Stash work on refactor of trajecotry

Assets/Scripts/Common/Visual/TrajectoryPreview.cs

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+using Core;
+using UnityEngine;
+
+namespace Common.Visual
+{
+    /// <summary>
+    /// Common trajectory preview component for slingshot-style mechanics.
+    /// Displays a line showing the predicted arc of a launched projectile.
+    /// Supports multiple API overloads for different use cases.
+    /// </summary>
+    [RequireComponent(typeof(LineRenderer))]
+    public class TrajectoryPreview : MonoBehaviour
+    {
+        [Header("Trajectory Settings")]
+        [Tooltip("Number of points in trajectory line")]
+        [SerializeField] private int trajectoryPoints = 50;
+        
+        [Tooltip("Time step between trajectory points (seconds)")]
+        [SerializeField] private float timeStep = 0.1f;
+        
+        [Tooltip("Ground level Y position (trajectory stops here)")]
+        [SerializeField] private float groundLevel = -10f;
+        
+        [Header("Visual")]
+        [Tooltip("Color of trajectory line")]
+        [SerializeField] private Color lineColor = Color.yellow;
+        
+        [Tooltip("Width of trajectory line")]
+        [SerializeField] private float lineWidth = 0.1f;
+        
+        private LineRenderer _lineRenderer;
+        private bool _isLocked;
+        private float _lockTimer;
+        private float _lockDuration;
+        
+        #region Unity Lifecycle
+        
+        private void Awake()
+        {
+            _lineRenderer = GetComponent<LineRenderer>();
+            
+            if (_lineRenderer != null)
+            {
+                _lineRenderer.startWidth = lineWidth;
+                _lineRenderer.endWidth = lineWidth;
+                _lineRenderer.startColor = lineColor;
+                _lineRenderer.endColor = lineColor;
+                _lineRenderer.positionCount = trajectoryPoints;
+                _lineRenderer.enabled = false;
+            }
+        }
+        
+        private void Update()
+        {
+            if (_isLocked)
+            {
+                _lockTimer += Time.deltaTime;
+                if (_lockTimer >= _lockDuration)
+                {
+                    _isLocked = false;
+                    Hide();
+                }
+            }
+        }
+        
+        #endregion
+        
+        #region Public API - Visibility
+        
+        /// <summary>
+        /// Show the trajectory preview line
+        /// </summary>
+        public void Show()
+        {
+            if (_lineRenderer != null)
+            {
+                _lineRenderer.enabled = true;
+            }
+        }
+        
+        /// <summary>
+        /// Hide the trajectory preview line (unless locked)
+        /// </summary>
+        public void Hide()
+        {
+            if (_isLocked) return;
+            
+            if (_lineRenderer != null)
+            {
+                _lineRenderer.enabled = false;
+            }
+        }
+        
+        /// <summary>
+        /// Lock the trajectory display for a duration (keeps showing after launch)
+        /// </summary>
+        public void LockTrajectory(float duration)
+        {
+            _isLocked = true;
+            _lockTimer = 0f;
+            _lockDuration = duration;
+            
+            if (_lineRenderer != null)
+            {
+                _lineRenderer.enabled = true;
+            }
+        }
+        
+        #endregion
+        
+        #region Public API - Update Trajectory (Multiple Overloads)
+        
+        /// <summary>
+        /// Update trajectory from velocity and gravity directly.
+        /// Most explicit - caller calculates everything.
+        /// </summary>
+        public void UpdateTrajectory(Vector2 startPos, Vector2 velocity, float gravity)
+        {
+            if (_lineRenderer == null) return;
+            
+            CalculateAndSetTrajectory(startPos, velocity, gravity);
+        }
+        
+        /// <summary>
+        /// Update trajectory from launch force and mass.
+        /// Calculates velocity as: v = (direction * force) / mass
+        /// </summary>
+        public void UpdateTrajectory(Vector2 startPos, Vector2 direction, float force, float mass, float gravity)
+        {
+            if (_lineRenderer == null) return;
+            
+            if (mass <= 0f)
+            {
+                Logging.Warning("[TrajectoryPreview] Cannot calculate trajectory with zero or negative mass!");
+                return;
+            }
+            
+            Vector2 velocity = (direction * force) / mass;
+            CalculateAndSetTrajectory(startPos, velocity, gravity);
+        }
+        
+        /// <summary>
+        /// Update trajectory from prefab's Rigidbody2D properties.
+        /// Reads mass and gravityScale from prefab, calculates gravity automatically.
+        /// </summary>
+        public void UpdateTrajectory(Vector2 startPos, Vector2 direction, float force, GameObject prefab)
+        {
+            if (_lineRenderer == null || prefab == null) return;
+            
+            var rb = prefab.GetComponent<Rigidbody2D>();
+            if (rb == null)
+            {
+                Logging.Warning($"[TrajectoryPreview] Prefab '{prefab.name}' has no Rigidbody2D!");
+                return;
+            }
+            
+            float mass = rb.mass;
+            float gravity = Physics2D.gravity.magnitude * rb.gravityScale;
+            
+            if (mass <= 0f)
+            {
+                Logging.Warning($"[TrajectoryPreview] Prefab '{prefab.name}' has zero mass!");
+                return;
+            }
+            
+            Vector2 velocity = (direction * force) / mass;
+            CalculateAndSetTrajectory(startPos, velocity, gravity);
+        }
+        
+        #endregion
+        
+        #region Internal Calculation
+        
+        /// <summary>
+        /// Calculate and set trajectory points using kinematic formula.
+        /// Uses: y = y0 + v*t - 0.5*g*t^2
+        /// </summary>
+        private void CalculateAndSetTrajectory(Vector2 startPos, Vector2 velocity, float gravity)
+        {
+            Vector3[] points = new Vector3[trajectoryPoints];
+            
+            for (int i = 0; i < trajectoryPoints; i++)
+            {
+                float time = i * timeStep;
+                
+                // Kinematic equations
+                float x = startPos.x + velocity.x * time;
+                float y = startPos.y + velocity.y * time - 0.5f * gravity * time * time;
+                
+                points[i] = new Vector3(x, y, 0);
+                
+                // Stop at ground level
+                if (y <= groundLevel)
+                {
+                    // Fill remaining points at ground level
+                    for (int j = i; j < trajectoryPoints; j++)
+                    {
+                        float tGround = j * timeStep;
+                        float xGround = startPos.x + velocity.x * tGround;
+                        points[j] = new Vector3(xGround, groundLevel, 0);
+                    }
+                    break;
+                }
+            }
+            
+            _lineRenderer.positionCount = trajectoryPoints;
+            _lineRenderer.SetPositions(points);
+        }
+        
+        #endregion
+        
+        #region Configuration
+        
+        /// <summary>
+        /// Set the number of trajectory points (for performance tuning)
+        /// </summary>
+        public void SetTrajectoryPoints(int points)
+        {
+            trajectoryPoints = Mathf.Max(5, points);
+            if (_lineRenderer != null)
+            {
+                _lineRenderer.positionCount = trajectoryPoints;
+            }
+        }
+        
+        /// <summary>
+        /// Set the time step between points
+        /// </summary>
+        public void SetTimeStep(float step)
+        {
+            timeStep = Mathf.Max(0.01f, step);
+        }
+        
+        #endregion
+    }
+}
+