Question by perezbalen · Oct 05, 2013 at 03:45 AM · offset local global vectors

Add a Vector3 taking angle into account

I´m trying to move a GameObject a few units in a particular direction. To simplify, say I want a shield 1 unit in front of where the player is facing. I´m doing something like this:

shield.transform.position = player.transform.position + new Vector3(1f,0f,0f);

The problem I have is that the shield is always offset one unit in the x axes, regardless of the rotation of the player (when what I want is for it to be one unit in front of the player).

My guess is that my code adds the vector in global space, but I´ve been unable to make it add the vector in local space.

Thanks for any help.

EDIT: To clarify, the example is not the actual problem. So while doing it another way (like parenting) might fix this particular example, it´s not what I´m looking for (posting the actual problem might be a bit overwhelming, but in short there are a lot of calculations every frame that feed the x,y and z of the Vector3).

I need help in understanding why the adding of the vector is in global space, and how to do it in local space.

Thanks again.

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TrickyHandz · Oct 05, 2013 at 03:50 AM 0

Have you considered making the shield a child of the player transform?

robertbu · Oct 05, 2013 at 04:11 AM 1

@TrickyHandz's idea of making it a child is a great solution, but if you want to position it:

 shield.transform.position = player.transform.position + player.transform.forward * dist;

'dist' is the distance in front of the planer. If it is 1 unit like in your example, then you can leave it off.

weenchehawk · Oct 05, 2013 at 07:09 AM 0

@perezbalen

The problem I have is that the shield is always offset one unit in the x axes, regardless of the rotation of the player (when what I want is for it to be one unit in front of the player).

The reason for this is you are placing it one unit in the x-direction

 shield.transform.position = player.transform.position + new Vector3(1f,0f,0f);

A Vector takes values Vector3(X, Y, Z), and you're adding 1 to the X parameter.

You could fix this using

 shield.transform.position = player.transform.position + new Vector3(0f,0f,1f);

but I much prefer @robertbu's answer of

 shield.transform.position = player.transform.position + player.transform.forward * dist;

whydoidoit · Oct 05, 2013 at 07:31 AM 0

And just to point out that if you want to put something a number of degrees left or right of some vector on the current object, that is also easy:

    shield.transform.position = player.transform.position + Quaternion.AngleAxis(30, player.transform.up) * player.transform.forward;

Put the shield 30 degrees to the right of the player's current forward

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Add a Vector3 taking angle into account

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