Basic collision handling

Audio and Graphics
#1

local function collide(event)

display.remove (event.object2)

end

Runtime:addEventListener(“collision”, collide)

That’s my basic file.  The display object include circles and rectangles falling in gravity, hitting a “static” ground.  Upon hitting the ground, they disappear.  All fine until I try to separate out the circles from the rectangles and only have circles disappear.  The objects are created in a for loop.  Is this why Corona is showing a “nil” value for their object1.myName?  Why do they disappear upon hitting the ground if they have a “nil” value?

Any help would be greatly appreciated.

#2

Would be useful to see how you’re creating your objects.

The above collision function doesn’t differentiate between objects. You might want to use an object listener instead of a Runtime listener.

 

local testBalloon = {} for i=1, 5 do testBalloon[i] = display.newCircle(96, 96, 124) testBalloon[i].name = ("testBalloon".. i) testBalloon[i].id = i testBalloon[i]:setFillColor(255,0,0) testBalloon[i].x = display.contentWidth/4+(i\*50) testBalloon[i].y = display.contentHeight/2.1+(i\*25) physics.addBody(testBalloon[i],{density=3, bounce=1.00001, shape=balloonShape}) print(testBalloon[i].name) local function testBalloonName(self, event) if event.phase == "ended" then print("Balloon name = "..self.name) self:setFillColor(0,255,0) end end local function onCollision(self, event ) if event.phase == "ended" then print("Balloon id = "..self.id) self:setFillColor(0,0,255) end end testBalloon[i].collision = onCollision testBalloon[i]:addEventListener("collision", testBalloon[i]) testBalloon[i].touch = testBalloonName testBalloon[i]:addEventListener("touch", testBalloon[i]) end
#3

Thanks Alex.  That was really helpful.  I was posting the objects in a for loop but had the listeners outside the loop.  My brain is still wrapping around how the code is compiled.

One question on some of your code… the listeners…

testBalloon[i].collision = onCollision

testBalloon[i]:addEventListener(“collision”, testBalloon[i])

testBalloon[i].touch = testBalloonName

testBalloon[i]:addEventListener(“touch”, testBalloon[i])

How come it’s necessary to declare that testBalloon[i] = onCollision?  How come you cannot simply reference onCollision straight from the addEventListener?

Thanks for your time.

#4

You could do:

testBalloon[i]:addEventListener("touch", testBallonName)

instead, but then you would lose the “self” target. You could always use event.target instead, but I prefer self as I find it more flexible. 

#5

Would be useful to see how you’re creating your objects.

The above collision function doesn’t differentiate between objects. You might want to use an object listener instead of a Runtime listener.

 

local testBalloon = {} for i=1, 5 do testBalloon[i] = display.newCircle(96, 96, 124) testBalloon[i].name = ("testBalloon".. i) testBalloon[i].id = i testBalloon[i]:setFillColor(255,0,0) testBalloon[i].x = display.contentWidth/4+(i\*50) testBalloon[i].y = display.contentHeight/2.1+(i\*25) physics.addBody(testBalloon[i],{density=3, bounce=1.00001, shape=balloonShape}) print(testBalloon[i].name) local function testBalloonName(self, event) if event.phase == "ended" then print("Balloon name = "..self.name) self:setFillColor(0,255,0) end end local function onCollision(self, event ) if event.phase == "ended" then print("Balloon id = "..self.id) self:setFillColor(0,0,255) end end testBalloon[i].collision = onCollision testBalloon[i]:addEventListener("collision", testBalloon[i]) testBalloon[i].touch = testBalloonName testBalloon[i]:addEventListener("touch", testBalloon[i]) end
#6

Thanks Alex.  That was really helpful.  I was posting the objects in a for loop but had the listeners outside the loop.  My brain is still wrapping around how the code is compiled.

One question on some of your code… the listeners…

testBalloon[i].collision = onCollision

testBalloon[i]:addEventListener(“collision”, testBalloon[i])

testBalloon[i].touch = testBalloonName

testBalloon[i]:addEventListener(“touch”, testBalloon[i])

How come it’s necessary to declare that testBalloon[i] = onCollision?  How come you cannot simply reference onCollision straight from the addEventListener?

Thanks for your time.

#7

You could do:

testBalloon[i]:addEventListener("touch", testBallonName)

instead, but then you would lose the “self” target. You could always use event.target instead, but I prefer self as I find it more flexible.