# Rubble Trouble!

Model was written in NetLogo 6.3.0
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; extensions [ sound ] globals [ pixel keypress the-ship the-reticule click num-rocks active-reticule score credits reset-pressed rock-color setup-finished rock-info ] patches-own [ rr gg bb ] breed [ rocks rock ] breed [ ships ship ] breed [ bullets bullet ] breed [ fragments fragment ] breed [ messengers messenger ] breed [ reticules reticule ] breed [ letters letter ] breed [ clocks clock ] breed [ HS-effects hs-effect ] clocks-own [ current-time elapsed-time start-time cumulative-time pause-until clock-on ] letters-own [ base-size base-color base-xcor base-heading ] reticules-own [ timeout ] hs-effects-own [ effect-direction ] ships-own [ vx vy vv ax ay av gun-temp gun-limit gun-cooldown max-temp bullet-speed; bullet-burnout max-burnout ] rocks-own [ rock-type vx vy vv av exploding ] bullets-own [ vx vy vv bullet-burnout bullet-speed max-burnout seeker? target-rock ] fragments-own [ vv vx vy av burnout max-burnout kind ] messengers-own [ text ;; the message to ;display caret ;; position within the text cursor ;; patch offset of the caret window ;; the set of patches under the message window# ;; the line on which to ;display the message show-cursor? ;; show the simulated blinking curtor ] to ? [ thing ] ( ifelse ( is-list? thing ) [ output-print " [ " foreach thing [ ?? -> ? ?? ] output-print " ] " ] [ output-print thing ] ) end to-report plus-or-minus [ value ] report value * ( random 2 * 2 - 1 ) end to x_set-line-thickness [ width ] ;; __set-line-thickness width end to setup-rock let rock-start-size 1.5 ^ 5 let rock-start-av .1 + random-float 0.75 let rock-start-v .1 + random-float .1 set rock-info [ [ "rock-1" 0 1 22 ] [ "rock-2" 0 1 22 ] [ "rock-3" 0 1 22 ] [ "rock-4" 0 1 22 ] [ "rock-5" 1 2 12 ] ] create-rocks 1 [ home x_set-line-thickness pixel * 2 let side plus-or-minus 1 let startx side * ( max-pxcor - random ( world-width / 4 ) ) let starty random-ycor setxy startx starty let endx side * ( max-pxcor - random ( world-width / 4 ) ) set heading towardsxy endx plus-or-minus max-pycor set vx dx * rock-start-v set vy dy * rock-start-v set av rock-start-av set color white set rock-type item ( roulette rock-info 3 ) rock-info set shape item 0 rock-type set size rock-start-size / item 2 rock-type ] end to-report roulette [ $layout $bias-index ] ;; the layout are the values being selected from ;; the canoes are widths of each pocket the tendency of each value to be selected let canoes map [ $bias -> item $bias-index $bias ] $layout let total sum canoes let fall random-float total let pocket 0 ;; intial value of canoe = inside the first pocket let canoe item pocket canoes while [ fall > canoe ] [ set pocket pocket + 1 set canoe canoe + item pocket canoes ] report pocket end to rock-explode ;; sound:play-note-later delay instrument keynumber velocity duration sfx "explode-rock" size set heading atan vx vy set vv sqrt ( vx * vx + vy * vy ) if ( size > 4 ) [ set size size * 2 / 3 if vv < .9 [ set vv vv * 1.1 ] let a -1 repeat (1 + random 2) [ hatch 1 [ rt 90 * a set a a + 2 set vx dx * vv set vy dy * vv jump size / 2 set shape one-of [ "rock-1" "rock-2" "rock-2" ] x_set-line-thickness pixel * 2 ] ] ] fragment-setup white 0 size die end to fragment-setup [ hue direction radius ] let xx xcor let yy ycor let $extra max list 0 (count fragments - 100) ask n-of $extra fragments [ die ] hatch-fragments ifelse-value ( direction = 0 ) [ 5 ] [ 1 ] [ set color hue set heading random 360 x_set-line-thickness pixel * 2 set vv .1 + random-float .2 set vx dx * vv set vy dy * vv set max-burnout 40 ifelse direction != 0 [ jump 2 rt 180 set size 2 set av 0 ] [ jump ( .5 * random-float radius ) rt 90 set size ( size + random-float 2 ) set av 20 * ( random 2 * 2 - 1 ) ] ] end to game-clear ;; setup a game clear-drawing clear-patches clear-turtles clear-links set num-rocks 0 end to ship-setup create-ships 1 [ set color magenta + 2 set heading 0 set shape "_ship-000" x_set-line-thickness pixel * 2 set size 2 set bullet-speed 1 set bullet-burnout max-pxcor / bullet-speed set max-burnout bullet-burnout set gun-limit 5 set gun-temp 0 set max-temp 4 / bullet-speed ;; floor ( 30 / 2 / pixel ) set the-ship self ] inspect the-ship end to reticule-setup ask patch min-pxcor min-pycor [ sprout-reticules 1 [ hide-turtle setxy max-pxcor max-pycor set heading 0 set shape "reticule" set color red x_set-line-thickness pixel * 3 set size 2 set active-reticule self set timeout 0 ] ] end to reticules-go if self != active-reticule [ if timeout = 0 [ set timeout timer + 2 ] ifelse timer < timeout [ set color scale-color red ( timeout - timer ) -3 8 ] [ die ] ] end to ship-explode sfx "ship-explode" 0 die end to-report ship-fire ;; SETUP-bullet let fire! false ask the-ship [ if gun-temp <= 0 and count bullets < gun-limit [ sfx "pew" 0 hatch-bullets 1 [ x_set-line-thickness pixel * 4 set size max list .5 ( pixel * 3 ) set color white set vx dx * ( bullet-speed ) set vy dy * ( bullet-speed ) jump .5 set fire! true set seeker? false let vary random 100 ( ifelse ( vary > 90 ) ;; hunter missle [ set seeker? true set size .5 set shape "missle" set target-rock one-of rocks set color yellow set bullet-burnout 200 ] ( vary > 80 ) ;; triple shot [ hatch 1 [ rt 90 jump .5 lt 90 ] hatch 1 [ lt 90 jump .5 rt 90 ] ] ( vary > 70 ) ;; to left, right, and center [ hatch 1 [ rt 90 ] hatch 1 [ lt 90 ] ] ( vary > 60 ) ;; four-way shot [ hatch 1 [ rt 90 ] hatch 1 [ lt 90 ] hatch 1 [ rt 180 jump 1 ] ] ( vary > 55 ) ;; circle of pebbles [ let a heading setxy [ xcor ] of myself [ ycor ] of myself repeat ( 360 / 5 ) [ hatch 1 [ rt a jump .5 ] set a a + 5 ] jump .5 ] ;; no specialization [ ] ) ] set gun-temp max-temp ] ] report fire! end to rock-go ; if count rocks < 5 and any? ships ; [ ; let hh towards one-of ships ; set vx .5 * sin hh ; set vy .5 * cos hh ; ] set vv ( vx * vx + vy * vy ) ifelse ( vv > 1 ) [ rock-explode ] [ let trail-color red + 10 * int min list 120 ( 10 * size ) setxy ( xcor + vx ) ( ycor + vy ) rt av ask patches in-radius (round (.3 * size)) [set pcolor trail-color ] set color rock-color if ( any? ships in-radius ( size / 2 + .5 ) ) [ ask ships [ ship-explode ] ] if ( true ) [ let close min-one-of ( other rocks ) [ distance myself ] let overlap -1 * boundary-distance close if ( overlap > 2 * pixel ) [ if ( overlap > 4 * pixel ) [ ;; too close! force them away face close rt 180 jump overlap / 2 ask close [ face myself rt 180 jump overlap / 2 ] ] collide-with close ] ] ] end to collide-with [ other-particle ] ;; particle procedure let recovery .99 ;;; PHASE 1: initial setup ;; for convenience, grab some quantities from other-particle let h ifelse-value ( vx != 0 or vy != 0 ) [ atan vx vy ] [ 0 ] let mass size ^ 3 let speed sqrt ( vx * vx + vy * vy ) let mass2 [ size ^ 3 ] of other-particle let speed2 [ sqrt ( vx * vx + vy * vy ) ] of other-particle let h2 [ ifelse-value ( vx != 0 or vy != 0 ) [ atan vx vy ] [ 0 ] ] of other-particle ;;modified so that theta is heading toward other particle let theta towards other-particle ;;; PHASE 2: convert velocities to theta-based vector representation ;; now convert my velocity from speed/heading representation to components ;; along theta and perpendicular to theta let v1t ( speed * cos ( theta - h ) ) let v1l ( speed * sin ( theta - h ) ) ;; do the same for other-particle let v2t ( speed2 * cos ( theta - h2 ) ) let v2l ( speed2 * sin ( theta - h2 ) ) ;;; PHASE 3: manipulate vectors to implement collision ;; compute the velocity of the system's center of mass along theta let vcm ( ( ( mass * v1t ) + ( mass2 * v2t ) ) / ( mass + mass2 ) ) ;; now compute the new velocity for each particle along direction theta. ;; velocity perpendicular to theta is unaffected by a collision along theta, ;; so the next two lines actually implement the collision itself, in the ;; sense that the effects of the collision are exactly the following changes ;; in particle velocity. set v1t ( 2 * vcm - v1t ) set v2t ( 2 * vcm - v2t ) let d distance other-particle - ( size + [ size ] of other-particle ) / 2 ;;; PHASE 4: convert back to normal speed/heading ;; now convert my velocity vector into my new speed and heading set speed recovery * sqrt ( ( v1t * v1t ) + ( v1l * v1l ) ) ;; if the magnitude of the velocity vector is 0, atan is undefined. but ;; speed will be 0, so heading is irrelevant anyway. therefore, in that ;; case we'll just leave it unmodified. if v1l != 0 or v1t != 0 [ let new-h ( theta - ( atan v1l v1t ) ) set vx sin new-h * speed set vy cos new-h * speed setxy xcor + vx ycor + vy ] ;; and do the same for other-particle set speed2 recovery * sqrt ( ( v2t ^ 2 ) + ( v2l ^ 2 ) ) if v2l != 0 or v2t != 0 [ let new-h ( theta - ( atan v2l v2t ) ) ask other-particle [ set vx sin new-h * speed2 set vy cos new-h * speed2 setxy xcor + vx ycor + vy ] ] end to fragment-go setxy xcor + vx ycor + vy rt av if random 10 = 1 [ set av av * 2 set size size / 2 set burnout burnout * 1.5 rt 90 hatch 1 [ rt 180 ] ] set max-burnout max-burnout - 1 ifelse max-burnout > 0 [ if max-burnout < 10 [ set color max-burnout ] ] [ die ] end to-report boundary-distance [ obj ] if not is-turtle? obj [ report world-width ] report ( distance obj - ( size / 2 ) - [ size / 2 ] of obj ) end to ship-go set xcor xcor + vx set ycor ycor + vy ;; ask patches in-radius size [ set pcolor 9.9 ] if gun-temp > 0 [ set gun-temp gun-temp - 1 ] let crowd rocks in-radius 20 if any? crowd [ let close min-one-of crowd [ boundary-distance myself ] let dc abs boundary-distance close if dc <= 2 and dc >= 1 [ fragment-setup turquoise 1 1 ] if ( dc < .5 ) [ ship-teleport ] ] end to bullet-go if seeker? and is-rock? target-rock [ lt .05 * subtract-headings heading towards target-rock ] jump bullet-speed let hits rocks with [ distance myself < size / 2 ] if any? hits [ ask hits [ rock-explode ] set bullet-burnout -1 ] set bullet-burnout bullet-burnout - 1 if bullet-burnout <= 0 [ die ] end to ship-spin-ws ask the-ship [ set shape "_ship-001" lt 15 ] end to ship-spin-cw ask the-ship [ set shape "_ship-100" rt 15 ] end to ship-thrust ask the-ship [ ;; get components of thrust vector let am pixel / 2 set ax am * sin heading set ay am * cos heading ;; add to current velocity vector components let nvx vx + ax let nvy vy + ay ;; calculate new velocity magnitude let maxvm 1.00 let nvm sqrt ( nvx * nvx + nvy * nvy ) let svm ifelse-value ( nvm <= maxvm ) [ 1 ] [ nvm / maxvm ] set vx nvx / svm set vy nvy / svm ;; output-print " xcor ycor heading ax ay am vx vy vm" ;; foreach ( list xcor ycor heading ax ay am vx vy vm ) [ n -> output-type fixed n output-type " " ] output-print "" set shape "_ship-010" ] end to-report fixed [ n ] let m ifelse-value n < 0 [ "-" ] [ " " ] let ns ( word " " ( int n ) "." int ( 100 * ( ( abs n ) - ( abs int n ) ) ) "0" ) set ns reverse substring reverse ns 0 7 report ns end to ship-nothing ask the-ship [ set shape "_ship-000" ] end to message-go ;; draw character, if appropriate ;; at end of message, die let font-size 36 let pix 1 / patch-size let char-width ceiling (font-size / patch-size / 1.5) let char-height font-size / patch-size * 2 ifelse ( caret >= length text ) [ die ] [ let new-x pxcor if ( pxcor >= cursor ) [ let c item caret text if c = "W" or c = "m" or c = "M" [ set new-x new-x + 1 if new-x > max-pxcor - 1 [ set new-x min-pxcor ] set xcor new-x set cursor new-x ] if c = "i" or c = "l" [ set new-x new-x - 1 set xcor new-x set cursor new-x ] set plabel c set caret caret + 1 set cursor cursor + char-width ] ;; advance cursor set new-x new-x + 1 if new-x > max-pxcor - 1 [ set new-x min-pxcor ] set xcor new-x ] end to message-setup [ $window# $text ] let this nobody let font-size 36 let pix 1 / patch-size let char-width ceiling (font-size / patch-size / 1.5) let line-height ceiling(font-size / patch-size * 1.4) ;; get or create the indicated message line ifelse ( any? messengers with [ window# = $window# ] ) [ ;; use existing messenger set this one-of messengers with [ window# = $window# ] ] [ ;; make a new messenger ;; since we can't be sure what is making the message, ;; ask a patch to do it, so we can use SPROUT with certainty. ask patch min-pxcor min-pycor [ sprout-messengers 1 [ set this self ] ] ] ;; now work with the messenger ask this [ set shape "cursor" set size 8 set color black set text $text set window# $window# set show-cursor? false setxy ( min-pxcor + ceiling (char-width / 2) ) ( max-pycor - line-height * window# ) let min-py pycor - ( line-height / 2 ) + 1 let max-py pycor + ( line-height / 2 ) - 1 set window patches with [ pycor >= min-py and pycor <= max-py ] ask window [ set plabel "" set pcolor white set plabel-color black ] set caret 0 set cursor pxcor set hidden? true ;; not show-cursor? ] end to write-message let expiration timer + 10 while [ any? messengers and timer < expiration ] [ repeat 5 [ ask messengers [ message-go ]] tick ] ask messengers [ die ] end to mouse-mode if ( mouse-inside? ) [ let diff [ -1 * subtract-headings towardsxy mouse-xcor mouse-ycor heading ] of the-ship let turn 0 ( ifelse ( diff > 0 ) [ set turn 1 ] ( diff < 0 ) [ set turn -1 ] ;; otherwise [ set turn 0 ] ) ask the-ship [ lt diff / 2 ] ] ifelse ( mouse-down? ) [ ifelse click = 0 [ let void ship-fire set click 1 ] [ ship-thrust ] ] [ set click 0 ] end to auto-pilot ask the-ship [ let diff 0 let close rocks in-radius 20 ifelse ( any? close ) [ set close min-one-of close [ distance myself ] ;if ( not member? close link-neighbors ) ; [ ask my-links [ die ] ; create-link-with close ; ] let dd [ distance myself ] of close let rockspeed [ sqrt ( vx * vx + vy * vy ) ] of close let bullspeed bullet-speed let bx dx * bullspeed let by dy * bullspeed let frx [ xcor + vx * dd / bullspeed ] of close let fry [ ycor + vy * dd / bullspeed ] of close let frh towardsxy frx fry let fdist distancexy frx fry let fhdiff subtract-headings frh heading ;; let dist boundary-distance close ifelse ( abs fhdiff > 2 ) [ ifelse ( fhdiff < 0 ) [ lt 5 ] [ rt 5 ] ] [ ifelse ( fdist > 2 * ( bullet-speed * bullet-burnout ) ) [ ship-thrust ] [ if ship-fire [ if not any? reticules [ reticule-setup ] ask active-reticule [ set timeout timer + 2 setxy frx fry show-turtle ; create-link-with close ; [ set thickness 2 * pixel ; set color violet ; ] hatch 1 [ hide-turtle set active-reticule self set timeout 0 ] ] ] ] ] ] [ let rnd random 100 ( ifelse ( rnd < 5 ) [ ship-spin-ws ] ( rnd >= 40 and rnd < 55 ) [ ship-thrust ] ( rnd >= 90 and rnd < 95 ) [ ship-spin-cw ] [ let void ship-fire ] ) ] ] end to GET-input if ( any? ships ) [ ship-nothing ifelse ( full-auto? ) [ auto-pilot ] [ if ( mouse-mode? ) [ mouse-mode ] ( ifelse ( keypress = "fire" ) [ let void ship-fire ] ( keypress = "ws" ) [ ship-spin-ws ] ( keypress = "cw" ) [ ship-spin-cw ] ( keypress = "t" ) [ ship-thrust ] [ ship-nothing ] ) set keypress "" ] ] end to shapes-setup set-default-shape ships "_ship-000" set-default-shape rocks "rock-1" set-default-shape bullets "bullet" set-default-shape fragments "fragment" set-default-shape messengers "cursor" end to startup clear-all reset-ticks message-setup 1 "Please press RUN" write-message tick end to globals-setup set pixel 1 / patch-size set active-reticule nobody end to rocks-setup if num-rocks = false or num-rocks < 5 [ set num-rocks 5 ] repeat num-rocks [ setup-rock ] let retry-limit 50 let too-many-rocks true while [ too-many-rocks and retry-limit > 0 ] [ set too-many-rocks false ASK ROCKS [ LET too-close OTHER ROCKS IN-RADIUS (SIZE * 2) LET is-too-close? ANY? too-close SET too-many-rocks too-many-rocks OR is-too-close? IF is-too-close? [ RT RANDOM 360 JUMP 1 ] SET retry-limit retry-limit - 1 ] ] end to ship-teleport let max-jumps 100 let crowd rocks in-radius 20 hatch-HS-effects 1 [ set size 3 set color violet set effect-direction 1 set shape "circle" ] while [ max-jumps > 0 and any? crowd with [ boundary-distance myself < 2 ] ] [ fragment-setup green 0 1 setxy random-xcor random-ycor set vx 0 set vy 0 set crowd rocks in-radius 10 set max-jumps max-jumps - 1 ;display ] hatch-HS-effects 1 [ set color red set size 20 set effect-direction -1 set shape "circle" ] fragment-setup lime 1 2 end to clock-setup create-clocks 1 [ set shape "clock" set start-time 0 set current-time 0 set elapsed-time 0 set cumulative-time 0 set pause-until 0 set clock-on false set size 3 setxy 0 max-pycor - size / 2 - pixel ] end to game-setup set score 0 globals-setup shapes-setup game-clear rocks-setup logo-display directions-display write-message clock-setup stop-inspecting-dead-agents set setup-finished true reset-ticks end to new-game set score 0 game-clear rocks-setup ship-setup set setup-finished true end to directions-display message-setup 5 "THE MISSION:" write-message message-setup 6 "DESTROY RUBBLE." write-message message-setup 7 "-PRESS START-" end to game-go ifelse ( setup-finished = 0 ) [ game-setup ] [ get-input ask ships [ ship-go ] ask bullets [ bullet-go ] set rock-color white ;; ifelse-value ( random 100 < 10 ) [ 1 + random-float 1 + 2.9 * random 2 ] [ white ] ask rocks [ rock-go ] ask fragments [ fragment-go ] ask messengers [ message-go ] ask reticules [ reticules-go ] ask HS-effects [ ifelse ( size < 3 or size > 20 ) [ die ] [ set size size + effect-direction ] ] ;; ask aliens [ GO-alien ] ;; if ( not ( any? ships or any? messengers ) ) [ messenger-setup 1 "PRESS PLAY" ] if ( not ( any? rocks ) ) [ set num-rocks num-rocks * 1.25 rocks-setup ask ships [ home set vx 0 set vy 0 ] ] ask patches [ let hue ifelse-value (is-list? pcolor) [pcolor ][ extract-rgb pcolor ] set rr item 0 hue ^ 2 * .95 set gg item 1 hue ^ 2 * .95 set bb item 2 hue ^ 2 * .95 ] diffuse rr .2 diffuse gg .2 diffuse bb .2 ask patches [ set pcolor rgb sqrt rr sqrt gg sqrt bb ] ] tick end to logo-display clear-patches ask letters [ die ] tick ;; ask patches with [ ( pxcor + pycor ) mod 2 = 0 ] [ set pcolor ( 2.5 + black ) ] let logo0 "RUBBLE" let logo1 "TROUBLE" logo-animate logo0 0 logo-animate logo1 1 ;display end to logo-animate [ logo line ] let len length logo let letter-size ( world-width ) / ( len ) let start-x min-pxcor + ( world-width - 1 ) / 2 - ( ( len * letter-size ) / 2 ) + .5 * letter-size let line-height 1.5 let these-letters no-turtles foreach range len [ [ t ] -> create-letters 1 [ let c item t logo let pos-x letter-size * t setxy ( start-x + pos-x ) max-pxcor - letter-size * line * line-height if ( c = " " ) [ set c "space" ] set shape word "logo-" c set size letter-size set color base-color set heading 0 set base-xcor xcor set base-size size set base-color white set color base-color set base-heading heading setxy 0 min-pycor set size 0 set these-letters ( turtle-set these-letters self ) ] ] let top-y ( world-height - 1 ) - ( .5 * letter-size ) - line * letter-size * line-height ( foreach ( range 0 1.0 ( 2 / 30 ) ) [ [ ratio ] -> let y min-pycor + top-y * ratio let m2 ratio * letter-size ask these-letters [ set size m2 set ycor y set xcor base-xcor * ratio ] tick wait 1 / 30 ] ) set pixel 1 / patch-size let thick PIXEL * 16 let lcolor lime - 3.5 ask letters [ let mythick thick LET MYCOLOR LCOLOR repeat 4 [ hatch 1 [ set color MYCOLOR x_set-line-thickness mythick set mythick mythick / 2 SET MYCOLOR MYCOLOR + 2 ] ] DIE ] ; end to play-note [ $inst $key $vel $dur ] ;; sound:play-note $inst $key $vel $dur end to play-note-later [ $delay $inst $key $vel $dur ] ;; sound:play-note-later $delay $inst $key $vel $dur end to play-drum [ $inst $vel ] ;; sound:play-drum $inst $vel end to stop-music ;; sound:stop-music end to sfx [ fx option ] ( ifelse ( fx = "explode-rock" ) [ play-drum "CRASH CYMBAL 2" 12 play-note-later .10 "timpani" ( 45 - option * 4 ) 64 + option .3 play-note "timpani" ( 42 - option * 2 ) 64 + option .1 ] ( fx = "ship-explode" ) [ play-drum "CRASH CYMBAL 2" 127 play-note-later .20 "timpani" 42 100 .1 play-note-later .10 "timpani" 42 100 .1 play-note "timpani" 40 64 .1 ] ( fx = "pew" ) [ let fxarppegio-steps 5 let fxkeys map [ r -> 42 - r * 3 ] ( range fxarppegio-steps ) let fxvelocity 48 let fxduration .02 * fxarppegio-steps let fxdelay-step fxduration / fxarppegio-steps foreach ( range fxarppegio-steps ) [ [ i ] -> play-note-later ( i * fxdelay-step ) "SYNTH BRASS 1" ( item i fxkeys ) fxvelocity fxdelay-step ] ] [ stop-music ] ) end ;; The following code was publsihed by and released to the Public Domain by Uri Wilensky, ;; and was obtained from the NetLogo v 6.3 Model Library. ;; note that the 6.2.2 version used TAN 90, which is mathematically undefined, but ;; netlogo used to incorrectly report as a value ;; reports a two-item list of x and y coordinates, or an empty ;; list if no intersection is found to-report intersection [ t1 t2 ] let is-t1-vertical? ( [ heading ] of t1 = 0 or [ heading ] of t1 = 180 ) let is-t2-vertical? ( [ heading ] of t2 = 0 or [ heading ] of t2 = 180 ) ;; is t1 vertical? if so, swap the two turtles, and run again. ;; ( unless both are vertical, i.e. they are parallel--report an empty list ) ifelse ( is-t1-vertical? ) [ ifelse ( is-t2-vertical? ) [ report [ ] ] [ report intersection t2 t1 ] ;; report ends the procedure immediately ] [ let m1 [ tan ( 90 - heading ) ] of t1 ;; is t2 vertical? if so, handle specially ifelse ( is-t2-vertical? ) [ ;; represent t1 line in slope-intercept form ( y=mx+c ) let c1 [ ycor - xcor * m1 ] of t1 ;; t2 is vertical so we know x already let x [ xcor ] of t2 ;; solve for y let y m1 * x + c1 ;; check if intersection point lies on both segments ifelse [ not x-within? x ] of t1 or [ not y-within? y ] of t2 [ report [ ] ] [ report list x y ] ] [ let m2 [ tan ( 90 - heading ) ] of t2 ;; treat parallel/collinear lines as non-intersecting ifelse m1 = m2 [ report [ ] ] [ ;; now handle the normal case where neither turtle is vertical; ;; start by representing lines in slope-intercept form ( y=mx+c ) let c1 [ ycor - xcor * m1 ] of t1 let c2 [ ycor - xcor * m2 ] of t2 ;; now solve for x let x ( c2 - c1 ) / ( m1 - m2 ) ;; check if intersection point lies on both segments ifelse [ not x-within? x ] of t1 or [ not x-within? x ] of t2 [ report [ ] ] [ report list x ( m1 * x + c1 ) ] ] ] ] end to-report x-within? [ x ] ;; turtle procedure report abs ( xcor - x ) <= abs ( size / 2 * dx ) end to-report y-within? [ y ] ;; turtle procedure report abs ( ycor - y ) <= abs ( size / 2 * dy ) end ;; below only for when generating a new thumbnail image for the commons ;to setup ; clear-all ; startup ; new-game ; set num-rocks 15 ; rocks-setup ;end ;to go ; repeat 15 [ game-go wait 1 / 30 ] ;end

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## Attached files

File | Type | Description | Last updated | |
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Rubble Trouble!.png | preview | Preview for 'Rubble Trouble!' | 5 months ago, by James Steiner | Download |

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