How To Rotate Camera With Touch In Unity

June eighth 2020     GameDev, Tutorials, Unity3D

[Tutorial] How to rotate the camera around an object in Unity3D

In this Unity3D tutorial you lot will learn a simple fashion to move the photographic camera around an object in the scene while always looking at it. I shared all of the code, and I added a link to where y'all tin can download the full Unity project too.

If you accept tried RotateAround() and it'due south not working for you, y'all take come to the right place.

You can spring to the solution at the end of the post, download the full project, or follow the tutorial in video format.

Table of contents

1. Detecting the drag
2. Calculating the rotation
3. Moving the camera
4. The solution
5. Extra credit: Modify the rotation speed

We desire to program the camera so that it rotates around an object in the scene, while looking at it, responding to actor input.

As you lot can meet, the photographic camera is doing the yaw and pitch rotations.

(Note: The method explained in this post tin can exist applied to movement acquired by any script too, information technology'southward not restricted to user input.)

Nosotros want that a drag from 1 side of the screen to the other rotates usa 180º around the object. How do we do that?

The screen (the viewport rather) has a size of 1x1 in viewport coordinates.

Since a drag from left to right of the screen volition accept a distance of 1, we take just divers our relation:

one unit in viewport coordinates < == > 180 degrees of camera rotation

Step 1: Observe the drag (= user input)

For this, I created an empty GameObject in the scene (I named information technology "InputController"), and added a script to it (that I created, and named "CameraMovement"). These are the steps:

1. Go to the Unity Editor.
2. In the Scene hierarcy, correct click.
3. Create > Game Object > Emtpy. I named information technology "InputController".
4. In the InputController'due south Inspector, click "Add Script".
5. Type "CameraMovement", hit enter. This created a "CameraMovement.cs" file in your Assets folder, which contains an empty CameraMovement class that extends MonoBehaviour.

(This is the almost basic setup working with an empty project. Of grade y'all can arrange your files and classes however yous prefer.)

Open up CameraMovement.cs with your editor, time to lawmaking!

public class CameraMovement : MonoBehaviour {     void Update()     {         if (Input.GetMouseButtonDown(0))         {             // Will be truthful only in the 1st frame in which it detects the mouse is down (or a tap is happening)         }         else if (Input.GetMouseButton(0))         {             // Will be true as long as the mouse is down or a touch is happening.         }     } }

In Unity games, it is mutual practice to use the Update part to observe player input. (Information technology is besides adept practice not to handle it in the Update function direct, but this is the smallest of projects and we're not going to over-engineer information technology.)

We are using the functions Input.GetMouseButtonDown(0) and Input.GetMouseButton(0) to detect whether the user clicked/tapped or dragged the pointer over the screen.

The Input class too has a convenient mousePosition field which gives the states the position of the arrow (mouse or finger) in screen coordinates. Nosotros'll use information technology in the next stride.

Now that we take the problem defined and the drag detected, nosotros tin can move the camera.

Footstep two: Calculate the rotation

Every frame we volition calculate how much the cursor/finger moved since last frame, and translate it into how many degrees the camera should rotate co-ordinate to our previously divers relation:

1 unit in viewport coordinates < == > 180 degrees of camera rotation

In lodge to do that, we need to store the previous position in a individual field (previousPosition).

This is how the code looks:

public class CameraMovement : MonoBehaviour {     private Vector3 previousPosition          void Update()     {         if (Input.GetMouseButtonDown(0))         {             previousPosition = cam.ScreenToViewportPoint(Input.mousePosition);         }         else if (Input.GetMouseButton(0))         {             Vector3 currentPosition = cam.ScreenToViewportPoint(Input.mousePosition);             Vector3 direction = previousPosition - currentPosition;                          float rotationAroundYAxis = -direction.10 * 180; // photographic camera moves horizontally             bladder rotationAroundXAxis = direction.y * 180; // camera moves vertically                          previousPosition = currentPosition;         }     } }

On the first frame in which the mouse is downward (or the finger touches the screen), we store that position as our previousPosition.

In each subsequent frames, we calculate direction, which is the deviation betwixt the electric current mousePosition and previousPosition.

rotationAroundYAxis and rotationAroundXAxis are the rotations we must add together to the electric current rotation each frame. They are calculated using this very advanced mathematical formula:

(1 / 180º) = (direction / rotationAroundAxis)

In UnityEngine, the forward vector is by convention (0, 0, 1). This is why we are working with the supposition that the camera starts looking "forward", and volition rotate effectually the X and Y axes.

At the terminate of the office, don't forget to shop our currentPosition as our previousPosition!

Okay, only how exercise nosotros ACTUALLY Move THE Photographic camera?

Stride 3: Move the camera

UnityEngine's transform class has a convenient function RotateAround(Vector3 point, Vector3 axis, float angleInDegrees). Here you would use it similar this:

cam.transform.RotateAround(target.transform.position, new Vector3(1, 0, 0), rotationAroundXAxis); cam.transform.RotateAround(target.transform.position, new Vector3(0, 1, 0), rotationAroundYAxis);

As you lot can come across, information technology works, only information technology probably doesn't yield the result yous want:

RotateAround() produces a weird motion that we can't control, atrocious UX, 0 stars, thumbs down. (This is due to the fact that when we rotate around 1 centrality we are moving the other, and viceversa. RotateAround() works well when y'all only allow rotation around 1 centrality.)

Only don't worry! There'southward a manner!

We will use Rotate(Vector3 axis, bladder angleInDegrees, Space relativeTo) instead.

Solution

public class CameraMovement : MonoBehaviour {     [SerializeField] private Camera cam;     [SerializeField] private Transform target;     [SerializeField] private bladder distanceToTarget = 10;          private Vector3 previousPosition;          void Update()     {         if (Input.GetMouseButtonDown(0))         {             previousPosition = cam.ScreenToViewportPoint(Input.mousePosition);         }         else if (Input.GetMouseButton(0))         {             Vector3 newPosition = cam.ScreenToViewportPoint(Input.mousePosition);             Vector3 direction = previousPosition - newPosition;                          float rotationAroundYAxis = -management.x * 180; // photographic camera moves horizontally             float rotationAroundXAxis = direction.y * 180; // camera moves vertically                          cam.transform.position = target.position;                          cam.transform.Rotate(new Vector3(one, 0, 0), rotationAroundXAxis);             cam.transform.Rotate(new Vector3(0, 1, 0), rotationAroundYAxis, Space.World); // <— This is what makes it piece of work!                          cam.transform.Translate(new Vector3(0, 0, -distanceToTarget));                          previousPosition = newPosition;         }     } }

Caption

We created the following private serialized fields, that you must assign in the Unity Editor (only drag the objects into their corresponding box):

• cam references the camera that you want to motion.
• target is the transform component of the gameObject around which nosotros desire to rotate.
• distanceToTarget is the distance from the target that we want the photographic camera to be.

What makes this method work is the fact that we are rotating around the world's Y centrality.

By default, Rotate() and RotateAround() utilize the GameObject'southward local axes (in our case, the camera's). Since rotating around 1 axis messes upwards the other, we need to rotate effectually the world's centrality instead of ours.

Rotate() just rotates the object in its identify. When you rotate effectually something, you lot are besides translating. That'south why nosotros must call cam.transform.Translate(). The guild in which you practice it matters:

• If yous Rotate() first and Interpret() second, yous are rotating your axes, and then moving "according" to them.
• If you lot Translate() first and Rotate() second, you lot are moving "according" to the world'south axes, and and so rotating around yourself in your new position.

So what nosotros need to do for this application is:

Each frame, we set the camera'southward position as the target's position. And so we apply the rotations. Finally, we translate the camera back distanceToTarget units in -Z.

Nosotros defined the rotation speed by the relation:

1 unit in viewport coordinates < == > 180 degrees of camera rotation

While it is ane that works very well, and is very intuitive from a UX perspective, yous could make the statement that 180 is a hadcoded arbitrary number.

Therefore, we can plough the relationship into a private serialized field, so nosotros can edit it in the inspector:

[SerializeField] [Range(0, 360)] private int maxRotationInOneSwipe = 180;

And the code for computing the camera rotation will await similar this:

float rotationAroundYAxis = -direction.x * maxRotationInOneSwipe; // camera moves horizontally bladder rotationAroundXAxis = direction.y * maxRotationInOneSwipe; // camera moves vertically

Source: https://emmaprats.com/p/how-to-rotate-the-camera-around-an-object-in-unity3d/

Posted by: russotookents.blogspot.com

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