feat: Rework CharacterController based on Bepu's

sources/engine/Stride.BepuPhysics/Stride.BepuPhysics/BepuSimulation.cs

@@ -25,6 +25,7 @@
 using BRigidPose = BepuPhysics.RigidPose;
 using SRigidPose = Stride.BepuPhysics.Definitions.RigidPose;
 using SBodyVelocity = Stride.BepuPhysics.Definitions.BodyVelocity;
+using Stride.BepuPhysics.Systems.Characters;
 
 namespace Stride.BepuPhysics;
 
@@ -48,6 +49,8 @@ public sealed class BepuSimulation : IDisposable
     private AwaitRunner _preTickRunner = new();
     private AwaitRunner _postTickRunner = new();
 
+    internal CharacterControllers Characters { get; }
+
     internal BufferPool BufferPool { get; }
 
     internal CollidableProperty<MaterialProperties> CollidableMaterials { get; } = new();
@@ -295,19 +298,21 @@ public BepuSimulation()
 
         var strideNarrowPhaseCallbacks = new StrideNarrowPhaseCallbacks(this, ContactEvents, CollidableMaterials);
         var stridePoseIntegratorCallbacks = new StridePoseIntegratorCallbacks(CollidableMaterials);
-        var solveDescription = new SolveDescription(1, 1);
+        var solveDescription = new SolveDescription(8, 1);
 
         Simulation = Simulation.Create(BufferPool, strideNarrowPhaseCallbacks, stridePoseIntegratorCallbacks, solveDescription);
-        Simulation.Solver.VelocityIterationCount = 8;
-        Simulation.Solver.SubstepCount = 1;
 
         CollidableMaterials.Initialize(Simulation);
         ContactEvents.Initialize();
+
+        Characters = new CharacterControllers(BufferPool);
+        Characters.Initialize(Simulation);
         //CollisionBatcher = new CollisionBatcher<BatcherCallbacks>(BufferPool, Simulation.Shapes, Simulation.NarrowPhase.CollisionTaskRegistry, 0, DefaultBatcherCallbacks);
     }
 
     public void Dispose()
     {
+        Characters.Dispose();
         _threadDispatcher.Dispose();
         BufferPool.Clear();
     }

sources/engine/Stride.BepuPhysics/Stride.BepuPhysics/BodyComponent.cs

@@ -382,17 +382,57 @@ public void ApplyLinearImpulse(Vector3 impulse)
     /// This method sets this body's <see cref="LinearVelocity"/> and <see cref="AngularVelocity"/>, setting these properties after the call would overwrite the result of this method
     /// </remarks>
     public void SetTargetPose(Vector3 targetPosition, Quaternion targetOrientation)
+    {
+        SetTargetPose(targetPosition);
+        SetTargetPose(targetOrientation);
+    }
+
+    /// <summary>
+    /// Set the position this body should try to match on the next physics tick, this will collide with objects on the way
+    /// </summary>
+    /// <remarks>
+    /// Using this function to move objects around is not recommended as it results in unrealistic forces being applied on this body, or unexpected stuttering depending on the input.
+    /// Consider using a constraint between this body and whatever it is following, or using the different Impulse methods instead <br/><br/>
+    /// <paramref name="targetPosition"/> is slightly offset from this entity's Transform <see cref="TransformComponent.Position"/> based on its <see cref="CollidableComponent.CenterOfMass"/> <br/><br/>
+    /// This method sets this body's <see cref="LinearVelocity"/>, setting these properties after the call would overwrite the result of this method
+    /// </remarks>
+    public void SetTargetPose(Vector3 targetPosition)
     {
         if (Simulation is null)
             return;
 
-        Awake = true;
+        float deltaTime = (float)Simulation.FixedTimeStep.TotalSeconds;
+
+        var newVelocity = (targetPosition - Position) / deltaTime;
+        if (newVelocity.LengthSquared() > float.Epsilon)
+        {
+            Awake = true;
+            LinearVelocity = newVelocity;
+        }
+    }
+
+    /// <summary>
+    /// Set the orientation this body should try to match on the next physics tick, this will collide with objects on the way
+    /// </summary>
+    /// <remarks>
+    /// Using this function to move objects around is not recommended as it results in unrealistic forces being applied on this body, or unexpected stuttering depending on the input.
+    /// Consider using a constraint between this body and whatever it is following, or using the different Impulse methods instead <br/><br/>
+    /// This method sets this body's <see cref="AngularVelocity"/>, setting these properties after the call would overwrite the result of this method
+    /// </remarks>
+    public void SetTargetPose(Quaternion targetOrientation)
+    {
+        if (Simulation is null)
+            return;
 
         float deltaTime = (float)Simulation.FixedTimeStep.TotalSeconds;
 
-        LinearVelocity = (targetPosition - Position) / deltaTime;
         var quatDelta = Quaternion.Invert(Orientation) * targetOrientation;
-        AngularVelocity = new Vector3(quatDelta.X, quatDelta.Y, quatDelta.Z) / deltaTime;
+        var newVelocity = new Vector3(quatDelta.X, quatDelta.Y, quatDelta.Z) / deltaTime;
+        if (newVelocity.LengthSquared() > float.Epsilon)
+        {
+            Awake = true;
+            AngularVelocity = newVelocity;
+        }
     }
 
     /// <summary>