Ramp wall/ceiling climb movement for precise placement

Ramp the along-surface climb velocity via a gentle acceleration instead of
snapping to full speed, so a brief tap nudges only a little. Sprint scales
the accel so it stays snappy; releasing decelerates at the ground decel rate.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/Scripts/PlayerCharacterController.cs

@@ -8,7 +8,7 @@ using UnityEngine.InputSystem;
 /// and jumping, sliding off too-steep slopes/edges, and a wall-climb mode.
 ///
 /// Wall-climb (entered by pushing the move input into a wall): W/S climb straight up/down the
-/// wall at a constant speed, A/D strafe left/right relative to the camera, and the body always
+/// wall (velocity ramps in via a gentle acceleration for precise placement), A/D strafe left/right relative to the camera, and the body always
 /// faces the wall. Holding the left mouse button and dragging up/down leans the visual mesh out
 /// of or into the wall (only the model + its paint collider move; the capsule stays put, so the
 /// lean can sink into the wall); holding the right mouse button and dragging left/right turns the
@@ -111,6 +111,11 @@ public class PlayerCharacterController : MonoBehaviour
     [Range(0f, 1f)]
     public float wallClimbSpeedMultiplier = 0.5f;
 
+    [Tooltip("How quickly wall/ceiling climb movement ramps up to speed (units/second²). Kept low so brief " +
+             "taps nudge only a little for precise placement; scaled up while sprinting so sprint stays snappy.")]
+    [Min(0.01f)]
+    public float wallClimbAcceleration = 5f;
+
     [Tooltip("Speed multiplier for the mantle (pulling up over the top edge), independent of the climb speed. Multiplies moveSpeed; 1 = full walk speed, >1 = snappier pull-up.")]
     [Min(0f)]
     public float wallMantleSpeedMultiplier = 1.5f;
@@ -229,6 +234,7 @@ public class PlayerCharacterController : MonoBehaviour
     private NetworkPlayerSetup _setup;    // sibling role source; null on non-networked test instances
     private float _verticalVelocity;
     private Vector3 _horizontalVelocity;  // smoothed horizontal move velocity (accel/decel ramp)
+    private Vector3 _climbVelocity;       // smoothed along-surface climb velocity (accel ramp for precise placement)
     private bool _sprinting;              // sprint key state this frame (exposed via IsSprinting)
     private bool _isIdle;                 // snapshot: player essentially still this frame (exposed via IsIdle)
     private bool _movingOnGround;         // snapshot: grounded & moving above the run threshold (exposed via IsMovingOnGround)
@@ -514,6 +520,7 @@ public class PlayerCharacterController : MonoBehaviour
 
         _verticalVelocity = 0f;
         _horizontalVelocity = Vector3.zero;
+        _climbVelocity = Vector3.zero;
         _slideSpeed = 0f;
     }
 
@@ -577,6 +584,7 @@ public class PlayerCharacterController : MonoBehaviour
             _wallStrafeSign = 0;
             _wallClimbSign = 0;
             _climbLeftGround = false;
+            _climbVelocity = Vector3.zero; // start the climb ramp from rest
         }
     }
 
@@ -710,8 +718,8 @@ public class PlayerCharacterController : MonoBehaviour
         }
         else
         {
-            // W/S climb straight up/down the wall at a constant speed (camera pitch never tilts
-            // them). Strafe along the wall's own horizontal tangent, not the live camera-right
+            // W/S climb straight up/down the wall (camera pitch never tilts them; speed ramps in
+            // below). Strafe along the wall's own horizontal tangent, not the live camera-right
             // vector: feeding camera-right in here coupled movement to the orbit camera's
             // per-frame re-aim and jittered sideways motion. The camera only picks the sign.
             Vector3 wallUp = Vector3.ProjectOnPlane(Vector3.up, _wallNormal);
@@ -791,9 +799,18 @@ public class PlayerCharacterController : MonoBehaviour
 
         float climbSpeed = moveSpeed * wallClimbSpeedMultiplier;
         if (sprinting) climbSpeed *= sprintSpeedMultiplier;
-        Vector3 velocity = Vector3.zero;
-        if (alongSurface.sqrMagnitude > 1e-6f)
-            velocity += alongSurface.normalized * climbSpeed;
+        // Ramp the along-surface velocity instead of snapping to full speed: a gentle acceleration
+        // lets a brief tap move you only a little, so you can place yourself precisely (especially
+        // without sprint). Sprint scales the accel too, so it still reaches its higher speed quickly;
+        // releasing decelerates at the ground decel rate for a prompt, controllable stop.
+        Vector3 targetAlong = alongSurface.sqrMagnitude > 1e-6f
+            ? alongSurface.normalized * climbSpeed
+            : Vector3.zero;
+        float climbAccel = targetAlong.sqrMagnitude > 1e-6f
+            ? wallClimbAcceleration * (sprinting ? sprintSpeedMultiplier : 1f)
+            : deceleration;
+        _climbVelocity = Vector3.MoveTowards(_climbVelocity, targetAlong, climbAccel * dt);
+        Vector3 velocity = _climbVelocity;
         if (found)
         {
             // Smoothly hold the capsule one skin-width off the surface (flush): the lean offset no
@@ -1211,6 +1228,7 @@ public class PlayerCharacterController : MonoBehaviour
         _onCeiling = false;
         _lostContactTimer = 0f;
         _verticalVelocity = 0f;
+        _climbVelocity = Vector3.zero;
         // Hand the current lean off to the residual so it eases home (EaseMeshOffsetToRest)
         // instead of snapping; latch the normal since the live one may shift after detaching.
         _meshOffsetResidual = _wallOffset;