How to get collision in box2d?

Comments

• Holonist Member

  March 2017 edited March 2017

  Found out how to detect collision by looking at one of the tutorials.
  
  To access the sprite, you can actually set a back-reference to it in the body.

  ball.body = self.physics:createBody{type = b2.DYNAMIC_BODY} ball.body:setPosition(ball:getPosition()) ball.body:setAngle( ball:getRotation() * math.pi/180 ) <color="red">ball.body.parent = ball</color>

  To get the sprite, you can:
  - get fixture
  - get body from fixture
  - get parent from body, which we did set above

  self.physics:addEventListener(Event.BEGIN_CONTACT, function(e) local fixtureA = e.fixtureA local fixtureB = e.fixtureB local bodyA = fixtureA:getBody() local bodyB = fixtureB:getBody()   bodyB.parent:setRotation(bodyA.parent:getRotation()) end)

  Note that this is not usually needed if you do something with physics!
  
  But it my case it was. Now if someone wants to know why, here's an awful video :'D
  The guy's body is a ball, and the sprite is not synced with the ball's rotation (obviously). But the guy's sprite orientation should be synced with the surface's rotation.
  
  
  
  Just for fun, what happens IF the guy's rotation is synced with his body
  

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• totebo Member

  March 2017

  Welcome to the world of physics! I use collision data all the time, and, in fact, built an entire game dependent on collisions; Scrappy Cat.
  
  It takes a little getting used to, because you get collisions for all fixtures at the same time. It takes a little filtering to use them.

  Likes: Holonist, antix

  My Gideros games: www.totebo.com

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