Clamp a player to the edge of screen when the resolution changes

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Hi

I am new to using Unity (although my confidence is growing) and I am new to C#. For this project I am working on we are making a side scrolling shooter. Last night i managed to set up my GUI pause menu so it positions itself correctly when the screen resolution changes.

I want to achieve the same thing with my clamping. At the moment I have clamped the player on screen using Mathf.Clamp using this code...

 private int minXValue = -8;
 
 private int maxXValue = 8;
 
 private int minYValue = -3;
 
 private int maxYValue = 5;

     Vector3 pos = transform.position;
     
     pos.y = Mathf.Clamp (pos.y, minYValue, maxYValue);
     
     pos.x = Mathf.Clamp (pos.x, minXValue, maxXValue);
     
     transform.position = pos;

However when the resolution changes naturally the positions I have stated no longer apply (well the Y value works fine). I would like some help to clamp the player to the edge of the screen when the screen resolution changes. Thanks for reading :)

EDIT - Forgot to mention that the clamping code is inside update.

Answer 1

Best Answer

Answer by robertbu · Oct 01, 2013 at 10:53 PM

Your min/max values should be floats, not ints.

A way to find the corners of the screen is to use Camera.ViewportToWorldPoint(); In order to make this work, you need to know the distance from the camera to the players. Then you can do something like:

 void Start() {
    Vector3 lowerLeftCorner = Camera.main.ViewportToWorldPoint(Vector3.zero, dist);
    Vector3 upperRightCorner = Camera.main.ViewportToWorldPoint(new Vector3(1.0, 1,0,dist));
     minXValue = lowerLefCorner.x;
     maxXValue = upperRightCorner.x;
 }

Another solution is to use the ratio of screen width to height. Something like:

 void Start() {
   float halfHeight = (maxYValue - minYValue) / 2.0;
   maxXValue = halfHeight * Screen.width/Screen.height;
   minxXalue = -maxXValue;
 }

Note this second solution assumes the camera is centered left/right on the X axis (as indicated by your -8/8).

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Kebabs · Oct 02, 2013 at 02:52 PM 0

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Thank you for your reply and information. I am still finding it hard to understand this. I tried the first solution. What is dist meant to be? Is it meant to be the new vector 3 position?

And for the second solution I get an error which informs me that $$anonymous$$XValue cannot be used in this context.

Any more help :). Thanks.

Kebabs · Oct 02, 2013 at 03:58 PM 0

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I have now actually got the clamping to work on different resolutions. THAN$$anonymous$$S!! However what happens now is that the player gets pushed slightly off screen but I want the players mesh in its entirety to stay on screen, any ideas dude??

robertbu · Oct 02, 2013 at 04:29 PM 0

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First 'dist'. As mentioned in the writeup, 'dist' is the distance form the camera to the players. Your original code clamped the horizontal distance to -8 and 8. This would only work at a certain distance. $$anonymous$$ove the character closer to the camera, and it would go out of the camera view when at 8/-8. $$anonymous$$ove it away from the camera, and there will be extra space (assu$$anonymous$$g a perspective camera). With the default setup with the camera setting at -10 on the z axis and pointing to positive 'z', if your action occurred at Z=0, 'dist' would be 10.

As for your issue of keeping the character fully visible, I don't know why, but I have some ideas. Probably best to have you post your code and let me take a look.

Kebabs · Oct 02, 2013 at 04:43 PM 0

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Thanks for clearing that up :)

As mentioned in my edited question I have now clamped the player and I am now working on keeping them on screen fully. At the moment the player can go to this point...

alt text

But I want them to stop at this point

alt text

As requested here is my code. Just to note - the private bool playerControlEnabled is just they so I could stop the player at the exact width I wanted.

First how I am moving the player...

 if (playerControlEnabled)
     {
     shield.Translate(Vector3.right * shieldSpeed * Input.GetAxis ("Horizontal") * Time.deltaTime);
     
     
     shield.Translate(Vector3.down * shieldSpeed * Input.GetAxis ("Vertical") * Time.deltaTime);
     }

Normally this is not in an if statement. And this is how they are clamped...

     Vector3 pos = Camera.main.WorldToViewportPoint(transform.position);
     
     pos.x = $$anonymous$$athf.Clamp01(pos.x);
     
     pos.y = $$anonymous$$athf.Clamp01 (pos.y);
     
     transform.position = Camera.main.ViewportToWorldPoint(pos);
     
     if (pos.x <=0.1)
     {
         playerControlEnabled = false;
     }

I was thinking of using the x position in an if statement to stop the player. What would be ideal is if I was able to prevent the player moving left when they hit 0.1 on the x axis but was still able to move in all other directions.

untitled-1.png (7.5 kB)

untitled-2.png (5.7 kB)

Clamp a player to the edge of screen when the resolution changes

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