Using Plane.Raycast (Unity)

z4gon
z4gon

Optimizing the Raycast to use pure geometry instead of doing Physics Queries to check collisions with colliders.

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References

Table of Content

Optimization

  • This operation is more efficient than the physics based Raycast with colliders.
  • Instead of making Physics Queries, and checking for Colliders in the Scene, this operation is purely geometrical.

Raycast to the Plane

  • Define a Plane using three points.
  • Use Camera.ViewportPointToRay to obtain a ray and raycast it onto the plane.
  • Obtain the point in space using ray.getPoint(distance).
1public Camera mainCamera;
2public Transform bottomLeft;
3public Transform topRight;
4private Plane plane;
5
6void Awake()
7{
8    this.plane = new Plane(transform.position, bottomLeft.position, topRight.position);
9    PositionCorner(new Vector2(0.0f, 0.0f), bottomLeft);
10    PositionCorner(new Vector2(1.0f, 1.0f), topRight);
11}
12
13private void PositionCorner(Vector2 viewportPoint, Transform corner)
14{
15    var distance = 0.0f;
16    var ray = mainCamera.ViewportPointToRay(viewportPoint);
17    if (this.plane.Raycast(ray, out distance))
18    {
19        corner.transform.position = ray.GetPoint(distance);
20    }
21}

Using the Input System

  • Same as before, but using Camera.ScreenPointToRay.
1public Camera mainCamera;
2public Plane plane;
3private bool isMoving = false;
4
5public void OnMoveAction(InputAction.CallbackContext context)
6{
7    isMoving = context.performed;
8}
9
10public void OnPointerPosition(InputAction.CallbackContext context)
11{
12    if (!isMoving) { return; }
13
14    var point = context.ReadValue<Vector2>();
15
16    var distance = 0.0f;
17    var ray = mainCamera.ScreenPointToRay(point);
18    if (this.plane.Raycast(ray, out distance))
19    {
20        transform.position = ray.GetPoint(distance);
21    }
22}

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