diff --git a/src/DotRecast.Core/RcMatrix4x4f.cs b/src/DotRecast.Core/RcMatrix4x4f.cs
index 2cfd032..65f90f0 100644
--- a/src/DotRecast.Core/RcMatrix4x4f.cs
+++ b/src/DotRecast.Core/RcMatrix4x4f.cs
@@ -107,7 +107,7 @@ namespace DotRecast.Core
             M31 == 0f && M32 == 0f && M34 == 0f &&
             M41 == 0f && M42 == 0f && M43 == 0f;
 
-        public static RcMatrix4x4f Mul(RcMatrix4x4f left, RcMatrix4x4f right)
+        public static RcMatrix4x4f Mul(ref RcMatrix4x4f left, ref RcMatrix4x4f right)
         {
             float m11 = left.M11 * right.M11 + left.M21 * right.M12 + left.M31 * right.M13 + left.M41 * right.M14;
             float m12 = left.M12 * right.M11 + left.M22 * right.M12 + left.M32 * right.M13 + left.M42 * right.M14;
diff --git a/src/DotRecast.Recast.Demo/Draw/DebugDraw.cs b/src/DotRecast.Recast.Demo/Draw/DebugDraw.cs
index 34f525c..443ca3d 100644
--- a/src/DotRecast.Recast.Demo/Draw/DebugDraw.cs
+++ b/src/DotRecast.Recast.Demo/Draw/DebugDraw.cs
@@ -303,8 +303,8 @@ public class DebugDraw
     private bool circleInit = false;
     private const int CIRCLE_NUM_SEG = 40;
     private readonly float[] circeDir = new float[CIRCLE_NUM_SEG * 2];
-    private float[] _viewMatrix = new float[16];
-    private readonly float[] _projectionMatrix = new float[16];
+    private RcMatrix4x4f _viewMatrix = new();
+    private RcMatrix4x4f _projectionMatrix = new();
 
     public void AppendCircle(float x, float y, float z, float r, int col)
     {
@@ -628,10 +628,10 @@ public class DebugDraw
     }
 
 
-    public float[] ProjectionMatrix(float fovy, float aspect, float near, float far)
+    public RcMatrix4x4f ProjectionMatrix(float fovy, float aspect, float near, float far)
     {
-        GLU.GlhPerspectivef2(_projectionMatrix, fovy, aspect, near, far);
-        GetOpenGlDraw().ProjectionMatrix(_projectionMatrix);
+        GLU.GlhPerspectivef2(ref _projectionMatrix, fovy, aspect, near, far);
+        GetOpenGlDraw().ProjectionMatrix(ref _projectionMatrix);
         UpdateFrustum();
         return _projectionMatrix;
     }
@@ -640,18 +640,17 @@ public class DebugDraw
     {
         var rx = RcMatrix4x4f.CreateFromRotate(cameraEulers[0], 1, 0, 0);
         var ry = RcMatrix4x4f.CreateFromRotate(cameraEulers[1], 0, 1, 0);
-        var r = RcMatrix4x4f.Mul(rx, ry);
+        var r = RcMatrix4x4f.Mul(ref rx, ref ry);
 
         var t = new RcMatrix4x4f();
         t.M11 = t.M22 = t.M33 = t.M44 = 1;
         t.M41 = -cameraPos.x;
         t.M42 = -cameraPos.y;
         t.M43 = -cameraPos.z;
-        var mul = RcMatrix4x4f.Mul(r, t);
-        mul.CopyTo(_viewMatrix);
-        GetOpenGlDraw().ViewMatrix(ref mul);
+        _viewMatrix = RcMatrix4x4f.Mul(ref r, ref t);
+        GetOpenGlDraw().ViewMatrix(ref _viewMatrix);
         UpdateFrustum();
-        return mul;
+        return _viewMatrix;
     }
 
 
@@ -667,7 +666,7 @@ public class DebugDraw
 
     private void UpdateFrustum()
     {
-        var vpm = RcMatrix4x4f.Mul(_projectionMatrix, _viewMatrix);
+        var vpm = RcMatrix4x4f.Mul(ref _projectionMatrix, ref _viewMatrix);
         NormalizePlane(vpm.M14 + vpm.M11, vpm.M24 + vpm.M21, vpm.M34 + vpm.M31, vpm.M44 + vpm.M41, ref frustumPlanes[0]); // left
         NormalizePlane(vpm.M14 - vpm.M11, vpm.M24 - vpm.M21, vpm.M34 - vpm.M31, vpm.M44 - vpm.M41, ref frustumPlanes[1]); // right
         NormalizePlane(vpm.M14 - vpm.M12, vpm.M24 - vpm.M22, vpm.M34 - vpm.M32, vpm.M44 - vpm.M42, ref frustumPlanes[2]); // top
diff --git a/src/DotRecast.Recast.Demo/Draw/GLU.cs b/src/DotRecast.Recast.Demo/Draw/GLU.cs
index 2c228e8..efc7e37 100644
--- a/src/DotRecast.Recast.Demo/Draw/GLU.cs
+++ b/src/DotRecast.Recast.Demo/Draw/GLU.cs
@@ -23,45 +23,45 @@ namespace DotRecast.Recast.Demo.Draw;
 
 public static class GLU
 {
-    public static float[] GluPerspective(float fovy, float aspect, float near, float far)
+    public static RcMatrix4x4f GluPerspective(float fovy, float aspect, float near, float far)
     {
-        float[] projectionMatrix = new float[16];
-        GlhPerspectivef2(projectionMatrix, fovy, aspect, near, far);
+        var projectionMatrix = new RcMatrix4x4f();
+        GlhPerspectivef2(ref projectionMatrix, fovy, aspect, near, far);
         //GlLoadMatrixf(projectionMatrix);
         return projectionMatrix;
     }
 
-    public static void GlhPerspectivef2(float[] matrix, float fovyInDegrees, float aspectRatio, float znear, float zfar)
+    public static void GlhPerspectivef2(ref RcMatrix4x4f matrix, float fovyInDegrees, float aspectRatio, float znear, float zfar)
     {
         float ymax, xmax;
         ymax = (float)(znear * Math.Tan(fovyInDegrees * Math.PI / 360.0));
         xmax = ymax * aspectRatio;
-        GlhFrustumf2(matrix, -xmax, xmax, -ymax, ymax, znear, zfar);
+        GlhFrustumf2(ref matrix, -xmax, xmax, -ymax, ymax, znear, zfar);
     }
 
-    private static void GlhFrustumf2(float[] matrix, float left, float right, float bottom, float top, float znear, float zfar)
+    private static void GlhFrustumf2(ref RcMatrix4x4f matrix, float left, float right, float bottom, float top, float znear, float zfar)
     {
         float temp, temp2, temp3, temp4;
         temp = 2.0f * znear;
         temp2 = right - left;
         temp3 = top - bottom;
         temp4 = zfar - znear;
-        matrix[0] = temp / temp2;
-        matrix[1] = 0.0f;
-        matrix[2] = 0.0f;
-        matrix[3] = 0.0f;
-        matrix[4] = 0.0f;
-        matrix[5] = temp / temp3;
-        matrix[6] = 0.0f;
-        matrix[7] = 0.0f;
-        matrix[8] = (right + left) / temp2;
-        matrix[9] = (top + bottom) / temp3;
-        matrix[10] = (-zfar - znear) / temp4;
-        matrix[11] = -1.0f;
-        matrix[12] = 0.0f;
-        matrix[13] = 0.0f;
-        matrix[14] = (-temp * zfar) / temp4;
-        matrix[15] = 0.0f;
+        matrix.M11 = temp / temp2;
+        matrix.M12 = 0.0f;
+        matrix.M13 = 0.0f;
+        matrix.M14 = 0.0f;
+        matrix.M21 = 0.0f;
+        matrix.M22 = temp / temp3;
+        matrix.M23 = 0.0f;
+        matrix.M24 = 0.0f;
+        matrix.M31 = (right + left) / temp2;
+        matrix.M32 = (top + bottom) / temp3;
+        matrix.M33 = (-zfar - znear) / temp4;
+        matrix.M34 = -1.0f;
+        matrix.M41 = 0.0f;
+        matrix.M42 = 0.0f;
+        matrix.M43 = (-temp * zfar) / temp4;
+        matrix.M44 = 0.0f;
     }
 
     public static int GlhUnProjectf(float winx, float winy, float winz, float[] modelview, float[] projection, int[] viewport, ref RcVec3f objectCoordinate)
diff --git a/src/DotRecast.Recast.Demo/Draw/IOpenGLDraw.cs b/src/DotRecast.Recast.Demo/Draw/IOpenGLDraw.cs
index 60836f3..4b6e098 100644
--- a/src/DotRecast.Recast.Demo/Draw/IOpenGLDraw.cs
+++ b/src/DotRecast.Recast.Demo/Draw/IOpenGLDraw.cs
@@ -27,7 +27,7 @@ public interface IOpenGLDraw
 
     void Texture(GLCheckerTexture g_tex, bool state);
 
-    void ProjectionMatrix(float[] projectionMatrix);
+    void ProjectionMatrix(ref RcMatrix4x4f projectionMatrix);
 
     void ViewMatrix(ref RcMatrix4x4f viewMatrix);
 
diff --git a/src/DotRecast.Recast.Demo/Draw/ModernOpenGLDraw.cs b/src/DotRecast.Recast.Demo/Draw/ModernOpenGLDraw.cs
index da7b1ff..f942240 100644
--- a/src/DotRecast.Recast.Demo/Draw/ModernOpenGLDraw.cs
+++ b/src/DotRecast.Recast.Demo/Draw/ModernOpenGLDraw.cs
@@ -22,8 +22,8 @@ public class ModernOpenGLDraw : IOpenGLDraw
     private readonly ArrayBuffer<OpenGLVertex> vertices = new();
     private readonly ArrayBuffer<int> elements = new();
     private GLCheckerTexture _texture;
-    private float[] _viewMatrix = new float[16];
-    private float[] _projectionMatrix;
+    private readonly float[] _viewMatrix = new float[16];
+    private readonly float[] _projectionMatrix = new float[16];
     private int uniformUseTexture;
     private int uniformFog;
     private int uniformFogStart;
@@ -315,9 +315,9 @@ public class ModernOpenGLDraw : IOpenGLDraw
         }
     }
 
-    public void ProjectionMatrix(float[] projectionMatrix)
+    public void ProjectionMatrix(ref RcMatrix4x4f projectionMatrix)
     {
-        _projectionMatrix = projectionMatrix;
+        projectionMatrix.CopyTo(_projectionMatrix);
     }
 
     public void ViewMatrix(ref RcMatrix4x4f viewMatrix)
diff --git a/src/DotRecast.Recast.Demo/RecastDemo.cs b/src/DotRecast.Recast.Demo/RecastDemo.cs
index 8f359db..9565190 100644
--- a/src/DotRecast.Recast.Demo/RecastDemo.cs
+++ b/src/DotRecast.Recast.Demo/RecastDemo.cs
@@ -607,7 +607,7 @@ public class RecastDemo : IRecastDemoChannel
     {
         // Clear the screen
         dd.Clear();
-        projectionMatrix = dd.ProjectionMatrix(50f, (float)width / (float)height, 1.0f, camr);
+        dd.ProjectionMatrix(50f, (float)width / (float)height, 1.0f, camr).CopyTo(projectionMatrix);
         dd.ViewMatrix(cameraPos, cameraEulers).CopyTo(modelviewMatrix);
 
         dd.Fog(camr * 0.1f, camr * 1.25f);
diff --git a/src/DotRecast.Recast.Toolset/Tools/RcDynamicUpdateTool.cs b/src/DotRecast.Recast.Toolset/Tools/RcDynamicUpdateTool.cs
index ff4efd5..d62b7a5 100644
--- a/src/DotRecast.Recast.Toolset/Tools/RcDynamicUpdateTool.cs
+++ b/src/DotRecast.Recast.Toolset/Tools/RcDynamicUpdateTool.cs
@@ -299,7 +299,7 @@ namespace DotRecast.Recast.Toolset.Tools
         {
             var rx = RcMatrix4x4f.CreateFromRotate((float)random.NextDouble() * ax, 1, 0, 0);
             var ry = RcMatrix4x4f.CreateFromRotate((float)random.NextDouble() * 360, 0, 1, 0);
-            var m = RcMatrix4x4f.Mul(rx, ry);
+            var m = RcMatrix4x4f.Mul(ref rx, ref ry);
             float[] verts = new float[geom.vertices.Length];
             RcVec3f v = new RcVec3f();
             RcVec3f vr = new RcVec3f();