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Here is my movement code for the player:

function Go ()
{
horizontal = Input.GetAxis("Horizontal") * speed * Time.deltaTime;
vertical = Input.GetAxis("Vertical") * speed * Time.deltaTime;

if (transform.position.x > 7 || transform.position.x < -7)
{
    if (transform.position.x > 7)
        transform.position.x = 7;
    else
        transform.position.x = -7;

    horizontal = 0;
}
else
    transform.Translate(horizontal,0,0);

if (transform.position.y > 9 || transform.position.y < -1)
    if (transform.position.y > 9)
        transform.position.y = 9;
    else
        transform.position.y = -1;
else
    transform.Translate(0,vertical,0);
}

(WARNING: PSEUDO CODE AHEAD) My problem is when the player attempts to move outside of the boundaries, they do for a split second, THEN the code forces them back. This turns into a player constantly twitching if they constantly try to cross the boundary. What I want, is to grab the player's position from what would happen if they attempted to cross. This is what I mean by what I want:

if(transform.Translate(horizontal,0,0) makes transform.position.x == 7 or -7)
transform.position.x = 7 or -7;
//depending on which side of the screen they're on.

Now I guess that I could make this happen by having a clone box off screen move first, as in:

if(clone.transform.Translate(horizontal,0,0) makes
clone.transform.position.x == 7 or -7)
transform.position.x = 7 or -7;

But I think that would eat up too much resources, and that there is a better solution. Or am I wrong?

Answer 1

0

function Go() {
    horizontal = Input.GetAxis("Horizontal") * speed * Time.deltaTime;
    vertical = Input.GetAxis("Vertical") * speed * Time.deltaTime;

    var pos : Vector3 = transform.position;
    pos.x = Mathf.Clamp(pos.x + horizontal, -7, 7);
    pos.y = Mathf.Clamp(pos.y + vertical, -7, 7);
    transform.position = pos;
}

The link Lipis gave in comment indeed explains the Clamp function. Basically it keeps the value within a certain range so with Mathf.Clamp(value, -7, 7), if value is less than -7, function returns -7, bigger than 7, function returns 7, otherwise it just returns value.

So by making sure we never set the value outside the allowed range we won't get jittering.

answered Mar 15 '10 at 12:44 AM

Jaap Kreijkamp
6.4k ● 20 ● 26 ● 70

Thanks, but could I also have an explanation?

Mar 15 '10 at 12:55 AM The BOOM

@Sethbeastalan check the example here: http://unity3d.com/support/documentation/ScriptReference/Mathf.Clamp.html do you need more?

Mar 15 '10 at 01:18 AM Lipis

I can't vote this up, (yet), but I just wanted to add that the last 4 lines of the script above work amazingly well.

Dec 29 '12 at 12:51 AM samsmithnz

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Player movement boundaries

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