Camera / Simple Controller from Scratch

I am posting this for a couple of reasons. 1) so that people can learn some basics of how to script. (not only a camera, but other things) and 2) for posterity (I am getting old and tend to forget things.)

So let me begin by telling you what I want; I want an orbital camera that can be used as a third person camera as well.

Getting Started:
We need a plane in the scene, about 20x20, A capsule (default one) the default camera and default light.

We will be creating this in C#, so I created a script called SimpleController, and edited it in. This script will be designed to be put on the capsule, and operate it using WASD for movement.

Code (csharp):

1.  
2. using UnityEngine;
3. using System.Collections;
4.  
5. public class SimpleController : MonoBehaviour
6. {
7.  
8.     // first lets start by defining the camera
9.     Camera camera;
10.  
11.  
12.     // Use this for initialization
13.     void Start () {
14.         // lets find the camera and put it on the variable.
15.         camera = Camera.main;
16.         if (camera == null) camera = Camera.allCameras[0];
17.     }
18. }
19.  

OK, now lets add some stuff to handle the mouse.

Code (csharp):

1.  
2. using UnityEngine;
3. using System.Collections;
4.  
5. // now lets make sure that the capsule has the proper CharacterController
6. // I put this here, so I can reduce the code you have to read later...
7. [RequireComponent(typeof(CharacterController))]
8. public class SimpleController : MonoBehaviour
9. {
10.     Camera camera;
11.  
12.     // lets store the X and Z values from the mouse here
13.     float x, y;
14.  
15.  
16.  
17.     // Use this for initialization
18.     void Start () {
19.         camera = Camera.main;
20.         if (camera == null) camera = Camera.allCameras[0];
21.  
22.         // lets also capture the current angles;
23.         var euler = camera.transform.eulerAngles;
24.         x = euler.x;
25.         y = euler.y;
26.     }
27. }
28.  

OK, now lets make it work. To do this, we add an update method that will be handled every frame.

Code (csharp):

1.  
2.     void Update()
3.     {
4.         // lets now capture the mouse
5.         // remember:
6.         // Mouse X is side to side, this means that Mouse X actually should control the Y axis of the camera
7.         // Mouse Y is up and down, and should control Axis Y. (using a negative value)
8.         // lastly, 20 is the sensitivity to the mouse.
9.         x -= Input.GetAxis("Mouse Y") * 20;
10.         y += Input.GetAxis("Mouse X") * 20;
11.  
12.         // put the camera in the position of the head of the capsule.
13.         // VERY IMPORTANT!!!
14.         camera.transform.position = transform.position + Vector3.up * 0.5f;
15.  
16.         // assign the rotation to the camera.
17.         camera.transform.eulerAngles = new Vector3(x, y, 0);
18.     }
19.  

Now, with all of this together, we can apply the script to the capsule and it will actually look


Next, lets limit the X so that we can't look upside down.

Code (csharp):

1.  
2.     void Update()
3.     {
4.         x -= Input.GetAxis("Mouse Y") * 20;
5.         y += Input.GetAxis("Mouse X") * 20;
6.  
7.         // add the clamp to the X only
8.         x = ClampAngle(x, -60, 60);
9.  
10.  
11.         camera.transform.position = transform.position + Vector3.up * 0.5f;
12.         camera.transform.eulerAngles = new Vector3(x, y, 0);
13.     }
14.  
15.  
16.     // this is a clamping method designed to allow -180 to 180 clamping
17.     float ClampAngle(float angle, float min, float max) {
18.         angle %= 360;
19.         if (angle > 180) angle -= 360;
20.         return Mathf.Clamp(angle, min, max);
21.     }
22.  

now, lets make the capsule look in that direction. Remember that we must always be vertical.

Code (csharp):

1.  
2.     void Update()
3.     {
4.         x -= Input.GetAxis("Mouse Y") * 20;
5.         y += Input.GetAxis("Mouse X") * 20;
6.  
7.         x = ClampAngle(x, -60, 60);
8.         camera.transform.position = transform.position + Vector3.up * 0.5f;
9.         camera.transform.eulerAngles = new Vector3(x, y, 0);
10.  
11.         // get the look at point which is in front of the camera.
12.         var lookAt = camera.transform.TransformPoint(Vector3.forward);
13.         // re-assign the y position to that of the capsule.
14.         lookAt.y = transform.position.y;
15.         // now make the capsule look at the point.
16.         transform.LookAt(lookAt);
17.     }
18.  

OK, now lets look at movement WASD...

Code (csharp):

1.  
2.     void Update()
3.     {
4.         x -= Input.GetAxis("Mouse Y") * 20;
5.         y += Input.GetAxis("Mouse X") * 20;
6.  
7.         x = ClampAngle(x, -60, 60);
8.         camera.transform.position = transform.position + Vector3.up * 0.5f;
9.         camera.transform.eulerAngles = new Vector3(x, y, 0);
10.  
11.         var lookAt = camera.transform.TransformPoint(Vector3.forward);
12.         lookAt.y = transform.position.y;
13.         transform.LookAt(lookAt);
14.  
15.         // lets start simple. Collect the Horizontal and Vertical from the keyboard.
16.         var move = Vector3.zero;
17.         move.z = Input.GetAxis("Vertical");
18.         move.x = Input.GetAxis("Horizontal");
19.         // now transform this into the direction based on the capsule
20.         move = transform.TransformDirection(move);
21.         // get and apply this to the controller using Simple Move.
22.         var controller = GetComponent<CharacterController>();
23.         controller.SimpleMove(move);
24.     }
25.  

OK, now that we have some movement, lets give it some speed...

Code (csharp):

1.  
2.     // lets define speed as a global public variable
3.     public float speed = 8;
4.  
5.     // lets now update the Update to handle this.
6.     void Update()
7.     {
8.         x -= Input.GetAxis("Mouse Y") * 20;
9.         y += Input.GetAxis("Mouse X") * 20;
10.  
11.         x = ClampAngle(x, -60, 60);
12.         camera.transform.position = transform.position + Vector3.up * 0.5f;
13.         camera.transform.eulerAngles = new Vector3(x, y, 0);
14.  
15.         var lookAt = camera.transform.TransformPoint(Vector3.forward);
16.         lookAt.y = transform.position.y;
17.         transform.LookAt(lookAt);
18.  
19.         var move = Vector3.zero;
20.         move.z = Input.GetAxis("Vertical");
21.         move.x = Input.GetAxis("Horizontal");
22.  
23.         // now first, we need to make sure we use something to clamp the movement.
24.         // if we press vertical and horizontal at the same time, the movement is faster than if
25.         // we just pressed either by themselves.
26.         // we need to limit this.
27.         if (move.sqrMagnitude > 1) move.Normalize();
28.  
29.         // now, we make the move speed based on our variable that we added.
30.         move *= speed;
31.  
32.         move = transform.TransformDirection(move);
33.         var controller = GetComponent<CharacterController>();
34.         controller.SimpleMove(move);
35.     }
36.  

OK, now lets look at the third person aspect of this. A third person camera is the exact same camera as a first person camera, its just that we move the camera back so that we see the capsule from a distance.

Lets see how this works.

Code (csharp):

1.  
2.     // these are the minimum and maximum for third person distances.
3.     public float minThirdPersonDistance = 0;
4.     public float maxThirdPersonDistance = 20;
5.     float thirdPersonDistance = 0;
6.  
7.  
8.     void Update()
9.     {
10.         x -= Input.GetAxis("Mouse Y") * 20;
11.         y += Input.GetAxis("Mouse X") * 20;
12.  
13.         x = ClampAngle(x, -60, 60);
14.         camera.transform.position = transform.position + Vector3.up * 0.5f;
15.         camera.transform.eulerAngles = new Vector3(x, y, 0);
16.  
17.         var lookAt = camera.transform.TransformPoint(Vector3.forward);
18.         lookAt.y = transform.position.y;
19.         transform.LookAt(lookAt);
20.  
21.         var move = Vector3.zero;
22.         move.z = Input.GetAxis("Vertical");
23.         move.x = Input.GetAxis("Horizontal");
24.         if (move.sqrMagnitude > 1) move.Normalize();
25.         move *= speed;
26.         move = transform.TransformDirection(move);
27.         var controller = GetComponent<CharacterController>();
28.         controller.SimpleMove(move);
29.  
30.         // specfically, we put this code after the positioning of the camera
31.         // so that we dont affect the position or look rotation of the capsule.
32.         // lets get the mousewheel.
33.         // 20 is the sensitivity of the mouse scroll wheel
34.         thirdPersonDistance -= Input.GetAxis("Mouse ScrollWheel") * 20;
35.         // now, we clamp the distance to the min and max
36.         thirdPersonDistance = Mathf.Clamp(thirdPersonDistance, minThirdPersonDistance, maxThirdPersonDistance);
37.         // now, we move the camera back to where it should be.
38.         camera.transform.Translate(-Vector3.forward * thirdPersonDistance, Space.Self);
39.     }
40.  

OK, so that is the basics. Below is all the code in one shot.

Code (csharp):

1.  
2. using UnityEngine;
3. using System.Collections;
4.  
5. [RequireComponent(typeof(CharacterController))]
6. public class SimpleController : MonoBehaviour
7. {
8.     Camera camera; // the camera....
9.     float x, y; // handles mouse capture
10.     public float speed = 8; // for movement
11.     // for scrolling....
12.     public float minThirdPersonDistance = 0;
13.     public float maxThirdPersonDistance = 20;
14.     float thirdPersonDistance = 0;
15.  
16.  
17.     // Use this for initialization
18.     void Start()
19.     {
20.         // set the camera up
21.         camera = Camera.main;
22.         if (camera == null) camera = Camera.allCameras[0];
23.  
24.         // capture the camera's current euler angle.
25.         var euler = camera.transform.eulerAngles;
26.         x = euler.x;
27.         y = euler.y;
28.     }
29.  
30.     void Update()
31.     {
32.         // capture the mouse for the view
33.         x -= Input.GetAxis("Mouse Y") * 20;
34.         y += Input.GetAxis("Mouse X") * 20;
35.  
36.         // clamp the X angle so that we dont look upside down.
37.         x = ClampAngle(x, -60, 60);
38.         camera.transform.position = transform.position + Vector3.up * 0.5f;
39.         camera.transform.eulerAngles = new Vector3(x, y, 0);
40.  
41.         // keep the camera looking at the mouse based angles
42.         var lookAt = camera.transform.TransformPoint(Vector3.forward);
43.         lookAt.y = transform.position.y;
44.         transform.LookAt(lookAt);
45.  
46.         // handle movement
47.         var move = Vector3.zero;
48.         move.z = Input.GetAxis("Vertical");
49.         move.x = Input.GetAxis("Horizontal");
50.         if (move.sqrMagnitude > 1) move.Normalize();
51.         move *= speed;
52.         move = transform.TransformDirection(move);
53.         var controller = GetComponent<CharacterController>();
54.         controller.SimpleMove(move);
55.  
56.         // handle the third person camera
57.         thirdPersonDistance -= Input.GetAxis("Mouse ScrollWheel") * 20;
58.         thirdPersonDistance = Mathf.Clamp(thirdPersonDistance, minThirdPersonDistance, maxThirdPersonDistance);
59.         camera.transform.Translate(-Vector3.forward * thirdPersonDistance, Space.Self);
60.     }
61.  
62.     // clamp the current angle
63.     float ClampAngle(float angle, float min, float max) {
64.         angle %= 360;
65.         if (angle > 180) angle -= 360;
66.         return Mathf.Clamp(angle, min, max);
67.     }
68. }
69.