Spawn (Boom) when Collisioin

hi

my English is weak so be gentle with me :)

i want to spawn a(Boom) when this the shape collision to a wall.

but the the (Boom) will spawn between the wall and the shape.

i have no clue where i should start so please Help me.

<img src="http://s1.postimg.org/jsjwp6o5r/Untitled.png" border="0" />

Create object with desired size. Object A

Change its polygon shape points to adhere your needs.

Add sprites for walls, leave original polygons.

Eventsheet

event: object A on collision with Walls

action1: object A spawn boom object

action2: destroy object A

Thats the gist of it

i use TiledBackground for Walls and it have sold and physics behavior .

i need to spawn (boom) sprite when the object A collision with A wall

but i need to spawn it between the object and the wall.

you know what i mean?

it's like u have tennis ball full of ink and when it hit a wall it leave a mark of ink from the ball

got it?

comoon guys , any one know how to do it?

lets say i have a shape have 4 image points (up , down , left , right)

i want to spawn sprite from image point when THAT image point collision to wall (1 image point)