Constrain one Actor to the position of another?

ozboybrian

I need to constrain arms and a gun to one actor.

I also need to set it up so that it rotates accordingly with the directional aim button.
Any help?
.
.
.
-----------------------------------------------------
Join the GameSalad Community and have your game noticed for free.
http://www.facebook.com/ListYourTopiPhoneGame
List your Top iPhone Game on FaceBook!

DrGlickert

1)
http://www.youtube.com/user/GameSaladCookbook#p/u/40/JnlxvMlPG-k

Video Title: Constraining one Actor to a specific point on another Actor in iOS games made with GameSalad.

Goes through how to constrain 'wheels' on an actor. Can easily be made into arms/legs/guns, etc...

2)
Rotation will be slightly more tricky, I'd get the first part taken care of, then play with the rotation settings so that it lines up correctly.

m456arcus

If it's all the same, then I need something similar: constrain a turret at the proper point on a tank hull, and have it move correctly with the hull.
Edit: Didn't see your post till I finished posting.

DrGlickert

This will do that for ya M456arcus. However, be careful of doing it too many times in a scene and/or on too many actors as it can wear on the processor and effect frame rate negatively.

m456arcus

Good point... However, I was thinking of making some enemies stationary, and tank destroyers don't have turrets. I think I'll be fine for now.

ozboybrian

The video seems like it's constraining to the mouse position...

DrGlickert

Basically this is how you do it. It takes math an planning to accomplish this;

Say you have a player that's body is 50x50, You have a constrain attribute on the body actor of PlayerBodyX and PlayerBodyY. This will be in the middle of the body.

Let's do some arms, legs, and a head:
Head Actor; Let's say your head is 10x10. You'll have 2 constrain attributes on the head actor;
constrain attribute self.position.X to game.PlayerBodyX
constrain attribute self.position.Y to game.PlayerBodyY + 30

Where did I get that 30 from??? If you take the middle of the player body and add 25 to get to the top, then add another 5 for the middle of the player's head you'll get 30. This will place the "Head" actor on top of the body actor.

Now, as you'll notice, we have a LOT of constrain attributes already. We know that Constrain Attribute eats a lot of processor juice so try not to use too many of them.

This should get you started.

Good luck!

m456arcus

Thats what I have now, but the tricky part is when the hull rotates, since its a top down game. It will probably require sin and cosin, but from there I don't have a clue.