faster', -background => 'lightgreen', -activebackground => 'green', -command => sub{ \$g *= 1.25; print "\$g\n"; } )->pack(-side=>'left',-padx=>40); my \$actbut; \$actbut = \$subframe->Button(-text =>'Start', -background =>'lightsteelblue', -activebackground =>'lightskyblue', -command => sub { &action(\$cur_loc,\$cur_ke) }, )->pack(-side=>'right',-padx=>40); MainLoop; ###################################################################### +# sub action { if( \$actbut->cget(-text) eq 'Start'){ \$actbut->configure(-text=>'Stop'); \$action = 1; }else{ \$actbut->configure(-text=>'Start'); \$action = 0; } my (\$cur_seg,\$cur_ke,) = @_; my \$dt; # potential energy at start my \$pe_max = \$m*\$g*(\${\$segs{1}}[1]); #Energy is conserved so at any point # pe_max = pe_current + ke_current # so # ke_current = pe_max - pe_current (both directly proportion to y) while( \$action ){ my \$cur = \$cur_seg; my \$cur_next = \$cur_seg + 1; if(\$cur_next > \$count ){ \$action = 0; \$actbut->configure(-text=>'Start'); \$cur_next = 1; } my \$x1 = \${\$segs{\$cur}}[0]; my \$y1 = \${\$segs{\$cur}}[1]; my \$x2 = \${\$segs{\$cur_next}}[0]; my \$y2 = \${\$segs{\$cur_next}}[1]; my \$dx = \$x2 - \$x1; my \$dy = \$y2 - \$y1; my \$distance = sqrt( \$dx**2 + \$dy**2); # compute average y of segment my \$y_ave = (\$y2 + \$y1)/2; \$cur_ke = \$m*\$g*\$y_ave - \$pe_max; #print "dy->\$dy\tcur_ke->\$cur_ke\n"; \$canvas->move(\$group, \$dx,\$dy); \$canvas->update; if(\$cur_next > \$count ){ \$cur_seg = 1} else {\$cur_seg++} # velocity is proportional to the sqrt of ke # and time is inverse to velocity # \$v = \$distance/\$seconds # \$seconds = \$distance/\$v if(\$cur_ke >= 0){ my \$v = sqrt(2*\$cur_ke/\$m); \$dt = \$distance/\$v; # constant 2 added for visual effect if(\$cur_loc >= \$count){ \$cur_loc = 1; \$cur_ke = 0; \$dt = .001; \$velocity = 0; } \$velocity = sprintf('%.1f',\$v); \$velocity = sprintf('%.1f',\$v); #select(undef,undef,undef,\$dt); \$mw->after(\$dt*1000,\$canvas->update); #it's not the best to use a blocking select in Tk #but it's all in microseconds....so no problem #select takes seconds , after takes microseconds }else{ my \$message = 'Uh oh, Out of KE, Get out and push. Hit Start to get moving.' + ; \$mw->messageBox( -background => 'lightyellow', -icon => 'error', -message => \$message, -type => 'OK' ); &restart; } \$cur_loc = \$cur_seg; } #end of while loop if(\$cur_loc >= \$count){ \$cur_loc = 1; \$cur_ke = 0; \$dt = .001; \$velocity = 0; } } ###################################################### sub restart{ \$actbut->configure(-text=>'Start'); \$action = 0; # action flag \$cur_loc = 1; # holds current segment in case of stop run \$cur_ke = 0; # initial kinetic energy \$g = 10; } #################################################### __DATA__ 0 394 2.3575158001877 384.281866472832 4.71503160037539 374.563732945664 6.06061 369.017 8.64383766277946 359.356413328257 11.2270653255589 349.695826656515 12.1212 346.352 14.9606189063128 336.763585101046 17.8000378126256 327.175170202093 18.1818 325.886 21.3125696733328 316.388722429425 24.2424 307.501 27.7057926640821 298.119906713267 30.303 291.085 34.1461008917288 281.852959297317 36.3636 276.526 40.6402587824946 267.486631125011 42.4242 263.716 47.1938854848266 254.926796374197 48.4848 252.548 53.8116714994823 244.084877643092 54.5455 242.919 60.4934607710689 234.880233759723 60.6061 234.728 66.6667 227.877 72.7273 222.27 78.7879 217.814 84.8485 214.419 90.9091 211.996 96.9697 210.461 103.03 209.73 109.091 209.724 115.152 210.365 121.212 211.578 127.273 213.29 133.333 215.432 139.394 217.937 145.455 220.74 151.515 223.779 157.576 226.994 163.636 230.329 169.697 233.73 175.758 237.145 181.818 240.524 187.879 243.822 193.939 246.994 200 250 206.061 252.8 212.121 255.359 218.182 257.642 224.242 259.62 230.303 261.263 236.364 262.546 242.424 263.445 248.485 263.941 254.545 264.015 260.606 263.652 266.667 262.84 272.727 261.566 278.788 259.826 284.848 257.612 290.909 254.923 296.97 251.759 303.03 248.123 309.091 244.02 315.152 239.458 321.212 234.447 327.273 229.001 333.333 223.136 339.394 216.869 345.455 210.221 352.643002659968 203.268833592304 354.481768427949 201.490397188131 362.484429036145 195.493946305314 364.531592772057 193.959991862849 373.222704590131 189.013824117439 375.445981298941 187.74854301458 384.688480301704 183.930662426619 387.052807581594 182.954008902201 396.700934038571 180.324625729254 399.169025035956 179.652002192781 409.070622229409 178.252583378201 411.603553674894 177.894597504649 421.602467502155 177.747212719114 424.160293553745 177.70951015956 434.098835170697 178.816483749183 436.641217383587 179.099659095513 446.362650051933 181.44353342551 448.84949353988 182.043120833352 458.200504459138 185.586931605377 460.59259021477 186.493475223133 469.425708356719 191.181334424342 471.685311758706 192.380537517617 479.861233573601 198.138514808014 481.952719326472 199.611465227658 489.342505643231 206.348753865726 491.23288976727 208.072222303723 497.719999241234 215.682571222978 499.379469249544 217.62937755251 504.861596289098 225.992767004293 506.26398134833 228.132208926579 510.654669535195 237.116743263189 511.777853195219 239.415080501073 515.007858753819 248.879068248921 515.83412773736 251.300054651201 517.852511550524 261.094243069991 518.368835102122 263.599698234877 519.143766051391 273.56962712248 519.342001440201 276.120038525336 518.738279337106 288.663622276907 516.567189851047 301.032629680655 512.862972360167 313.031994100935 507.684044587088 324.472478392768 501.112081316534 335.173659284657 493.250726335181 344.966772761361 484.223957907231 353.69737557323 474.174133563124 361.227780898512 463.25974503624 367.439229746781 451.652918753587 372.23376385916 439.536701299225 375.53577056858 427.102172660287 377.293175256712 414.545432781436 377.478262601801 402.064508951594 376.088113665848 389.856232795301 373.144651928009 378.113136120411 368.694297538228 367.020414576475 362.807235243744 356.753007008709 355.576307533703 347.472836567911 347.115550457639 339.326257085636 337.558395208851 332.441744986851 327.055563834782 326.927873139962 315.772692260288 322.871598597821 303.88771811016 320.336891233059 291.588074526484 319.363724894979 279.067734236025 319.844467933595 269.079296613913 319.967446998075 266.524150484454 321.696282419674 256.674727755937 322.138536484133 254.155143080706 325.088199521363 244.600066525973 325.842753975014 242.155778660426 329.966726679732 233.045737544671 331.021681748093 230.715294368593 336.254926607204 222.193959482286 337.593645018647 220.014113476704 343.974841901801 212.314741662171 350.356038784956 204.615369847639 351.515 203.217 357.576 195.881 363.636 188.244 369.697 180.335 375.666385374612 172.312130298368 375.758 172.189 381.633028197966 164.096778817092 381.818 163.842 387.61969231521 155.697040437201 387.879 155.333 393.626601717571 147.149780920923 393.939 146.705 399.653041916071 138.498312179607 400 138 404.640414267479 129.141865014227 405.81598125221 126.89781298884 408.107679782248 117.163948502038 408.688241123453 114.698045876763 408.436304962584 102.167254899028 405.076002845147 90.0927957377904 398.818474911509 79.2333510689053 390.056904655316 70.2712597391627 379.341813758568 63.7696429070766 367.346470789654 60.137021069481 354.824587263097 59.6016452162806 342.562959173137 62.1971549813068 331.33202970778 67.7604649404056 321.837479469802 75.9420118684241 314.675885969171 86.2277190822502 310.297238464027 97.971297769454 308.97666348066 110.434855691257 310.429170584783 120.328804504166 310.797137602009 122.835261665674 314.66453653838 132.057150055096 315.644273743794 134.393352579828 321.683561613942 142.363735382522 323.213508515707 144.382891073898 331.045214651804 150.600959825354 333.029239059331 152.176197705349 342.161268561844 156.251248277456 344.474706924877 157.283590356751 354.33326079491 158.959572335074 356.830751272868 159.384152764138 366.796380313541 158.55575803715 369.320996394566 158.345898866128 378.767523482234 155.065178521148 381.160634253068 154.234065973563 389.494499348916 148.707159735512 391.605736858581 147.307015669346 397.858607118376 139.503067084548 404.111477378172 131.69911849975 406.061 129.266 411.770871873657 121.056410291225 412.121 120.553 417.86299660093 112.365846951784 418.182 111.911 423.980344212755 103.763656605346 424.242 103.396 430.125275198168 95.3097726384533 430.303 95.0655 436.30021327201 87.0634107121933 436.364 86.9783 442.424 79.1971 448.485 71.7868 454.545 64.8148 460.606 58.3514 466.667 52.4691 472.727 47.2434 478.788 42.7519 484.848 39.0753 490.909 36.2966 496.97 34.5013 503.03 33.7778 509.091 34.2169 515.152 35.912 521.212 38.9591 527.273 43.4567 533.333 49.5062 539.394 57.2112 544.785915229373 65.6330317579525 545.455 66.6781 550.168858249756 75.497370967671 551.515 78.0159 555.656632956219 87.1179259533778 557.576 91.3361 561.234281192232 100.642924308998 563.636 106.753 566.88712748787 116.20975261692 569.697 124.383 572.602168703062 133.951698699758 575.507337406125 143.520397399516 575.758 144.346 578.367632568624 153.999487341722 580.977265137247 163.652974683443 581.818 166.763 584.174501002549 176.481379650177 586.531002005099 186.199759300355 587.879 191.759 590.015958271494 201.528002474454 592.152916542988 211.297004948909 593.939 219.462 595.885767200493 229.270674602977 597.832534400985 239.079349205954 599.779301601478 248.888023808931 600 250 ```
Comment on ztk-roller-coaster-simulation
Replies are listed 'Best First'.
Re: ztk-roller-coaster-simulation
by chanio (Priest) on Aug 10, 2005 at 04:40 UTC
Nice!

Let me contribute by pollishing up the look of your script (you deserve this):

```use Tk;
before them with this...)

```
use Getopt::Long;
use Pod::Usage;

use Tk;

my \$VERSION='1.00';

=pod

[ TkRollerCoaster.pl ]

There was an "advanced perl programming" weekly contest awhile back(
+now defunct I think".
One I entered was a roller coaster simulation. The original contest h
to make any kind of coaster track design. I just included a nice one
+in DATA, to make the script self-contained.

This approach is a very simple method to simulate
the roller-coaster motion. I didn't waste any time
on actually computing the velocities or positions,
rather I relied on the Law of Conservation of Energy,
which says that the sum of the Kinetic and Potential
Energies will remain constant. The initial total energy
is the potential energy at the highest point, and that
is released into kinetic energy( i.e. velocity) as the
coaster drops.  So as the coaster drops,
it's KE increases, and as the coaster climbs it's KE
decreases, and stalls if it climbs past it's start height.

I figured this was the best approach, since we don't have
an actual equation to differentiate to get the instantaneous
values. So this is not mathematically exact, it ignores the
constants in favor of better animation.
After all, it's just a visual simulation,

(-)-h(elp)       Help: shows these options
(-)-m(an)        man : shows this pod
(-)-v(ersion)    print Modules, Perl, OS, Program info

=item B<--version o -v>

Prints module && script versions

=item B<man>

Man: shows these options

=item B<help>

Help: shows this pod

=back

Roller Coaster

fun

any

zentara #http://perlmonks.org/index.pl?node_id=131741# << zentara@zen
+tara.net >> ~  Aug 09, 2005 at 15:03 ART (#482340)~

=cut

my (\$opt_help, \$opt_man, \$opt_versions);

GetOptions(
## EXPECTED GETOPT: ! JUST MENTION THE WORD

'help!'     => \\$opt_help,
'man!'      => \\$opt_man,
'versions!' => \\$opt_versions,
) or
pod2usage(-verbose => 1 ) && exit;  ## EXIT WITH SOME INFO

pod2usage(-verbose => 1)          && exit if defined \$opt_help;
pod2usage(-verbose => 2)          && exit if defined \$opt_man;

if(defined \$opt_versions)
{
print
"\nModules, Perl, OS, Program info:\n",
"  Pod::Usage            \$Pod::Usage::VERSION\n",
"  Getopt::Long          \$Getopt::Long::VERSION\n",
"  strict                \$strict::VERSION\n",
"  Perl                  \$]\n",
"  OS                    \$^O\n",
"  TkRolerCoaster.pl     \$VERSION\n",
"  \$0\n",
"\n\n";
exit;
}
Then it looks more professional, don't you think so?

Thank you!

 { \ ( ' v ' ) / } ( \ _ / ) _ _ _ _ ` ( ) ' _ _ _ _ ( = ( ^ Y ^ ) = ( _ _ ^ ^ ^ ^ _ _ _ _ \ _ ( m _ _ _ m ) _ _ _ _ _ _ _ _ _ ) c h i a n o , a l b e r t o
Wherever I lay my KNOPPIX disk, a new FREE LINUX nation could be established
Thanks. I'll update it later. Maybe this is the "nudge" I need to get over my "pod-o-phobia". :-)

I'm not really a human, but I play one on earth. flash japh

Create A New User
Node Status?
node history
Node Type: sourcecode [id://482340]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others contemplating the Monastery: (15)
As of 2016-05-27 13:10 GMT
Sections?
Information?
Find Nodes?
Leftovers?
Voting Booth?
What font do you use for programming?

Results (358 votes). Check out past polls.