Hi, I’m trying to make a magnet, but it’s just not working. I’m using (http://www.coronalabs.com/blog/2013/04/09/physics-radial-gravity-and-predicting-trajectory/)]this site as my guide. But for some reason, it’s just not acting on my object. What did I do wrong? That part that should be affecting gravity starts at line 146.
This is my code:
[lua]
local physics = require(“physics”)
physics.start()
physics.setGravity(0, 0)
physics.setScale( 10 )
physics.setDrawMode( “normal” )
local magnetPull = 0.25
local n = 0
m = {}
m.random = math.random
–local state = display.newGroup()
local force_multiplier = ( 10 )
local velocity = m.random(50,100)
–Hiding status bar
display.setStatusBar( display.HiddenStatusBar )
– Setting background color
display.setDefault( “background”, 100,255,250 )
–code for gravity field
–Code for balls teehee
local Ball = display.newImage(“Ball.png”)
–boundries
–left side
local boundryLeft = display.newRect(-42, 0, 5, 480)
boundryLeft.strokeWidth = 5
boundryLeft:setFillColor( 0, 0, 0 )
boundryLeft:setStrokeColor( 0, 0, 0 )
physics.addBody( boundryLeft, “static” )
–top
local boundryTop = display.newRect( -42, 0, 640, 5 )
boundryTop.strokeWidth = 5
boundryTop:setFillColor( 0, 0, 0 )
boundryTop:setStrokeColor( 0, 0, 0 )
physics.addBody( boundryTop, “static” )
–right side
local boundryRight = display.newRect( 520, 0, 5, 480 )
boundryRight.strokeWidth = 5
boundryRight:setFillColor( 0, 0, 0 )
boundryRight:setStrokeColor( 0, 0, 0 )
physics.addBody( boundryRight, “static” )
–bottom
local boundryBottom = display.newRect( -42, 315, 640, 5 )
boundryBottom.strokeWidth = 5
boundryBottom:setFillColor( 0, 0, 0 )
boundryBottom:setStrokeColor( 0, 0, 0 )
physics.addBody( boundryBottom, “static” )
Ball.x = 200
Ball.y = 250
physics.addBody( Ball, “static” )
local Ball2 = display.newImage(“Ball.png”)
Ball2.x = 200
Ball2.y = 50
physics.addBody( Ball2, “static” )
–code for gravity field
local field = display.newCircle( 0, 0, 100 ) ; field.alpha = 0.3
field.name = “field”
field.x = Ball2.x ; field.y = Ball2.y
physics.addBody( field, “static”, { isSensor = true, radius = 100 } )
local PlayerChar = display.newImage( “PlayerChar.png”)
PlayerChar.x = 50
PlayerChar.y = 160
physics.addBody( PlayerChar, PlayerCharBody )
PlayerChar.linearDamping = 0.3
PlayerChar.angularDamping = 0.8
PlayerChar.isBullet = true --force continue collision detection to stop really fast shots from breaking things
PlayerCharBody = { density=0.8, friction=1, bounce=0, radius=15 }
target = display.newImage( “target.png” )
target.x = PlayerChar.x; target.y = PlayerChar.y; target.alpha = 0
–firing
local function shot( event )
local t = event.target
local phase = event.phase
if “began” == phase then
display.getCurrentStage():setFocus( t )
t.isFocus = true
--stop current ball motion, if any
t:setLinearVelocity( 0, 0 )
t.angularVelocity = 0
target.x = t.x
target.y = t.y
startRotation = function()
target.rotation = target.rotation + 4
end
Runtime:addEventListener( “enterFrame”, startRotation )
local showTarget = transition.to( target, { alpha = 0.4, xScale=0.4, yScale=0.4, time=200 } )
myLine = nil
elseif t.isFocus then
if “moved” == phase then
if( myLine ) then
--myLine.parent:remove( myLine )
display.remove(myLine)
print(“myLine removed”)
end
myLine = display.newLine( t.x, t.y, event.x, event.y )
myLine:setColor( 255, 255, 255, 50 )
myLine.width = 8
print(“myLine added”)
elseif “ended” == phase or “cancelled” == phase then
Runtime:removeEventListener( “enterFrame”, startRotation )
if( myLine ) then
--myLine.parent:remove( myLine )
display.remove(myLine)
print("–myLine removed")
end
--move the PlayerChar…
t:applyForce( (t.x - event.x), (t.y - event.y), t.x, t.y )
end
local hideTarget = transition.to( target, { alpha=0, xScale=1.0, time=200, onComplete=stopRotation } )
end
return true
end
–magnet/gravity
function objectCollide( self, event )
local otherName = event.other.name
local function onDelay( event )
local action = “”
if ( event.source ) then
action = event.source.action
timer.cancel( event.source )
end
if ( action == “makeJoint” ) then
self.hasJoint = true
self.touchJoint = physics.newJoint( “touch”, field, field.x, field.y )
self.touchJoint.frequency = 0.25
self.touchJoint.dampingRatio = 0.0
self.touchJoint:setTarget( Ball2.x, Ball2.y )
print( “done” )
end
end
if ( event.phase == “began” and otherName == “field” and self.hasJoint == false ) then
local tr = timer.performWithDelay( 10, onDelay )
tr.action = ( “makeJoint” )
print( “joint made” )
end
end
PlayerChar:addEventListener( “touch”, shot )
local function resetPlayerChar()
PlayerChar:setLinearVelocity( 0, 0 )
PlayerChar.alpha = 0
PlayerChar.x = 50
PlayerChar.y = 160
local dropPlayerChar = transition.to( PlayerChar, { alpha=1.0, xScale=1.0, yScale = 1.0, time=1000 } )
end
function onCollision( event )
print( “reset” )
--timer.performWithDelay( 50, resetPlayerChar )
end
PlayerChar:addEventListener( “collision”, onCollision )
[/lua]