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Assets/Mirror/Examples/Billiards/Ball/WhiteBall.cs

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+using System;
+using Mirror;
+using UnityEngine;
+
+namespace Mirror.Examples.Billiards
+{
+    public class WhiteBall : NetworkBehaviour
+    {
+        public LineRenderer dragIndicator;
+        public Rigidbody rigidBody;
+        public float forceMultiplier = 2;
+        public float maxForce = 40;
+
+        // remember start position to reset to after entering a pocket
+        Vector3 startPosition;
+
+        // cast mouse position on screen to world position
+        bool MouseToWorld(out Vector3 position)
+        {
+            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
+            Plane plane = new Plane(Vector3.up, transform.position);
+            if (plane.Raycast(ray, out float distance))
+            {
+                position = ray.GetPoint(distance);
+                return true;
+            }
+            position = default;
+            return false;
+        }
+
+        void Awake()
+        {
+            startPosition = transform.position;
+        }
+
+        [ClientCallback]
+        void OnMouseDown()
+        {
+            // enable drag indicator
+            dragIndicator.SetPosition(0, transform.position);
+            dragIndicator.SetPosition(1, transform.position);
+            dragIndicator.gameObject.SetActive(true);
+        }
+
+        [ClientCallback]
+        void OnMouseDrag()
+        {
+            // cast mouse position to world
+            if (!MouseToWorld(out Vector3 current)) return;
+
+            // drag indicator
+            dragIndicator.SetPosition(0, transform.position);
+            dragIndicator.SetPosition(1, current);
+        }
+
+        // all players can apply force to the white ball.
+        // (this is not cheat safe)
+        [Command(requiresAuthority = false)]
+        void CmdApplyForce(Vector3 force)
+        {
+            // AddForce has different force modes, see this excellent diagram:
+            // https://www.reddit.com/r/Unity3D/comments/psukm1/know_the_difference_between_forcemodes_a_little/
+            // when applying a one-time force to the ball, we need 'Impulse'.
+            rigidBody.AddForce(force, ForceMode.Impulse);
+        }
+
+        [ClientCallback]
+        void OnMouseUp()
+        {
+            // cast mouse position to world
+            if (!MouseToWorld(out Vector3 current)) return;
+
+            // calculate delta from ball to mouse
+            // ball may have moved since we started dragging,
+            // so always use current ball position here.
+            Vector3 from = transform.position;
+
+            // debug drawing: only works if Gizmos are enabled!
+            Debug.DrawLine(from, current, Color.white, 2);
+
+            // calculate pending force delta
+            Vector3 delta = from - current;
+            Vector3 force = delta * forceMultiplier;
+
+            // there should be a maximum allowed force
+            force = Vector3.ClampMagnitude(force, maxForce);
+
+            // apply force to rigidbody.
+            // it will take a round trip to show the effect.
+            // the goal for prediction will be to show it immediately.
+            CmdApplyForce(force);
+
+            // disable drag indicator
+            dragIndicator.gameObject.SetActive(false);
+        }
+
+        // reset position when entering a pocket.
+        // there's only one trigger in the scene (the pocket).
+        [ServerCallback]
+        void OnTriggerEnter(Collider other)
+        {
+            rigidBody.position = startPosition;
+            rigidBody.Sleep(); // reset forces
+            GetComponent<NetworkRigidbodyUnreliable>().RpcTeleport(startPosition);
+        }
+    }
+}