Simple collision question

Blitz3D Forums/Blitz3D Beginners Area/Simple collision question

Cancerian

(Posted 2004) [#1]

Hi,

My understanding is that the "Collisions" command is required if you want to check for collisions at all in your game. The challenge is that I don't want any sort of automated response to my collisions and would rather handle it manually. Is it possible to do collision checking without initializing using the Collisions command?

For example, say I were making a 3D pong game. When the ball hits the sides of the play area or the player's paddle I want to have it rebound in the opposite direction which means I don't need the automated stop / sliding collision responses. How would I go about doing this?

Thanks for any help or advice :) Have a happy new year!

TomToad

(Posted 2004) [#2]

There are the "pick" commands, EntityPick, LinePick, CameraPick, etc...
Also you could just keep track of the x,y,z of the paddles and the ball and consider a collision when the ball's position is within a certain distance of the paddle's position.

jfk EO-11110

(Posted 2004) [#3]

There have been a perpetual discussion about this "no-response-collision". It is possible, eg. this way:

first create some collision types, eg:

BALLTYPE=1
PADTYPE=2

ball=createsphere()
entitytype ball,BALLTYPE

pad=createcube()
entitytype pad, PADTYPE

collisions BALLTYPE,PADTYPE,2,2

;--------------mainloop-----------------
while playerdidnthitescorsomething
 entitytype ball, BALLTYPE
 entitytype pad, PADTYPE
 ; controls and everything usual
 ; move bal and pad etc., then store the new position(s)
 x#=entityx(ball)
 y#=entityy(ball)
 z#=entityz(ball)
 ; now call the collsion handler
 updateworld()
 ; now you can check for collisions, eg. EntityCollided etc.
 ; after using all required collision information, do this:
 entitytype ball, 0
 positionentity ball,x,y,z ; the coords we saved before
 ; now use your own response code here!
 renderworld()
 flip
wend

big10p

(Posted 2004) [#4]

For a Pong game, I'd just set up ball collision with a 'stop' response, and then check to see if the ball has collided with anything every frame. If it has, change it's trajectory and send it on it's way again, or whatever. :)

GC-Martijn

(Posted 2004) [#5]

how to handel 2D collsion ?

I use this
If ImagesCollide(sprite1,x%,y%,a%,berg1,200,200,0)

but than the moving object is hanging in a tree.
I thought mmm then I change the x and y -1 or +1 but that's not working because you can walk arround the tree.

;some code here
wend
;some code here

Collide()

	;move
	If KeyDown(205) Then ;right
		x%=x%+1
		a%=3
	End If
	If KeyDown(203) Then ;left
		x%=x%-1
		a%=9
	End If
	If KeyDown(200) Then ;up
		y%=y%-1
		a%=0
	End If
	If KeyDown(208) Then ;down
		y%=y%+1
		a%=6
	End If

	DrawImage sprite1,x%,y%,(sprite1_frm+a%)
	
	a% = "" ;idle
Flip
Wend
End

Function Collide()
	If ImagesCollide(sprite1,x%,y%,a%,berg1,200,200,0) Then
		Text 250,250,"Now i'm stuck in a tree"
	;But I want to walk again 
	EndIf
End Function

wizzlefish

(Posted 2004) [#6]

I think he said 3D.