2D car control with mouse position in unity 2D - unity3d

Question

i am new in unity. I want to car game with mouse control to Unity 2D. I was trying this code but not working. Car vibrates when i move mouse over car. I want it to work perfectly when the mouse hovers over the car. how can i do this? my code is as follows:
private void OnMouseOver()
{
// Distance from camera to object. We need this to get the proper calculation.
float camDis = cam.transform.position.y - my.position.y;
// Get the mouse position in world space. Using camDis for the Z axis.
Vector3 mouse = cam.ScreenToWorldPoint (new Vector3 (Input.mousePosition.x, Input.mousePosition.y, camDis));
float AngleRad = Mathf.Atan2 (mouse.y - my.position.y, mouse.x - my.position.x);
float angle = (180 / Mathf.PI) * AngleRad;
body.rotation = angle;
Vector3 temp = Input.mousePosition;
temp.z = 10f; // Set this to be the distance you want the object to be placed in front of the camera.
this.transform.position = Camera.main.ScreenToWorldPoint(temp);
}

Answer 1

I'm not too clear on the effect you want to achieve, but if you just want the object to move and turn gradually instead of instantly changing, that can be achieved using Vector3.MoveTowards and Quaternion.RotateTowards, e.g.:
private void OnMouseOver()
{
// Distance from camera to object. We need this to get the proper calculation.
float camDis = cam.transform.position.y - my.position.y;
// Get the mouse position in world space. Using camDis for the Z axis.
Vector3 mouse = cam.ScreenToWorldPoint (new Vector3 (Input.mousePosition.x, Input.mousePosition.y, camDis));
float AngleRad = Mathf.Atan2 (mouse.y - my.position.y, mouse.x - my.position.x);
float angle = (180 / Mathf.PI) * AngleRad;
//body.rotation = angle; //??
float turnSpeed = 200f;
transform.rotation = Quaternion.RotateTowards(transform.rotation, Quaternion.Euler(0, 0, angle), turnSpeed * Time.deltaTime);
Vector3 temp = Input.mousePosition;
temp.z = 10f; // Set this to be the distance you want the object to be placed in front of the camera.
float moveSpeed = 10f;
transform.position = Vector3.MoveTowards(transform.position, Camera.main.ScreenToWorldPoint(temp), moveSpeed * Time.deltaTime);
}
Edit in response to comment: If you want it to move only when the player begins the drag on the car, then yes, putting it in OnMouseDrag() would work. If you want it to move when the player drags from anywhere on the screen, you'd want to put the movement code in Update() and check whether the left mouse button is being held down using Input.GetMouseButton(0).
If you wanted it to keep moving towards the last mouse position (e.g. player can click on the screen and it will move there while the mouse button is not being held down), you'd need to keep the last mouse location in a class variable and move towards that in Update().
Incidentally if you want it to move a bit more like a car, you could always move it forwards while it turns towards the mouse, rather than moving it directly towards the mouse even if it's facing a different direction.
Here's an example but be aware that I've changed a few things that didn't seem necessary to me, like using my.position rather than transform.position. If you use it you may need to adapt it to suit the rest of your code.
public float maxTurnSpeed = 250f;
public float maxSpeed = 8f;
public float stopDistance = 0.5f;
public float slowDistance = 2.5f;
private void Update()
{
if( !Input.GetMouseButton(0) ) // If the mouse button is NOT being held down this frame
return; // Don't move. (Ideally you would decelerate the car rather than stopping it immediately though.)
// Remove the above two lines and move all of this to OnMouseDrag if you want to require the drag to begin on this object to move it.
// Also note: this code now assumes the object begins in the desired z position and doesn't change it, rather than forcing a z position.
// Distance from camera to object. We need this to get the proper calculation.
float camDis = transform.position.z - Camera.main.transform.position.z; // Changed this to use z instead of y as it appeared to be a mistake(?)
// Get the mouse position in world space. Using camDis for the Z axis.
Vector3 mouse = Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, camDis));
float distanceFromMouse = Vector3.Distance(transform.position, mouse);
// If we're further away from the mouse than stopDistance, move.
if( distanceFromMouse > stopDistance )
{
float speedMultiplier = 1.0f;
float rotationMultiplier = 1.0f;
// If we're closer to the mouse than slowdistance, slow down proportionately to the remaining distance from stopDistance
if( distanceFromMouse < slowDistance )
{
speedMultiplier = (distanceFromMouse - stopDistance) / (slowDistance - stopDistance);
}
// Reduce turning speed as we approach stopDistance, but not by as much as speed is reduced
if( speedMultiplier < 0.5f )
rotationMultiplier = speedMultiplier * 2f;
float AngleRad = Mathf.Atan2(mouse.y - transform.position.y, mouse.x - transform.position.x);
float angle = (180 / Mathf.PI) * AngleRad;
// Turn the car towards facing the mouse position
transform.rotation = Quaternion.RotateTowards(transform.rotation, Quaternion.Euler(0, 0, angle), maxTurnSpeed * rotationMultiplier * Time.deltaTime);
// Move the car towards its transform.right vector.
transform.position += transform.right * (maxSpeed * speedMultiplier * Time.deltaTime);
}
}