In below mentioned code, what exactly is the difference between sprite
, body
and ground
? Why are there no parameters passes to createBody
while declaring ground
?
what is difference between edgeshape.new()
and polygonshape.new()
?
require "box2d"
b2.setScale(20)
-- this function creates a box sprite with 2 happy and sad children
local function createBoxSprite(sx, sy)
local happy = Bitmap.new(Texture.new("happy-box.png", true))
happy:setAnchorPoint(0.5, 0.5)
local sad = Bitmap.new(Texture.new("sad-box.png", true))
sad:setAnchorPoint(0.5, 0.5)
local sprite = Sprite.new()
sprite:addChild(happy)
sprite:addChild(sad)
sprite:setScale(sx, sy)
return sprite
end
-- this table holds the dynamic bodies and their sprites
local actors = {}
-- create world
local world = b2.World.new(0, 9.8)
-- create a ground body and attach an edge shape
local ground = world:createBody({})
local shape = b2.EdgeShape.new(-200,480,520,480)
ground:createFixture({shape = shape, density = 0})
-- every 3 seconds, we create a random box
local function onTimer()
local sx = math.random(70, 100) / 100
local sy = math.random(70, 100) / 100
local body = world:createBody{type = b2.DYNAMIC_BODY, position = {x = math.random(0, 320), y = -35}}
local shape = b2.PolygonShape.new()
-- box images are 70x70 pixels. we create bodies 1 pixel smaller than that.
shape:setAsBox(34.5 * sx, 34.5 * sy)
body:createFixture{shape = shape, density = 1, restitution = 0.1, friction = 0.3}
local sprite = createBoxSprite(sx, sy)
stage:addChild(sprite)
actors[body] = sprite
end