Creating a explosion

Physics
#1

So guys i’m trying to create a explosion in my game, a found a tutorial and come up with this:

local function exploLission ( self, event) print(event.other.type) print(self.type) if(event.phase == "began") then local forcex = event.other.x-self.x local forcey = event.other.y-self.y-20 if(forcex \< 0) then forcex = 0-(60 + forcex)-12 else forcex = 60 - forcex+12 end event.other:applyForce( forcex, forcey, self.x, self.y ) end end local circle = display.newCircle( -100, -100, 60 ) physics.addBody(circle, "static", {isSensor = true, filter = filtroExplosoes}) circle.type = "circle" group:insert(circle) circle.collision = exploLission circle:addEventListener("collision", circle) local function criarExplosao(cirx, ciry) circle.x = cirx circle.y = ciry end criarExplosao(100, 100)

In my collision detector ( exploLission ), i manage to print out, the type of my circle, and the type of the other object, so the collision is being detected, but for some reason the event.other:applyforce, is being complete ignored.

event.other is a object in transition.to() does this matter?

#2

Yes, it does matter if the transition is affecting the object’s position. You shouldn’t apply transitions to the positions of physics object, because the physics engine needs to ‘own’ the object. If the transition is affecting some other property of the object, like alpha, then it won’t matter. You might also try applying a larger force. Maybe it appears nothing is happening simply because the force is too small. - Andrew

#3

Here’s some sample code for explosions that might be a bit cleaner:

 local function createStar() local starSpeed = 10 local starTime = 1200 local powerUpRandom = math.random timer.performWithDelay(10, function() local starDown = display.newRect(0,0,10,10) starDown:setFillColor(255,235,0) physics.addBody( starDown, "dynamic",{ density = 3.0, isSensor=true } ) starDown:applyForce(2\*(powerUpRandom(starSpeed\*-1,starSpeed)),2\*(powerUpRandom(starSpeed\*-1,starSpeed)), starDown.x\*(powerUpRandom(1,10)), starDown.y\*(powerUpRandom(1,10))) starDown:applyTorque(3\*powerUpRandom(25,35)) starDown.x = 100 starDown.y = 100 game7:insert(starDown) transition.to(starDown, {time=starTime, alpha=.1}) return starDown end, 15) end

That’s kind of an easy standalone snippet that generates an explosion type animation. Hope it helps!

#4

Yes, it does matter if the transition is affecting the object’s position. You shouldn’t apply transitions to the positions of physics object, because the physics engine needs to ‘own’ the object. If the transition is affecting some other property of the object, like alpha, then it won’t matter. You might also try applying a larger force. Maybe it appears nothing is happening simply because the force is too small. - Andrew

#5

Here’s some sample code for explosions that might be a bit cleaner:

 local function createStar() local starSpeed = 10 local starTime = 1200 local powerUpRandom = math.random timer.performWithDelay(10, function() local starDown = display.newRect(0,0,10,10) starDown:setFillColor(255,235,0) physics.addBody( starDown, "dynamic",{ density = 3.0, isSensor=true } ) starDown:applyForce(2\*(powerUpRandom(starSpeed\*-1,starSpeed)),2\*(powerUpRandom(starSpeed\*-1,starSpeed)), starDown.x\*(powerUpRandom(1,10)), starDown.y\*(powerUpRandom(1,10))) starDown:applyTorque(3\*powerUpRandom(25,35)) starDown.x = 100 starDown.y = 100 game7:insert(starDown) transition.to(starDown, {time=starTime, alpha=.1}) return starDown end, 15) end

That’s kind of an easy standalone snippet that generates an explosion type animation. Hope it helps!