B2.createMouseJointDef

Available since: Gideros 2011.6
Class: b2

Description

Creates and returns a mouse joint definition table with the bodies, world target point, maxForce and optional frequencyHz and dampingRatio.
(Please refer to b2.World:createJoint function for more information about all the information needed to create a mouse joint).

(table) = b2.createMouseJointDef(bodyA,bodyB,targetx,targety,maxForce,frequencyHz,dampingRatio)

Parameters

bodyA: (b2.Body) the first attached body
bodyB: (b2.Body) the second attached body
targetx: (number) the x coordinate of the world target point
targety: (number) the y coordinate of the world target point
maxForce: (number) the maximum constraint force that can be exerted to move the candidate body
frequencyHz: (number, default = 5) the response speed
dampingRatio: (number, default = 0.7) the damping ratio. 0 = no damping, 1 = critical damping

Return values

Returns (table) A new mouse joint definition table

Examples

Mouse joint

--create empty box2d body for joint
local ground = world:createBody({})

--joint with dummy body
local mouseJoint = nil

-- create a mouse joint on mouse down
function self:onMouseDown(event)
	local jointDef = b2.createMouseJointDef(ground, body, event.x, event.y, 100000)
	mouseJoint = world:createJoint(jointDef)
end

-- update the target of mouse joint on mouse move
function self:onMouseMove(event)
	if mouseJoint ~= nil then
		mouseJoint:setTarget(event.x, event.y)
	end
end

-- destroy the mouse joint on mouse up
function self:onMouseUp(event)
	if mouseJoint ~= nil then
		world:destroyJoint(mouseJoint)
		mouseJoint = nil
	end
end