TheGameCreators - CodeBase - Elastic Simulation

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Category: Math / Physics

Version: 2.0

Information

Uploaded: 26th Sep 2003 16:02

Modified: 26th Sep 2003 20:24

Author: Hamish McHaggis

Summary

A simulation of beads on a piece of elastic...

Full Description

Move the mouse around while holding a bead to make the elastic bounce around the screen, and off walls. This is the second version of my code. In this version you can hold any bead and fix/release the beads in the air by pressing 'f'. You can do some fun stuff with this extra option. Feel free to change the default settings (the constant commands) as see what happens, I'd recommend you change them in small steps ;). .EXE BELOW...

DarkBASIC Professional Source Code

` This code was downloaded from The Game Creators

` It is reproduced here with full permission

` http://www.thegamecreators.com

`Elastic Physics Demo

`By Hamish McHaggis

`26/9/03

`This code demonstrates how to simulate the properties of elastic.  I saw it first on a javascript mouse

`trail, I have recreated it without looking at any of the javascript code.

`The amount of gravity acting on the beads

#CONSTANT GRAVITY 0.04

`The decay of the X movement of the beads, 1=no decay, 0=complete decay

#CONSTANT XDECAY 0.97

`The decay of the Y movement of the beads, 1=no decay, 0=complete decay

#CONSTANT YDECAY 0.97

`The number of beads on the string take into account that each bead weighs the beads above it down

#CONSTANT NUMBEADS 10

`The elasticity of the X movement of the beads

#CONSTANT XELASTICITY 0.02

`The elasticity of the Y movement of the beads

#CONSTANT YELASTICITY 0.02

`The amount the bead movement decays when it hits a wall, 1=no decay, 0=complete decay

#CONSTANT WALLDECAY 0.9

`The between beads, before the string tenses and elasticity acts

#CONSTANT SLACKNESS 1

`The diameter of the beads

#CONSTANT BEADSIZE 6

`Screen mode

screenWidth as word = 800

screenHeight as word = 600

set display mode screenWidth,screenHeight,16

beadDist as float

beadDistX as float

beadDistY as float

distRatioX as float

distRatioY as float

sync on

sync rate 60

type beadType

X as float

Y as float

xMove as float

yMove as float

endtype

dim bead(NUMBEADS) as beadType

position mouse 0,0

`Draw background

ink rgb(255,255,255),0

box 0,0,screenWidth,screenHeight

`Position parent bead

bead(1).X=mousex()

bead(1).Y=mousey()

if bead(1).X-(BEADSIZE+10)/2<0 then bead(1).X=(BEADSIZE+10)/2

if bead(1).X+(BEADSIZE+10)/2>screenWidth then bead(1).X=screenWidth-(BEADSIZE+10)/2

if bead(1).Y-(BEADSIZE+10)/2<0 then bead(1).Y=(BEADSIZE+10)/2

if bead(1).Y+(BEADSIZE+10)/2>screenHeight then bead(1).Y=screenHeight-(BEADSIZE+10)/2

`Draw parent bead

ink rgb(0,0,0),0

circle bead(1).X,bead(1).Y,BEADSIZE

`Loop though other beads

for x=2 to NUMBEADS

`Work out X and Y distance between the bead and the one before it

beadDistX=bead(x).X-bead(x-1).X

beadDistY=bead(x).Y-bead(x-1).Y

`Work out total distance

beadDist=sqrt(beadDistX^2+beadDistY^2)

`If the beads are far enough apart, decrease the movement to create elasticity

if beadDist>SLACKNESS

dec bead(x).xMove,XELASTICITY*beadDistX

dec bead(x).yMove,YELASTICITY*beadDistY

endif

`If bead is not last bead

if x<>NUMBEADS

`Work out distances between the bead and the one after it

beadDistX=bead(x).X-bead(x+1).X

beadDistY=bead(x).Y-bead(x+1).Y

beadDist=sqrt(beadDistX^2+beadDistY^2)

`If the beads are far enough apart, decrease the movement to create elasticity

if beadDist>1

dec bead(x).xMove,XELASTICITY*beadDistX

dec bead(x).yMove,YELASTICITY*beadDistY

endif

`Decay the movement of the beads to simulate loss of energy

bead(x).xMove=bead(x).xMove*XDECAY

bead(x).yMove=bead(x).yMove*YDECAY

`Apply gravity to bead movement

inc bead(x).yMove,GRAVITY

`Move beads

inc bead(x).X,bead(x).xMove

inc bead(x).Y,bead(x).yMove

`If the beads hit a wall, make them bounce off of it

if bead(x).X-(BEADSIZE+10)/2<0

bead(x).X=+(BEADSIZE+10)/2

bead(x).xMove=-bead(x).xMove*WALLDECAY

endif

if bead(x).X+(BEADSIZE+10)/2>screenWidth

bead(x).X=screenWidth-(BEADSIZE+10)/2

bead(x).xMove=-bead(x).xMove*WALLDECAY

endif

if bead(x).Y-(BEADSIZE+10)/2<0

bead(x).yMove=-bead(x).yMove*WALLDECAY

bead(x).Y=(BEADSIZE+10)/2

endif

if bead(x).Y+(BEADSIZE+10)/2>screenHeight

bead(x).yMove=-bead(x).yMove*WALLDECAY

bead(x).Y=screenHeight-(BEADSIZE+10)/2

endif

`Draw bead and string from it to the one before it

ink rgb(0,0,0),0

circle bead(x).X,bead(x).Y,BEADSIZE

ink rgb(200,100,0),0

line bead(x).X,bead(x).Y,bead(x-1).X,bead(x-1).Y

next x

sync

cls

loop

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Author Name:	Hamish McHaggis
CodeBase Entries:	14

CodeBase - Elastic Simulation

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