diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9f0176e..c20195b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Changed `MAX_STEER_POINTS` from class constant to local. 
 - Changed `List<DtStraightPath>` to `Span<DtStraightPath>` for enhanced memory efficiency
 - Changed `DtWriter` to a static class and renamed it to `RcIO`
+- Changed class `Trajectory` to interface `ITrajectory`
 
 ### Removed
 - Nothing
diff --git a/src/DotRecast.Detour.Extras/Jumplink/ClimbTrajectory.cs b/src/DotRecast.Detour.Extras/Jumplink/ClimbTrajectory.cs
index a8abd77..978d6ef 100644
--- a/src/DotRecast.Detour.Extras/Jumplink/ClimbTrajectory.cs
+++ b/src/DotRecast.Detour.Extras/Jumplink/ClimbTrajectory.cs
@@ -4,9 +4,9 @@ using DotRecast.Core.Numerics;
 
 namespace DotRecast.Detour.Extras.Jumplink
 {
-    public class ClimbTrajectory : Trajectory
+    public class ClimbTrajectory : ITrajectory
     {
-        public override RcVec3f Apply(RcVec3f start, RcVec3f end, float u)
+        public RcVec3f Apply(RcVec3f start, RcVec3f end, float u)
         {
             return new RcVec3f()
             {
diff --git a/src/DotRecast.Detour.Extras/Jumplink/EdgeExtractor.cs b/src/DotRecast.Detour.Extras/Jumplink/EdgeExtractor.cs
index 7810533..0daa7f6 100644
--- a/src/DotRecast.Detour.Extras/Jumplink/EdgeExtractor.cs
+++ b/src/DotRecast.Detour.Extras/Jumplink/EdgeExtractor.cs
@@ -20,7 +20,7 @@ namespace DotRecast.Detour.Extras.Jumplink
                 {
                     if (i > 41 || i < 41)
                     {
-                        //           continue;
+                        // continue;
                     }
 
                     int nvp = mesh.nvp;
@@ -29,7 +29,7 @@ namespace DotRecast.Detour.Extras.Jumplink
                     {
                         if (j != 1)
                         {
-                            //                    continue;
+                            // continue;
                         }
 
                         if (mesh.polys[p + j] == RC_MESH_NULL_IDX)
diff --git a/src/DotRecast.Detour.Extras/Jumplink/EdgeSampler.cs b/src/DotRecast.Detour.Extras/Jumplink/EdgeSampler.cs
index 9a5a468..044ab83 100644
--- a/src/DotRecast.Detour.Extras/Jumplink/EdgeSampler.cs
+++ b/src/DotRecast.Detour.Extras/Jumplink/EdgeSampler.cs
@@ -7,13 +7,13 @@ namespace DotRecast.Detour.Extras.Jumplink
     {
         public readonly GroundSegment start = new GroundSegment();
         public readonly List<GroundSegment> end = new List<GroundSegment>();
-        public readonly Trajectory trajectory;
+        public readonly ITrajectory trajectory;
 
         public readonly RcVec3f ax = new RcVec3f();
         public readonly RcVec3f ay = new RcVec3f();
         public readonly RcVec3f az = new RcVec3f();
 
-        public EdgeSampler(JumpEdge edge, Trajectory trajectory)
+        public EdgeSampler(JumpEdge edge, ITrajectory trajectory)
         {
             this.trajectory = trajectory;
             ax = RcVec3f.Subtract(edge.sq, edge.sp);
diff --git a/src/DotRecast.Detour.Extras/Jumplink/GroundSample.cs b/src/DotRecast.Detour.Extras/Jumplink/GroundSample.cs
index 41cffc1..3c22759 100644
--- a/src/DotRecast.Detour.Extras/Jumplink/GroundSample.cs
+++ b/src/DotRecast.Detour.Extras/Jumplink/GroundSample.cs
@@ -4,7 +4,7 @@ namespace DotRecast.Detour.Extras.Jumplink
 {
     public class GroundSample
     {
-        public RcVec3f p = new RcVec3f();
+        public RcVec3f p;
         public bool validTrajectory;
         public bool validHeight;
     }
diff --git a/src/DotRecast.Detour.Extras/Jumplink/GroundSegment.cs b/src/DotRecast.Detour.Extras/Jumplink/GroundSegment.cs
index 1268bba..dbc8f1a 100644
--- a/src/DotRecast.Detour.Extras/Jumplink/GroundSegment.cs
+++ b/src/DotRecast.Detour.Extras/Jumplink/GroundSegment.cs
@@ -4,8 +4,8 @@ namespace DotRecast.Detour.Extras.Jumplink
 {
     public class GroundSegment
     {
-        public RcVec3f p = new RcVec3f();
-        public RcVec3f q = new RcVec3f();
+        public RcVec3f p;
+        public RcVec3f q;
         public GroundSample[] gsamples;
         public float height;
     }
diff --git a/src/DotRecast.Detour.Extras/Jumplink/ITrajectory.cs b/src/DotRecast.Detour.Extras/Jumplink/ITrajectory.cs
new file mode 100644
index 0000000..dfd04a5
--- /dev/null
+++ b/src/DotRecast.Detour.Extras/Jumplink/ITrajectory.cs
@@ -0,0 +1,10 @@
+using System;
+using DotRecast.Core.Numerics;
+
+namespace DotRecast.Detour.Extras.Jumplink
+{
+    public interface ITrajectory
+    {
+        public RcVec3f Apply(RcVec3f start, RcVec3f end, float u);
+    }
+}
\ No newline at end of file
diff --git a/src/DotRecast.Detour.Extras/Jumplink/JumpLink.cs b/src/DotRecast.Detour.Extras/Jumplink/JumpLink.cs
index 4f02b83..9482b01 100644
--- a/src/DotRecast.Detour.Extras/Jumplink/JumpLink.cs
+++ b/src/DotRecast.Detour.Extras/Jumplink/JumpLink.cs
@@ -10,6 +10,6 @@ namespace DotRecast.Detour.Extras.Jumplink
         public GroundSample[] endSamples;
         public GroundSegment start;
         public GroundSegment end;
-        public Trajectory trajectory;
+        public ITrajectory trajectory;
     }
 }
\ No newline at end of file
diff --git a/src/DotRecast.Detour.Extras/Jumplink/JumpTrajectory.cs b/src/DotRecast.Detour.Extras/Jumplink/JumpTrajectory.cs
index 080eff3..663b558 100644
--- a/src/DotRecast.Detour.Extras/Jumplink/JumpTrajectory.cs
+++ b/src/DotRecast.Detour.Extras/Jumplink/JumpTrajectory.cs
@@ -4,7 +4,7 @@ using DotRecast.Core.Numerics;
 
 namespace DotRecast.Detour.Extras.Jumplink
 {
-    public class JumpTrajectory : Trajectory
+    public class JumpTrajectory : ITrajectory
     {
         private readonly float jumpHeight;
 
@@ -13,7 +13,7 @@ namespace DotRecast.Detour.Extras.Jumplink
             this.jumpHeight = jumpHeight;
         }
 
-        public override RcVec3f Apply(RcVec3f start, RcVec3f end, float u)
+        public RcVec3f Apply(RcVec3f start, RcVec3f end, float u)
         {
             return new RcVec3f
             {
diff --git a/src/DotRecast.Detour.Extras/Jumplink/Trajectory.cs b/src/DotRecast.Detour.Extras/Jumplink/Trajectory.cs
deleted file mode 100644
index e51802c..0000000
--- a/src/DotRecast.Detour.Extras/Jumplink/Trajectory.cs
+++ /dev/null
@@ -1,13 +0,0 @@
-using System;
-using DotRecast.Core.Numerics;
-
-namespace DotRecast.Detour.Extras.Jumplink
-{
-    public class Trajectory
-    {
-        public virtual RcVec3f Apply(RcVec3f start, RcVec3f end, float u)
-        {
-            throw new NotImplementedException();
-        }
-    }
-}
\ No newline at end of file
diff --git a/src/DotRecast.Detour.Extras/Jumplink/TrajectorySampler.cs b/src/DotRecast.Detour.Extras/Jumplink/TrajectorySampler.cs
index a2ec1f1..7d3dcad 100644
--- a/src/DotRecast.Detour.Extras/Jumplink/TrajectorySampler.cs
+++ b/src/DotRecast.Detour.Extras/Jumplink/TrajectorySampler.cs
@@ -32,7 +32,7 @@ namespace DotRecast.Detour.Extras.Jumplink
             }
         }
 
-        private bool SampleTrajectory(JumpLinkBuilderConfig acfg, RcHeightfield solid, RcVec3f pa, RcVec3f pb, Trajectory tra)
+        private bool SampleTrajectory(JumpLinkBuilderConfig acfg, RcHeightfield solid, RcVec3f pa, RcVec3f pb, ITrajectory tra)
         {
             float cs = Math.Min(acfg.cellSize, acfg.cellHeight);
             float d = RcVecUtils.Dist2D(pa, pb) + MathF.Abs(pa.Y - pb.Y);
diff --git a/src/DotRecast.Recast.Demo/Tools/JumpLinkBuilderSampleTool.cs b/src/DotRecast.Recast.Demo/Tools/JumpLinkBuilderSampleTool.cs
index 4b31c47..db2fc07 100644
--- a/src/DotRecast.Recast.Demo/Tools/JumpLinkBuilderSampleTool.cs
+++ b/src/DotRecast.Recast.Demo/Tools/JumpLinkBuilderSampleTool.cs
@@ -417,7 +417,7 @@ public class JumpLinkBuilderSampleTool : ISampleTool
     }
 
 
-    private void DrawTrajectory(RecastDebugDraw dd, JumpLink link, RcVec3f pa, RcVec3f pb, Trajectory tra, int cola)
+    private void DrawTrajectory(RecastDebugDraw dd, JumpLink link, RcVec3f pa, RcVec3f pb, ITrajectory tra, int cola)
     {
     }