Alternative Collision

BlitzPlus Forums/BlitzPlus Programming/Alternative Collision

En929

(Posted 2011) [#1]

I'm think there is an alternative way to do collisions. For collisions, I usually use the "If ImagesCollide" or "If ImageRectCollide" commands, but I think that there's another way to do collisions that involves some type of mathematical formula (I saw it in the "Programming for Teens" book but I don't remember it - and I don't have the book).

But, I would like practice at one like that one so that if I decide to learn another programming language I'll know how to do it in that language too. Thus, can someone tell me what it is? Thanks.

Moore

(Posted 2011) [#2]

You could calculate the distance between objects and if that is less then their combined collision radius then you would have a collision.

Type game_object
 Field x, y, col_radius
End Type

Function collision(a.game_object, b.game_object)
 If dist(a, b) <= a\col_radius + b\col_radius then return True
 Return False
End Function

Function dist(a.game_object, b.game_object)
 d = Sqr(((b\y - a\y)^2) + ((b\x - a\x) ^ 2))
 Return d
End Function

Matty

(Posted 2011) [#3]

I've answered your post in the blitz3d forums.

Do you really need to post the same question in multiple sections of the blitz forums - it puts me off (and perhaps others) answering when they go to the effort of answering in one thread only to find that you've asked it elsewhere as well...

En929

(Posted 2011) [#4]

I'm sorry Matty. Sometimes the 3d forums tends to be more active. Thus, it is why I posted my question there too (I probably should have simply posted a link to this page when I posted the question in the 3d forum so they can simply answer my question here (or so). I got your response there. Thanks.

Also, thanks Moore. I'll try that. When I get it, I may be using that collision method from now on.

Last edited 2011

En929

(Posted 2011) [#5]

Moore, I'm interested in the code you wrote. Can you write that into my game program below and make it so that the "PLAYER" character can collide with the "DOOR." I tried to use the code that you wrote, but I failed. Thus, I'd like to see an example of it being used in what I wrote below so I can use it from then on. Thanks.



Graphics 1640, 1000 


PLAYER = LoadImage ("Ball.png")
DOOR = LoadImage ("Door.png")



Type PLAYER 
	Field x,y
End Type

Type DOOR	
	Field x,y
End Type




p.PLAYER = New PLAYER
p\x = 500
p\y = 250

d.DOOR = New DOOR
d\x = 500
d\y = 250



While Not KeyDown(1)

   Cls 


;-------------------------Alternative Collision code-----------------------
; would like  to see the alternative collision code being used
;here with the two characters loaded above (e.g. the PLAYER 
;and DOOR characters) so that I can follow how they're used. Thanks.






											







;-------------------------------------------------------------------------------------------




   If KeyDown(208)
      p\y = p\y + 3
   EndIf 


   If KeyDown(200)
      p\y = p\y - 3
    EndIf 


   If KeyDown(205)
      p\x = p\x + 3
   EndIf 


   If KeyDown(203)
      p\x = p\x - 3
   EndIf 


DrawImage (DOOR,d\x,d\y)
DrawImage (PLAYER,p\x,p\y)

	

   Flip

Wend

Last edited 2011

Last edited 2011