B2.World:step
From GiderosMobile
Available since: Gideros 2011.6
Class: b2.World
Description
Takes a time step. This performs collision detection, integration, and constraint solution.
b2.World:step(timeStep,velocityIterations,positionIterations)
Parameters
timeStep: (number) the amount of time to simulate, this should not vary
velocityIterations: (number) for the velocity constraint solver
positionIterations: (number) for the position constraint solver
Examples
Creating Box2d body and moving Bitmap along the body
require "box2d"
local world = b2.World.new(0, 10, true)
--create ball bitmap object from ball graphic
local ball = Bitmap.new(Texture.new("ball.png"))
--reference center of the ball for positioning
ball:setAnchorPoint(0.5,0.5)
ball:setPosition(100,100)
--get radius
local radius = ball:getWidth()/2
--create box2d physical object
local body = world:createBody{type = b2.DYNAMIC_BODY}
local circle = b2.CircleShape.new(0, 0, radius)
local fixture = body:createFixture{shape = circle, density = 1.0,
friction = 0.1, restitution = 0.2}
ball.body = body
--add to scene
stage:addChild(ball)
stage:addEventListener(Event.ENTER_FRAME, function()
-- edit the step values if required. These are good defaults!
world:step(1/60, 8, 3)
ball:setPosition(ball.body:getPosition())
ball:setRotation(math.rad(ball.body:getAngle()))
end)
