B2.MouseJoint

Supported platforms:
Available since: Gideros 2011.6
Inherits from: b2.Joint

Description

A mouse joint is used to make a point on a body track a specified world point. This a soft constraint with a maximum force. This allows the constraint to stretch and without applying huge forces.

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

Methods b2.MouseJoint:getDampingRatio returns the damping ratio b2.MouseJoint:getFrequency returns the response frequency in Hertz b2.MouseJoint:getMaxForce returns the maximum force in N b2.MouseJoint:getTarget returns the x and y coordinates of the target point b2.MouseJoint:setDampingRatio sets the damping ratio (0 = no damping, 1 = critical damping) b2.MouseJoint:setFrequency sets the response frequency in Hertz b2.MouseJoint:setMaxForce sets the maximum force in N b2.MouseJoint:setTarget updates the target point

Events Constants