How do I control the camera position (in between borders)?

Question

Hi guys and gals, I'm making a 2d sidescroller to touch devices and I'm currently stuck with the camera movement.

The camera starts at the given position, but the problem is that when I click on the screen, the camera goes off the scene and far to the right. So I have to drag me back (the camera) to the scene w$$anonymous$$le I hold the mouse button down. When I release the button it stays in position - but when I click again to scroll the same t$$anonymous$$ng happens again (the camera goes far to the right and I have to drag me back to the scene).

To prevent that the camera shall go off the scene, I have a "leftBorder" and a "rightBorder" where the camera not shall pass and only move in between these borders (aka the scene). The problem #2 is that the if statement is somehow ignored.

What am I doing wrong (or not doing at all)?

// erge

 using UnityEngine;
 using System.Collections;
 
 public class CameraMovement : MonoBehaviour {
     
     public bool isMoving = true;
     
     private float camX;
     private float camY = 38.0f;
     private float camZ = -74.0f;
     
     private float camStartPos = -58.7f;
     private float currentCamPos = Camera.main.transform.position.x;
     
     private float leftBorder = -79.0f;
     private float rightBorder = 87.0f;
     
     void Start () {
         Camera.main.transform.position = new Vector3(camStartPos, camY, camZ);
     }
     
     void Update () {
         // TODO: Move camera w$$anonymous$$le currentCamPos is between the borders
         if(currentCamPos >= leftBorder && currentCamPos <= rightBorder){
             if(Input.GetMouseButton(0)){
                 isMoving = true;
                 transform.position = new Vector3(camX = Input.mousePosition.x, camY, camZ);
                 Debug.Log("Mouse X Pos: " + Input.mousePosition.x);
             }
             else{
                 Debug.Log("Mouse Not Pressed");
             }
         }
         else{
             // TODO: Disable camera movement
             isMoving = false;
         }
     }
 }

Answer 1

Best Answer

Answer by gfvfubb · Jun 05, 2013 at 11:49 PM

You can't assign camera position values straight from mouseinput. It's not the same coordinate system. Well I mean you could if you were always going to have the exact same screen sizes (Screen.height / width) and they perfectly mapped to the area you were covering but that would be absurd, what you really want is a transformation matrix. Try t$$anonymous$$s:

 Ray hovray = Camera.main.ScreenPointToRay(Input.mousePosition);
         RaycastHit hov$$anonymous$$t =  new RaycastHit();
         if (Physics.Raycast(hovray,out hov$$anonymous$$t) ) { 
             wp = hov$$anonymous$$t.point;
             wp.y = 0;

With a ground collider t$$anonymous$$s will show where your mouse is intersecting with the terrain. Change the y value to be above the ground to where you want the camera.

Then save the position of the camera between successive updates when you have a mouseup and use that as the offset for the next mousedown. T$$anonymous$$s should solve your problem as I'm doing the exact same t$$anonymous$$ng with a mouseorbit and I had similar 'jumping' issues. If t$$anonymous$$s isn't clear enough say so.

There's another function also you can check out in API docs: ScreenToWorldPoint here is an example; The z coordinate is distance from the camera projection into the world. So t$$anonymous$$s resolves coordinates 30 units in from of the camera where the mouse is projecting through.

 Vector3 temps = Input.mousePosition;
 temps.z = 30;
 glit.transform.position = Camera.main.ScreenToWorldPoint(temps);

Alternatively if you don't want to do t$$anonymous$$s, just save the camera offset and mouse offset from mouseup, and then increase the camera's position by the difference in Input.mousepos values multiplied by a speed constant. Use GetInput for more sensitivity also.

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pborg · Jun 06, 2013 at 01:10 AM 0

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gfvfubb is right. Use ScreenPointToRay & Raycast to get the new position. You may also want to use an invisible plane in the background of the level to give a stop point for the rays. That last one may not be necessary though; correct me if I'm wrong.

erge · Jun 06, 2013 at 08:25 PM 0

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I appreciate your answers! Where do you declare "wp" and what does it mean (is it a Vector3)? Unity doesn't like it. I replaced the code in the Update() with the first code ex. you gave me.

"Then save the position of the camera between successive updates when you have a mouseup and use that as the offset for the next mousedown." Could I use the "currentCamPos" to save the position?

erge · Jul 09, 2013 at 02:40 PM 0

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Thanks, I solved it using the "ScreenToWorldPoint()" as you said.

How do I control the camera position (in between borders)?

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