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What is the meaning of Vector3.back?

What is the meaning of Vector3.back?

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asked Apr 05, 2012 at 02:46 AM

supermaer gravatar image

supermaer
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3 answers: sort voted first

It is shorthand for writing Vector3(0,0,-1)

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answered Apr 05, 2012 at 07:46 AM

kolban gravatar image

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There is no such command. Try instead -Vector3.forward. ;)

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answered Apr 05, 2012 at 02:51 AM

Kleptomaniac gravatar image

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It's not mentioned in the script reference, but this does compile and run for me in Unity 3.5.0f5:

 Debug.Log(Vector3.back);
 //output is "(0.0, 0.0, -1.0)"

Shame the reference isn't more up to date, really. = It's only as useful as it is authoritative, IMO.

Apr 05, 2012 at 03:09 AM rutter

Wow, thanks for that! Just tested and Vector3.back is indeed the same as -Vector3.forward ... also tested with Vector3.left ... same as -Vector3.right. I would never have known ...

Apr 05, 2012 at 03:19 AM Kleptomaniac

Actually it's deprecated. It was in Unity in the 1.x days. Obviously it's still technically in Unity, but not officially. Best not to use it. (Surprised it still works though.)

Apr 05, 2012 at 03:12 AM Eric5h5
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Vector3.forward gives you a unit vector pointing along the z axis, or (0,0,1).

Vector3.back gives you the opposite, (0,0,-1).

Neither of these are necessarily useful on their own, but they can be very useful in tandem with other code.

Some simple examples:

 //pos points 1,000 units down the z axis
 pos = Vector3.forward * 1000f;

 //bar equals foo with zeroed x and y components
 bar = Vector3.Scale(foo, Vector3.forward);

 //baz points down the z axis with length equal to foo's
 baz = Vector3.forward * foo.magnitude;

Those examples don't necessarily make sense out of context, unfortunately. The more you know about vector math, the more apparent the utility of these values should be.

Remember that vectors express a direction and length. A unit vector, with length one, can be thought of as expressing a pure direction. That's very useful in game development.

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answered Apr 05, 2012 at 03:07 AM

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asked: Apr 05, 2012 at 02:46 AM

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Last Updated: Apr 05, 2012 at 07:46 AM