Modifying an Image after Collision

Games
#1

I am having problems changing the Image of an object after a collision.

Purpose is to change the image of a block to the image of a damaged block after colliding with an enemy.

I have a function:

newShape ( kind, x, y, health )

if ( kind == 1 ) then

if ( health == 2 ) then

shape = display.newRect ( xxxxx );
shape.health = 2;
localGroup:insert ( shape );
physic.addBody ( shape, {xxx} );

elseif ( health == 1 ) then

shape = display.newRect ( xxxxx );
shape.health = 1;
localGroup:insert ( shape );
physic.addBody ( shape, {xxx} );

end

end

end

so that is how I am creating my shapes, they are then stored in a table:

local shapeObjects = {}

shapeObject[i] = newShape ( kind, x, y, health );
shapeObject[i].index = i;

and then I have a collision:

function onCollision ( self, e )

if ( e.phase == “began” ) then

timer.performWithDelay ( 100, updateHealth ( e.other, self );

end

end

enemy.collision = onCollision;
enemy:addEventListener ( “collision”, enemy );

The collision outsources to another function which controls the image swapping

function updateHealth ( shape, enemy )

local health = shape.health - enemy.damage;
local index = shape.index;
local kind = shape.kind;
local x = shape.x;
loca; y = shape.y;

if ( health > 0 ) then

shape:removeSelf ();

– Here is where the program is having a problem and crashes.

shapeObject[index] = newShape ( kind, x, y, health );

elseif ( health >= 0 ) then

shape:removeSelf ();

end

end

So I can remove that line of code and everything works fine. I have also tried having the program create a simple rectangle of a new name:

tempShape = display.newRect ( xxxx );

But if I try to add it to a group or add it as a physical body, the program crashes.
I read that you have to have a timer delayed to make modification or remove objects during a collision, but I have done this and still every time it crashes and I have tried almost everything.

Any ideas on an alternative or a fix to my problem

[import]uid: 59590 topic_id: 17523 reply_id: 317523[/import]

#2

Assuming your box isn’t animated, I suggest combining the two images in a sprite sheet, then making the box a one-frame sprite. That way you can use sprite:prepare to change the box to the damaged image frame. [import]uid: 89724 topic_id: 17523 reply_id: 66556[/import]

#3

Ill try this and let you know [import]uid: 59590 topic_id: 17523 reply_id: 66559[/import]

#4

A good solution is in your object-creation function, create and return a group that has two children, for instance, group.default and group.collided (which will be references to two display objects inserted into that group).

Then, when your object collides, you could do something like:

group.default.isVisible = false group.collided.isVisible = true[/code]Hope that helps get you moving in the right direction—good luck! [import]uid: 52430 topic_id: 17523 reply_id: 66582[/import]

#5

Jonathan’s method is also much better for animated sprites, since the prepare method has a noticeable delay and doesn’t look good when transitioning an animated sprite onscreen. [import]uid: 89724 topic_id: 17523 reply_id: 66586[/import]