Circular Collision

Can anyone direct me to a tutorial, or perhaps post some code on how to do 2d circular collision?

Thanks.

Not quite sure what you mean by that...

... but you might be looking for an 'EntityDistance()' equivalent. In other words, anything that enters a specific radius around the centre of an 'object' can be considered to have collided with the object.

You can do this using basic pythagoras...

  dist = sqrt( (Xobject - Xtarget)^2 + (Yobject - Ytarget)^2 )
  if dist < CollisionRadius then ....

It may even be more efficient to ignore the square root part and compare to CollisionRadius squared...

  distSquared =  (Xobject - Xtarget)^2 + (Yobject - Ytarget)^2 
  if distSquared < CollisionRadius^2 then ....

Obviously you could wrap this up in a For Each loop around a target type and examine (Xobject - target\Xtarget)^2 + (Yobject - target\Ytarget)^2


I don't have Blitz installed on this laptop or I would have knocked you up a quick demo... I am sure someone with a feuding Xmas family to avoid will be along shortly to rectify this ;-)

I need to see a demo. Any help would be greatly appreciated.

Valorden, how lazy are you?

Function CirclesOverlap(x1#,y1#,r1#,x2#,y2#,r2#)
	x=(x1-x2)
	y=(y1-y2)
	d1 = Sqr((x*x)+(y*y))
	d2 = r1+r2
	If d1<=d2 Then Return True Else Return False
End Function

What I meant is circle to square collisions. It has been awhile since i've done any math, sorry.

Maybe what you are looking for, is the following?

Collisions 1,2,3,2
;Object 1 (typically your camera, with a set radius)
colliding with type 2 objects (everything else?), with an ellipsoid to box collision (ie "3"), and slide (ie "2") as the result.

For circle-to-square collisions you can do 4 circle-to-line collisions, which you should be able to find the math for with Google painlessly.