How to know which collision object is colliding with other?

Questions
1

I have a enemy with 3 collision objects and i want to do different actions depending on which collision object is detecting the collision. How i do that?

And another question. Is possible to stop detecting the collisions of a specific group? For example, when my main character is dead, then he stops detecting the collision with group “enemies” but not with group “terrain”.

2

The url to the collisionobject that has detected the collision will be available in the sender parameter of on_message. You can also check the property message.group to see which group has triggered the collision.
To stop detecting collisions on an object, simply send a disable message to it, so:

function on_message(self, message_id, message, sender)
  if sender==msg.url("#collisionobject") then
    --do something
    msg.post(sender, "disable")
  end
end
4 Likes
3

ok, thank you for your help!

4

other question, you know if it possible to disable a specific mask? instead of disable the whole collision object

5

No, you would need to do that manually. Set allt he masks that the object would collide with at any point, and then in code do something like:

function init(self)
  self.mask={
    [hash("ground")]=true,
    [hash("enemy")]=true
  }
end

function on_message(self, message_id, message, sender)
  if message_id==COLLISION_RESPONSE and mask[message.group] then
    --do collision logic
    self.mask[message.group]=false
  end
end
2 Likes
6

ok, thank you again :smile: