i want to access attributes of the objects, that sth. collided with.
so inside the "function on_message(self, message_id, message, sender)"
i try to handle it:
so far i can only access the other_id with an if statement like:
if message.other_id == hash ("/spaceship") then
the problem is, that objects spawned by factories have artifical names
/instance5
/instance7
and i dont know which TYPE of object it is.
so i like to access theses instances somehow.
/instance5.getmytype() (getmytype() would be a function)
How many types do you have? If you have a handful or so you could assign them to different collision object groups and check message.group. You could also use a Lua look-up table keyed on instance id with value bring the type. Or you could have the type as a go.property() and access it using go.get()
If you’re going to use script properties, remember that other_id is the ID of the game object, so to get a script’s properties you have to first get the URL of that script component.
-- get the component called "script" on the "other_id" game object.
msg.url(nil, other_id, "script")
so far collision group all “default”.
i tried for this specific case to set the “bullet from the player” and the “enemy” to a new group like “hittable”.
yet once i change from default group to any other name, all the on_message functions never get triggert in my scripts.
i want to access the gameobject. i still dont see how i could do it with the “msg.url() statement”.
or can i get the attribute of the object too?
as
Result=msg.url(nil,other_id, “type_variable”)
You need to have a bi-directional mapping of groups and mask:
the bullet group has a mask for enemy ↔ the enemy group has a mask for bullet
What do you mean when you say this? Do you want to read a go.property() from a script on the game object? Or do you want to know the “type” of the game object? Or something else?
In my game I have laser which deal damage to mobs. Laser has following script:
function on_message(self, message_id, message, sender)
if message_id == hash("collision_response") then
msg.post(message.other_id, "do_damage", {damage = self.damage * self.damage })
end
end
Mob, who takes damage has following script:
function on_message(self, message_id, message, sender)
if message_id == hash("do_damage") then
self.hp = self.hp - message.damage
end
end
ok, now i understand how this collision group feature works! thanks a lot. mask means (groups) that trigger the collision message. with this i can easily distinguish the objects.
i appreciate your help and i guess, the manual could explain this a bit better…
and one question towards your solution:
why do you register the collision on the enemy and then send a msg to the origin/player (with: do_damage)?
why not register the collision at the origin/player and call the function do_damage directly there?
it looks a bit indirect. but i shows very well the concept of message sending.
I may have other collisions for my mob and I want mob to take damage only when it collides with laser. Is there a way to define which exactly collision happens?
Also, I have damage unique data for each of 4 lasers and I store it in laser’s script.
Thanks for all replies, i will summarize 2 solutions quickly.
Working Solution1:
If you have a go.property on the gameobject called “hitpoint” the code to access the property on collision is:
function on_message(self, message_id, message, sender)
local my_url=msg.url(nil, message.other_id, "script")
local value=go.get(my_url, "hitpoint")
print(value)
end
Working Solution2:
Use the CollisionGroups as stated above. Yet its limited to know which GROUP collided with the object.
function on_message(self, message_id, message, sender)
if message.group == hash("pbullet") then
--do sth when collision with pbullet happend
end
end
