How to make my mouseUp event work only when I click on the enemy?

AxlFlame · January 2013

Hi,
I'm creating a game where basically if the player clicks on an enemy, the enemy is destroyed. My problem here is, the way I coded, regardless of where the player clicks, the enemy is destroyed and I wanted that to happen only when the player clicks on the enemy. How can I make that happen?
Thanks in advance!
This is the enemy class (bDobstaculos.lua)

bDobstaculos = gideros.class(Bitmap);
 
 
function bDobstaculos:init(text, xPos, yPos, b2World)
	self:setAnchorPoint(0.5, 0.5);
	self.body = b2World:createBody{
				type = b2.STATIC_BODY, 
				position = {x = 400, y = 140},
				fixedRotation = true,
				allowSleep = false;
				active = true,
				gravityScale = 1
			};
	self.body.name = "spike";
	local shapeSpike = b2.PolygonShape.new()
	shapeSpike:setAsBox(25, 40)
	self.fixture = self.body:createFixture{shape = shapeSpike,
				friction = 0,
				restitution = 0,
				density = 30,
				isSensor = true
				};
	self:setPosition(xPos, yPos-self:getHeight()*0.5);
end
 
function bDobstaculos:addListeners()
	self:addEventListener(Event.ENTER_FRAME, self.onEnterFrame, self);
	self:addEventListener(Event.MOUSE_UP, self.apagaInimigo, self);
end
 
function bDobstaculos:removeListeners()
	self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame, self);
end
 
function bDobstaculos:onEnterFrame()
	self.body:setPosition(self:getPosition());
	local b2World = self.moveMe(self);
	if self:getX() < -50 then
		self.fixture = nil;
		b2World:destroyBody(self.body);
		self.body = nil;
		self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame, self);
		self:getParent():removeChild(self);
	end
end
 
function bDobstaculos:apagaInimigo()
	self.fixture = nil;
	b2World:destroyBody(self.body);
	self.body = nil;
	self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame, self);
	self:getParent():removeChild(self);	
end

thanhquan1512 · January 2013

1. In function bDobstaculos:apagaInimigo(), using hitTestPoint() to check if mouse event is in bound of enemy sprite:
http://www.giderosmobile.com/documentation/reference_manual.html#Sprite:hitTestPoint

if enemySprite:hitTestPoint(event.x, event.y) then
--destroy enemy
end

2.self:getParent():removeChild(self)

you should use:

self:removeFromParent()

OZApps · January 2013

@AxlFlame,

if you want to really make the app 100% proper, then you will have to first check that your touch started on the enemy and the touch ended on the enemy. It might not be important in your app, but what happens if the player start the touch with the friendly unit and then ends it on the enemy? If that is important to you, you might want to also listen for Mouse_Down, not just mouse_up.

OZApps · January 2013

a similar discussion can be found at http://giderosmobile.com/forum/discussion/2585/over-lapping-touches#Item_2

AxlFlame · February 2013

Thanks for the answers, guys! But I have a problem with the hitTestPoint function.
See, this bDobstaculos.lua is called inside my main game function to create the enemy, but the created enemy is local, so I changed it to global and the code inside the apagaInimigo() is like this:

function bDobstaculos:apagaInimigo()
	if enemy:hitTestPoint(Event.x, Event.y) then
		self.fixture = nil;
		b2World:destroyBody(self.body);
		self.body = nil;
		self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame, self);
		self:getParent():removeChild(self);	
	end
end

Where enemy is the name for the created enemy sprite on my main game. (Since it's global, I tried calling it with _G.enemy, but it didn't work.
The point is that this code is giving me this error:

bad argument #1 to 'hitTestPoint' (number expected, got nil)

Why isn't it getting the x and probably the y? Am I on the right track, as least?

@OzApps
I haven't actually thought about that! It sure is important for me that the click starts and ends within the enemy sprite, but I thought it would be best for now to focus on making the MOUSE_UP work, since even that isn't and I didn't quite grasped the idea of the discussion you pointed out...

BJG · February 2013

Have you defined "Event.x" and "Event.y"...?

Check out the "Drag Me" example in the demos. The usual syntax is more like...

local function onMouseDown(self, event)
	if self:hitTestPoint(event.x, event.y) then

AxlFlame · February 2013

Yeah, I was about to post here that I found out it was a sintax error and the undefined event... I feel so dumb lol

I did like you said and it finally worked!

function bDobstaculos:apagaInimigo(event)
	if enemy:hitTestPoint(event.x, event.y) then
		self.fixture = nil;
		b2World:destroyBody(self.body);
		self.body = nil;
		self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame, self);
		self:getParent():removeChild(self);	
	end
end

Thanks a lot, guys!

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