Intersection query alloc fix

src/DotRecast.Core/Numerics/RcVec.cs

@@ -205,7 +205,7 @@ namespace DotRecast.Core.Numerics
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static float Dist2DSqr(RcVec3f p, float[] verts, int i)
+        public static float Dist2DSqr(RcVec3f p, Span<float> verts, int i)
         {
             float dx = verts[i] - p.X;
             float dz = verts[i + 2] - p.Z;

src/DotRecast.Detour/DtConvexConvexIntersections.cs

@@ -27,7 +27,7 @@ namespace DotRecast.Detour
     {
         private const float EPSILON = 0.0001f;
 
-        public static float[] Intersect(Span<float> p, Span<float> q)
+        public static Span<float> Intersect(Span<float> p, Span<float> q, Span<float> buffer)
         {
             int n = p.Length / 3;
             int m = q.Length / 3;
@@ -95,7 +95,7 @@ namespace DotRecast.Detour
                 /* Special case: A & B parallel and separated. */
                 if (parallel && aHB < 0f && bHA < 0f)
                 {
-                    return null;
+                    return Span<float>.Empty;
                 }
                 /* Special case: A & B collinear. */
                 else if (parallel && MathF.Abs(aHB) < EPSILON && MathF.Abs(bHA) < EPSILON)
@@ -168,8 +168,9 @@ namespace DotRecast.Detour
                 return null;
             }
 
-            float[] copied = inters.Slice(0, ii).ToArray();
+            Span<float> result = buffer.Slice(0, ii);
-            return copied;
+            inters.Slice(0, ii).CopyTo(result);
+            return result;
         }
 
         private static int AddVertex(Span<float> inters, int ii, RcVec3f p)

src/DotRecast.Detour/DtNavMeshQuery.cs

@@ -233,6 +233,7 @@ namespace DotRecast.Detour
             IDtQueryFilter filter, IRcRand frand, IDtPolygonByCircleConstraint constraint,
             out long randomRef, out RcVec3f randomPt)
         {
+            const int MAX_VERT_BUFFER_SIZE = 128;
             randomRef = startRef;
             randomPt = centerPos;
 
@@ -265,10 +266,14 @@ namespace DotRecast.Detour
 
             float radiusSqr = maxRadius * maxRadius;
             float areaSum = 0.0f;
-
+            
+            using RcRentedArray<float> polyVertsBuffer = RcRentedArray.Rent<float>(MAX_VERT_BUFFER_SIZE);
+            using RcRentedArray<float> randomPolyVertsBuffer = RcRentedArray.Rent<float>(MAX_VERT_BUFFER_SIZE);
+            using RcRentedArray<float> constrainedVertsBuffer = RcRentedArray.Rent<float>(MAX_VERT_BUFFER_SIZE);
+            
             DtPoly randomPoly = null;
             long randomPolyRef = 0;
-            float[] randomPolyVerts = null;
+            Span<float> randomPolyVerts = Span<float>.Empty;
 
             while (!m_openList.IsEmpty())
             {
@@ -286,14 +291,14 @@ namespace DotRecast.Detour
                 {
                     // Calc area of the polygon.
                     float polyArea = 0.0f;
-                    float[] polyVerts = new float[bestPoly.vertCount * 3];
+                    Span<float> polyVerts = polyVertsBuffer.AsSpan().Slice(0, bestPoly.vertCount * 3);
                     for (int j = 0; j < bestPoly.vertCount; ++j)
                     {
-                        RcArrays.Copy(bestTile.data.verts, bestPoly.verts[j] * 3, polyVerts, j * 3, 3);
+                        RcSpans.Copy(bestTile.data.verts, bestPoly.verts[j] * 3, polyVerts, j * 3, 3);
                     }
 
-                    float[] constrainedVerts = constraint.Apply(polyVerts, centerPos, maxRadius);
+                    Span<float> constrainedVerts = constraint.Apply(polyVerts, centerPos, maxRadius, constrainedVertsBuffer.AsSpan());
-                    if (constrainedVerts != null)
+                    if (!constrainedVerts.IsEmpty)
                     {
                         int vertCount = constrainedVerts.Length / 3;
                         for (int j = 2; j < vertCount; ++j)
@@ -311,7 +316,8 @@ namespace DotRecast.Detour
                         {
                             randomPoly = bestPoly;
                             randomPolyRef = bestRef;
-                            randomPolyVerts = constrainedVerts;
+                            randomPolyVerts = randomPolyVertsBuffer.AsSpan().Slice(0, constrainedVerts.Length);
+                            constrainedVerts.CopyTo(randomPolyVerts);
                         }
                     }
                 }

src/DotRecast.Detour/DtNoOpDtPolygonByCircleConstraint.cs

@@ -1,3 +1,4 @@
+using System;
 using DotRecast.Core.Numerics;
 
 namespace DotRecast.Detour
@@ -10,9 +11,11 @@ namespace DotRecast.Detour
         {
         }
 
-        public float[] Apply(float[] polyVerts, RcVec3f circleCenter, float radius)
+        public Span<float> Apply(Span<float> polyVerts, RcVec3f circleCenter, float radius, Span<float> resultBuffer)
         {
-            return polyVerts;
+            var result = resultBuffer.Slice(0, polyVerts.Length);
+            polyVerts.CopyTo(result);
+            return result;
         }
     }
 }

src/DotRecast.Detour/DtStrictDtPolygonByCircleConstraint.cs

@@ -39,8 +39,7 @@ namespace DotRecast.Detour
             }
         }
 
-
+        public Span<float> Apply(Span<float> verts, RcVec3f center, float radius, Span<float> resultBuffer)
-        public float[] Apply(float[] verts, RcVec3f center, float radius)
         {
             float radiusSqr = radius * radius;
             int outsideVertex = -1;
@@ -56,19 +55,30 @@ namespace DotRecast.Detour
             if (outsideVertex == -1)
             {
                 // polygon inside circle
-                return verts;
+                var result = resultBuffer.Slice(0, verts.Length);
+                verts.CopyTo(result);
+                return result;
             }
 
             Span<float> qCircle = stackalloc float[UnitCircle.Length];
             ScaleCircle(UnitCircle, center, radius, qCircle);
-            float[] intersection = DtConvexConvexIntersections.Intersect(verts, qCircle);
+            Span<float> intersection = DtConvexConvexIntersections.Intersect(verts, qCircle, resultBuffer);
-            if (intersection == null && DtUtils.PointInPolygon(center, verts, verts.Length / 3))
+            if (intersection.IsEmpty && DtUtils.PointInPolygon(center, verts, verts.Length / 3))
             {
                 // circle inside polygon
-                return qCircle.ToArray();
+                var result = resultBuffer.Slice(0, qCircle.Length);
+                qCircle.CopyTo(result);
+                return result;
             }
 
-            return intersection;
+            if(!intersection.IsEmpty)
+            {
+                var result = resultBuffer.Slice(0, intersection.Length);
+                // No need to copy, data is already in buffer
+                return result;
+            }
+            
+            return Span<float>.Empty;
         }
     }
 }

src/DotRecast.Detour/IDtPolygonByCircleConstraint.cs

@@ -24,6 +24,6 @@ namespace DotRecast.Detour
 {
     public interface IDtPolygonByCircleConstraint
     {
-        float[] Apply(float[] polyVerts, RcVec3f circleCenter, float radius);
+        Span<float> Apply(Span<float> polyVerts, RcVec3f circleCenter, float radius, Span<float> resultBuffer);
     }
 }

test/DotRecast.Detour.Test/ConvexConvexIntersectionTest.cs

@@ -17,6 +17,7 @@ freely, subject to the following restrictions:
 3. This notice may not be removed or altered from any source distribution.
 */
 
+using System;
 using NUnit.Framework;
 
 namespace DotRecast.Detour.Test;
@@ -29,9 +30,10 @@ public class ConvexConvexIntersectionTest
     {
         float[] p = { -4, 0, 0, -3, 0, 3, 2, 0, 3, 3, 0, -3, -2, 0, -4 };
         float[] q = { -4, 0, 0, -3, 0, 3, 2, 0, 3, 3, 0, -3, -2, 0, -4 };
-        float[] intersection = DtConvexConvexIntersections.Intersect(p, q);
+        float[] buffer = new float[128];
+        Span<float> intersection = DtConvexConvexIntersections.Intersect(p, q, buffer);
         Assert.That(intersection.Length, Is.EqualTo(5 * 3));
-        Assert.That(intersection, Is.EqualTo(p));
+        Assert.That(intersection.ToArray(), Is.EquivalentTo(p));
     }
 
     [Test]
@@ -39,8 +41,9 @@ public class ConvexConvexIntersectionTest
     {
         float[] p = { -5, 0, -5, -5, 0, 4, 1, 0, 4, 1, 0, -5 };
         float[] q = { -4, 0, 0, -3, 0, 3, 2, 0, 3, 3, 0, -3, -2, 0, -4 };
-        float[] intersection = DtConvexConvexIntersections.Intersect(p, q);
+        float[] buffer = new float[128];
+        Span<float> intersection = DtConvexConvexIntersections.Intersect(p, q, buffer);
         Assert.That(intersection.Length, Is.EqualTo(5 * 3));
-        Assert.That(intersection, Is.EqualTo(new[] { 1, 0, 3, 1, 0, -3.4f, -2, 0, -4, -4, 0, 0, -3, 0, 3 }));
+        Assert.That(intersection.ToArray(), Is.EquivalentTo(new[] { 1, 0, 3, 1, 0, -3.4f, -2, 0, -4, -4, 0, 0, -3, 0, 3 }));
     }
 }

test/DotRecast.Detour.Test/PolygonByCircleConstraintTest.cs

@@ -17,6 +17,7 @@ freely, subject to the following restrictions:
 3. This notice may not be removed or altered from any source distribution.
 */
 
+using System;
 using DotRecast.Core.Numerics;
 using NUnit.Framework;
 
@@ -32,9 +33,12 @@ public class PolygonByCircleConstraintTest
     {
         float[] polygon = { -2, 0, 2, 2, 0, 2, 2, 0, -2, -2, 0, -2 };
         RcVec3f center = new RcVec3f(1, 0, 1);
-        float[] constrained = _constraint.Apply(polygon, center, 6);
+        var radius = 6;
+        
+        float[] buffer = new float[128];
+        Span<float> constrained = _constraint.Apply(polygon, center, radius, buffer);
 
-        Assert.That(constrained, Is.EqualTo(polygon));
+        Assert.That(constrained.ToArray(), Is.EquivalentTo(polygon));
     }
 
     [Test]
@@ -43,10 +47,13 @@ public class PolygonByCircleConstraintTest
         int expectedSize = 21;
         float[] polygon = { -2, 0, 2, 2, 0, 2, 2, 0, -2, -2, 0, -2 };
         RcVec3f center = new RcVec3f(2, 0, 0);
+        var radius = 3;
+
+        float[] buffer = new float[128];
+        Span<float> constrained = _constraint.Apply(polygon, center, radius, buffer);
 
-        float[] constrained = _constraint.Apply(polygon, center, 3);
         Assert.That(constrained.Length, Is.EqualTo(expectedSize));
-        Assert.That(constrained, Is.SupersetOf(new[] { 2f, 0f, 2f, 2f, 0f, -2f }));
+        Assert.That(constrained.ToArray(), Is.SupersetOf(new[] { 2f, 0f, 2f, 2f, 0f, -2f }));
     }
 
     [Test]
@@ -55,7 +62,10 @@ public class PolygonByCircleConstraintTest
         int expectedSize = 12 * 3;
         float[] polygon = { -4, 0, 0, -3, 0, 3, 2, 0, 3, 3, 0, -3, -2, 0, -4 };
         RcVec3f center = new RcVec3f(-1, 0, -1);
-        float[] constrained = _constraint.Apply(polygon, center, 2);
+        var radius = 2;
+        
+        float[] buffer = new float[128];
+        Span<float> constrained = _constraint.Apply(polygon, center, radius, buffer);
 
         Assert.That(constrained.Length, Is.EqualTo(expectedSize));
 
@@ -73,10 +83,13 @@ public class PolygonByCircleConstraintTest
         int expectedSize = 9 * 3;
         float[] polygon = { -4, 0, 0, -3, 0, 3, 2, 0, 3, 3, 0, -3, -2, 0, -4 };
         RcVec3f center = new RcVec3f(-2, 0, -1);
-        float[] constrained = _constraint.Apply(polygon, center, 3);
+        var radius = 3;
+        
+        float[] buffer = new float[128];
+        Span<float> constrained = _constraint.Apply(polygon, center, radius, buffer);
 
         Assert.That(constrained.Length, Is.EqualTo(expectedSize));
-        Assert.That(constrained, Is.SupersetOf(new[] { -2f, 0f, -4f, -4f, 0f, 0f, -3.4641016f, 0.0f, 1.60769534f, -2.0f, 0.0f, 2.0f }));
+        Assert.That(constrained.ToArray(), Is.SupersetOf(new[] { -2f, 0f, -4f, -4f, 0f, 0f, -3.4641016f, 0.0f, 1.60769534f, -2.0f, 0.0f, 2.0f }));
     }
 
     [Test]
@@ -85,9 +98,12 @@ public class PolygonByCircleConstraintTest
         int expectedSize = 7 * 3;
         float[] polygon = { -4, 0, 0, -3, 0, 3, 2, 0, 3, 3, 0, -3, -2, 0, -4 };
         RcVec3f center = new RcVec3f(4, 0, 0);
-        float[] constrained = _constraint.Apply(polygon, center, 4);
+        var radius = 4;
+        
+        float[] buffer = new float[128];
+        Span<float> constrained = _constraint.Apply(polygon, center, radius, buffer);
 
         Assert.That(constrained.Length, Is.EqualTo(expectedSize));
-        Assert.That(constrained, Is.SupersetOf(new[] { 1.53589869f, 0f, 3f, 2f, 0f, 3f, 3f, 0f, -3f }));
+        Assert.That(constrained.ToArray(), Is.SupersetOf(new[] { 1.53589869f, 0f, 3f, 2f, 0f, 3f, 3f, 0f, -3f }));
     }
 }