Physics contact test

local physics = require "physics"

local floor = display.newRect(0, display.contentCenterY, display.contentWidth, 30)

local ball = display.newGroup()
ball.x, ball.y = 20, display.contentCenterY - 20
display.newCircle(ball, 0, 0, 20)
display.newRect(ball, -8, -8, 16, 16)
    :setFillColor(0x00)

physics.start()

physics.addBody(floor, 'static')
physics.addBody(ball, 'dynamic', {radius=20})

physics.setGravity(1, 9.8)

physics.setReportCollisionsInContentCoordinates(true)

floor:addEventListener('preCollision',
    function(event)
        print(event.x, event.y)
    end
)