Box2d "On landed" event

Comments

• totebo Member

  September 2016

  Make it bouncy! When you create the fixture of the square body, set restitution to a higher value.
  

  My Gideros games: www.totebo.com

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• rrraptor Member

  September 2016

  Its bouncing already. I need that "on landed" event\check.

  SuperShape | Nice blured shapes with shadows | Simple button pad | Simple layer class | Simple UI library | 2D camera lib | Color picker | FPS graph | Dear ImGui | cute_c2

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• antix Member

  September 2016

  Maybe you could add a sensor fixture to your objects?

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• totebo Member

  September 2016

  Yeah, you're going to have to listen to collision events, then check that the square body is colliding with the floor body.
  
  http://docs.giderosmobile.com/reference/physics/b2World/Event.BEGIN_CONTACT#Event.BEGIN_CONTACT

  My Gideros games: www.totebo.com

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• rrraptor Member

  September 2016 edited September 2016

  @totebo walls is moving around, so the player can collide with them from left, top, bottom and right. So, "BEGIN_CONTACT" didnt help much...but i can try add some checks.
  P.S. I know about docs, and use them actively.
  @antix nah, workaround

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• totebo Member

  September 2016 edited September 2016

  Yeah, you'd have to identify each fixture/body and use that ID in the check. The way I do that is using RUBE for the level design and assign each fixture/body a name I check against.
  
  This method is a little messy, but I think it's the only way to do it in Box2D. If your game doesn't require rotated objects or polygons, I would very much recommend to use Bump instead of Box2D. It's a lot faster and collisions are handled in a simpler way.

  My Gideros games: www.totebo.com

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• tkhnoman Member

  September 2016 edited September 2016 Accepted Answer

  For landing event, you can check the contact vector at BEGIN_CONTACT on:
  event.contact:getManifold().localNormal
  
  At there, check whether y indicate 1 (or -1 depends on which is fixtureA)
  If your object touch slanted object (or circle), y would produce between 1 to 0, so make sure you get y>0.1 value, or such to detect landing event.
  
  You can also get contact point with event.contact:getWorldManifold().points[1]
  if it is somehow needed in calculation.
  
  Not forget to mention, these are only working for non-sensor box2d object.

  Likes: totebo, rrraptor

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• rrraptor Member

  September 2016

  @tkhnoman ty. By using this method i can detect any other side, right?

  SuperShape | Nice blured shapes with shadows | Simple button pad | Simple layer class | Simple UI library | 2D camera lib | Color picker | FPS graph | Dear ImGui | cute_c2

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• tkhnoman Member

  September 2016

  Yes you can.
  
  You can also use rayCast & queryAABB to help the detection on contact, if somehow it need a complex one.

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