How to use Weldjoints

[kloki]

Im trying glue object together using the weld joints. My goal is to add specific sensors to a main collision box. This way I can use collision callback to register head collision, foot collisions etc. The problem is I cant seem to get the weldjoints to work. I tried the wiki but the documentation is kind of sparse.

Below is the code how I initialize everything. At the moment the two objects act as if they are not connected. What am I doing wrong? I think I got the anchors right.

Code: Select all

   
   self.body = love.physics.newBody(gameworld,self.x,self.y,"dynamic")
   self.shape = love.physics.newRectangleShape(32,64)
   self.fixture = love.physics.newFixture(self.body,self.shape,1)
   self.fixture:setUserData("player")
   self.body:setFixedRotation( true )  
   self.fixture:setRestitution(0.1)
   
   --foot sensor
   self.footsensor={}
   self.footsensor.body = love.physics.newBody(gameworld,self.x,self.y+33,"dynamic")
   self.footsensor.shape = love.physics.newRectangleShape(20,2)
   self.footsensor.fixture = love.physics.newFixture(self.footsensor.body,self.footsensor.shape,1)
   self.footsensor.fixture:setUserData("playerfoot")
   self.footsensor.body:setFixedRotation( true )
   self.footsensor.fixture:setSensor(true)

   --weldjoint
   self.footjoint=love.physics.newWeldJoint(self.body,self.footsensor.body,16,63,10,1,false)

[Boolsheet]

I'm not sure, but I think Box2D just skips the sensor fixture when it tries to apply constraints and that makes it a body without fixtures and shapes. Can't you just add the sensor fixture to the main body instead of giving it its own? Bodies can have multiple fixtures attached to them. You also don't have to involve the soft WeldJoint that way.

[juno]

Boolsheet is right.
You don't need to use weld joints in your case. Try something like:

Code: Select all

self.body = love.physics.newBody(gameworld,self.x,self.y,"dynamic")
   self.shape = love.physics.newRectangleShape(32,64)
   self.fixture = love.physics.newFixture(self.body,self.shape,1)
   self.fixture:setUserData("player")
   self.body:setFixedRotation( true )  
   self.fixture:setRestitution(0.1)
   
   self.footShape = love.physics.newRectangleShape( 0, 33, 20,2, 0 )
   self.footFixture = love.physics.newFixture(self.body,self.footShape,1)
   self.footFixture:setUserData("playerfoot")

The collision callbacks will be triggered with whatever body part is colliding.

[kloki]

I didn't know you could do that. This is good to know Works Perfect