TheGameCreators - CodeBase - Circle Collision

Category: 2D

Version: 2.0

Information

Uploaded: 26th Mar 2007 16:01

Modified: 25th Sep 2007 22:04

Author: HeavyAmp

Summary

This Function Detects if two circles have collided and will then apply the collision to the circles. This collision doesn't rely on forces to repel each circle making it more accurate if you are using it with lots of objects colliding with each other. However this method is a little slower than if you use your collision using forces. The function Comes with an example.

Full Description

DarkBASIC Professional Source Code

` This code was downloaded from The Game Creators

` It is reproduced here with full permission

` http://www.thegamecreators.com

Sync On : Set display mode 1280,1024,32

Type Unit

x as float

y as float

radius as float

EndType

`Create Units

Dim Unit(2) as Unit

`Initialize Units

Unit(1).Radius=50

Unit(1).x=100

Unit(1).y=100

Unit(2).x=(screen width()/2)

Unit(2).y=(screen height()/2)

Unit(2).Radius=100

Set Cursor 0,0 : Print "Use Arrow keys to move object"

`Move Object

If Upkey()=1 then Unit(1).Y=Unit(1).Y-1

If Downkey()=1 then Unit(1).Y=Unit(1).Y+1

If Leftkey()=1 then Unit(1).X=Unit(1).X-1

If Rightkey()=1 then Unit(1).X=Unit(1).X+1

`Implement Collsion

Collision(Unit(1).x, Unit(1).y, Unit(1).Radius, Unit(2).x,Unit(2).y,Unit(2).Radius)

Unit(1).x = ReturnValueX

Unit(1).y = ReturnValueY

`Draw Objects

Circle Unit(1).x,Unit(1).y,Unit(1).Radius

Circle Unit(2).x,Unit(2).y,Unit(2).Radius

sync : cls

loop

Function Collision(Object1X as Float, Object1Y as Float , Object1Radius as Float, Object2X as Float, Object2Y as Float, Object2Radius as Float)

Local DistX as Float : Local RadCord1X as Float : Local RadCord2X as Float : Local MoveX as Float

Local DistY as Float : Local RadCord1Y as Float : Local RadCord2Y as Float : Local MoveY as Float

Local Distance as Float : ColAngle as Float

`Values that we send Back

Global ReturnValueX as Float

Global ReturnValueY as Float

`Set the return Value to equal the Objects Position

ReturnValueX = Object1X

ReturnValueY = Object1Y

`Calculate the distance between the two units

Distance = sqrt((Object1X - Object2X)^2 + (Object1Y - Object2Y)^2)

`If the distance is less than their radius, ie If they have collided

If Distance < Object1Radius + Object2Radius

`Calculate the X and Y distance between Each Unit

DistX=(Object2X)-(Object1X)

DistY=(Object2Y)-(Object1Y)

`Calculate the Angle between the Two Units

`Note: Use atan2() in c++

ColAngle=ATANFULL(DistY,DistX)

`Get the cords of the First Units radius in the direction of the collsion

DistX=Cos(ColAngle)*(Object1Radius)

DistY=Sin(ColAngle)*(Object1Radius)

`Add the distance to the first units cords

RadCord1X=(Object1X + DistX)

RadCord1Y=(Object1Y + DistY)

`Get the cords of the Second Units radius in the direction of the collsion

DistX=Cos(ColAngle)*(Object2Radius)

DistY=Sin(ColAngle)*(Object2Radius)

`Minus the distance to the second units cords

RadCord2X=(Object2X - DistX)

RadCord2Y=(Object2Y - DistY)

`Get the distance between the two radius cords

DistX=(RadCord1X)-(RadCord2X)

DistY=(RadCord1Y)-(RadCord2Y)

`Get the Distance to move the Unit away From the Other Unit

MoveX=cos(ColAngle)*(DistX)

MoveY=sin(ColAngle)*(DistY)

`Set the return value to equal our new objects position

If DistX<0 then ReturnValueX = Object1X + MoveX

If DistY<0 then ReturnValueY = Object1Y + MoveY

If DistX>0 then ReturnValueX = Object1X - MoveX

If DistY>0 then ReturnValueY = Object1Y - MoveY

EndIf

EndFunction `(ReturnValueX,ReturnValueY)

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Author Name:	HeavyAmp
CodeBase Entries:	3

CodeBase - Circle Collision