display.setStatusBar( display.HiddenStatusBar )
 
local physics = require("physics")
physics.start()
physics.setGravity( 0, 9.81)  -- 9.81 m/s*s in the positive x direction  
physics.setScale(200)  -- 200 pixels per meter
 
local background = display.newImage("bg.png")
 
local ground = display.newImage("ground.png")
ground.y = 310
physics.addBody( ground, "static", { friction = 1.0, bounce = 0.6, density = 1.0 } )
 
local ballBody = { density=0.8, friction=0.3, bounce=0.1, radius=18 }
local ball = display.newImage("black.png")
ball.x = 25
ball.y = 60
ball.linearDamping = 0.3
ball.angularDamping = 0.8
physics.addBody( ball, ballBody )
 
local ramp = display.newImage("ramp.png")
ramp.x = 40
ramp.y = 290
ramp.rotation = 30
physics.addBody( ramp, "static", { friction = 1.0, bounce = 0.0, density = 1.0 } )
ramp.isPlatform = true
 
local ramp1 = display.newImage("ramp.png")
ramp1.x = 90
ramp1.y = 290
ramp1.rotation = 170
physics.addBody( ramp1, "static", { friction = 1.0, bounce = 0.0, density = 1.0 } )
ramp1.isPlatform = true
 
local function startDrag( event )
        local t = event.target
 
        local phase = event.phase
        if "began" == phase then
                display.getCurrentStage():setFocus( t )
                t.isFocus = true
 
                -- Store initial position
                t.x0 = event.x - t.x
                t.y0 = event.y - t.y
                
                -- Make body type temporarily "kinematic" (to avoid gravitional forces)
                event.target.bodyType = "kinematic"
                
                -- Stop current motion, if any
                event.target:setLinearVelocity( 0, 0 )
                event.target.angularVelocity = 0
 
        elseif t.isFocus then
                if "moved" == phase then
                        t.x = event.x - t.x0
                        t.y = event.y - t.y0
 
                elseif "ended" == phase or "cancelled" == phase then
                        display.getCurrentStage():setFocus( nil )
                        t.isFocus = false
                        
                        -- Switch body type back to "dynamic", unless we've marked this sprite as a platform
                        if ( not event.target.isPlatform ) then
                                event.target.bodyType = "dynamic"
                        end
 
                end
        end
 
        -- Stop further propagation of touch event!
        return true
end
 
ramp:addEventListener( "touch", startDrag )
ramp1:addEventListener( "touch", startDrag )