当仅在x和z轴上拖放3d对象时，如何使其完全跟随鼠标？

Question

I want to drag and drop an object on only the x and z axis. So far the code does do that, only the object moves slower than the mouse. How do I make it follow the mouse exactly?

As I'm still new to coding, I've tried implementing different codes into my code and tried to edit it from what I've learned, but I can't figure it out.

    Vector3 dist;
    Vector3 startPos;
    float posX;
    float posZ;
    float posY;
    void OnMouseDown()
    {
        startPos = transform.position;
        dist = Camera.main.WorldToScreenPoint(transform.position);
        posX = Input.mousePosition.x - dist.x;
        posY = Input.mousePosition.y - dist.y;
        posZ = Input.mousePosition.z - dist.z;
    }

    void OnMouseDrag()
    {
        float disX = Input.mousePosition.x - posX;
        float disY = Input.mousePosition.y - posY;
        float disZ = Input.mousePosition.z - posZ;
        Vector3 lastPos = Camera.main.ScreenToWorldPoint(new Vector3(disX, disY, disZ));
        transform.position = new Vector3(lastPos.x, 4.8f, lastPos.z);
    }

I expect that the object follows the mouse, but it moves in the same direction as the mouse, only slower.

Answer 1

I would get a starting position in world space by raycasting from the pointer to a plane at the surface level. Then on drag, do the same raycast. Find the difference from the first raycast to the current raycast and add that to the starting position of the object to get the new position of the object:

Vector3 dist;
Vector3 startPos;
Vector3 startIntersect;

bool clickedOnGround = false;

void OnMouseDown()
{
    clickedOnGround = false;
    startPos = transform.position;

    Ray cameraRay = Camera.main.ScreenPointToRay(Input.mousePosition);
    Plane groundPlane = new Plane(Vector3.down, new Vector3(0f, 4.8f, 0f)); 

    float planeHitDist;
    if (groundPlane.Raycast(cameraRay, out planeHitDist))  
    {
        clickedOnGround = true;

        startIntersect = cameraRay.GetPoint(planeHitDist);
    }
}

void OnMouseDrag()
{
    Ray cameraRay = Camera.main.ScreenPointToRay(Input.mousePosition);
    Plane groundPlane = new Plane(Vector3.down, new Vector3(0f, 4.8f, 0f)); 

    float planeHitDist;
    if (groundPlane.Raycast(cameraRay, out planeHitDist))  
    {
        Vector3 newIntersect = cameraRay.GetPoint(planeHitDist);
        transform.position = startPos + (newIntersect - startIntersect);
    }
}