碰撞事件对应捕捉与处理实例

function love.load()
--create a new world
world = love.physics.newWorld(0,200,true)
--These callback function names can be almost any you want:
world:setCallbacks(beginContact,endContact,preSolve,postSolve)
-- we'll use this to put info text on the screen later
text       = ""
-- we'll use this to store the state of repeated callback calls

    persisting = 0

--create a ball with bouncy
ball = {}

ball.b = love.physics.newBody(world, 400,50,"dynamic")
ball.b:setMass(10)

ball.s = love.physics.newCircleShape(20)
ball.f = love.physics.newFixture(ball.b,ball.s)
ball.f:setRestitution(0.4)
ball.f:setUserData("BALL")

--
static = {}

static.b  = love.physics.newBody(world,400,400,"static")

static.s = love.physics.newRectangleShape(200,50)
static.f = love.physics.newFixture(static.b,static.s)
static.f:setUserData("STATIC")

end

function love.update(dt)
--let the world have the update event
world:update(dt)

if love.keyboard.isDown("right") then

        ball.b:applyForce(1000, 0)

    elseif love.keyboard.isDown("left") then

        ball.b:applyForce(-1000, 0)

    end

    if love.keyboard.isDown("up") then

        ball.b:applyForce(0, -5000)

    elseif love.keyboard.isDown("down") then

        ball.b:applyForce(0, 1000)

    end

if string.len(text) > 768 then    -- cleanup when 'text' gets too long

        text = ""

    end

end

function love.draw()
--画圆
love.graphics.setColor(255,0,0)
love.graphics.circle("fill", ball.b:getX(),ball.b:getY(), ball.s:getRadius(), 20)
--画矩形
love.graphics.setColor(0,255,0)

    love.graphics.polygon("fill", static.b:getWorldPoints(static.s:getPoints()))

love.graphics.print(text, 10, 10)

end

--a is the first fixture object in the collision.

--b is the second fixture object in the collision.

--coll is the contact object created.

function beginContact(a,b,coll)

x,y = coll:getNormal()

    text = text.."\n"..a:getUserData().." crashing with "..b:getUserData().." with a vector normal of: "..x..", "..y

end

function endContact(a,b,coll)

persisting = 0    -- reset since they're no longer touching

    text = text.."\n"..a:getUserData().." uncolliding with "..b:getUserData()

end

function preSolve(a,b,coll)
-- only say when they first start touching
if persisting == 0 then

        text = text.."\n"..a:getUserData().." touchin-- only say when they first start touchingg "..b:getUserData()

    elseif persisting < 20 then    -- then just start counting

        text = text.." "..persisting

    end

    persisting = persisting + 1    -- keep track of how many updates they've been touching for

end

function postSolve(a,b,coll)

end