diff --git a/src/DotRecast.Core/RcMatrix4x4f.cs b/src/DotRecast.Core/RcMatrix4x4f.cs
index 2a81478..26c2d00 100644
--- a/src/DotRecast.Core/RcMatrix4x4f.cs
+++ b/src/DotRecast.Core/RcMatrix4x4f.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Numerics;
 
 namespace DotRecast.Core
 {
@@ -12,22 +13,22 @@ namespace DotRecast.Core
             0f, 0f, 0f, 1f
         );
 
-        public float M11;
-        public float M12;
-        public float M13;
-        public float M14;
-        public float M21;
-        public float M22;
-        public float M23;
-        public float M24;
-        public float M31;
-        public float M32;
-        public float M33;
-        public float M34;
-        public float M41;
-        public float M42;
-        public float M43;
-        public float M44;
+        public float M11; // 0
+        public float M12; // 1
+        public float M13; // 2
+        public float M14; // 3
+        public float M21; // 4
+        public float M22; // 5
+        public float M23; // 6
+        public float M24; // 7 
+        public float M31; // 8
+        public float M32; // 9
+        public float M33; // 10
+        public float M34; // 11
+        public float M41; // 12
+        public float M42; // 13
+        public float M43; // 14
+        public float M44; // 15
 
         public RcMatrix4x4f(
             float m11, float m12, float m13, float m14,
@@ -56,6 +57,48 @@ namespace DotRecast.Core
             M44 = m44;
         }
 
+        public RcMatrix4x4f(float[] m)
+        {
+            M11 = m[0];
+            M12 = m[1];
+            M13 = m[2];
+            M14 = m[3];
+            M21 = m[4];
+            M22 = m[5];
+            M23 = m[6];
+            M24 = m[7];
+            M31 = m[8];
+            M32 = m[9];
+            M33 = m[10];
+            M34 = m[11];
+            M41 = m[12];
+            M42 = m[13];
+            M43 = m[14];
+            M44 = m[15];
+        }
+
+
+        public void CopyTo(float[] m)
+        {
+            m[0] = M11;
+            m[1] = M12;
+            m[2] = M13;
+            m[3] = M14;
+            m[4] = M21;
+            m[5] = M22;
+            m[6] = M23;
+            m[7] = M24;
+            m[8] = M31;
+            m[9] = M32;
+            m[10] = M33;
+            m[11] = M34;
+            m[12] = M41;
+            m[13] = M42;
+            m[14] = M43;
+            m[15] = M44;
+        }
+
+
         public static RcMatrix4x4f Identity => _identity;
 
         public readonly bool IsIdentity =>
@@ -105,7 +148,34 @@ namespace DotRecast.Core
             return dest;
         }
 
-        public static RcMatrix4x4f Rotate(float a, float x, float y, float z)
+        public static RcMatrix4x4f Mul(float[] left, float[] right)
+        {
+            float m00 = left[0] * right[0] + left[4] * right[1] + left[8] * right[2] + left[12] * right[3];
+            float m01 = left[1] * right[0] + left[5] * right[1] + left[9] * right[2] + left[13] * right[3];
+            float m02 = left[2] * right[0] + left[6] * right[1] + left[10] * right[2] + left[14] * right[3];
+            float m03 = left[3] * right[0] + left[7] * right[1] + left[11] * right[2] + left[15] * right[3];
+            float m10 = left[0] * right[4] + left[4] * right[5] + left[8] * right[6] + left[12] * right[7];
+            float m11 = left[1] * right[4] + left[5] * right[5] + left[9] * right[6] + left[13] * right[7];
+            float m12 = left[2] * right[4] + left[6] * right[5] + left[10] * right[6] + left[14] * right[7];
+            float m13 = left[3] * right[4] + left[7] * right[5] + left[11] * right[6] + left[15] * right[7];
+            float m20 = left[0] * right[8] + left[4] * right[9] + left[8] * right[10] + left[12] * right[11];
+            float m21 = left[1] * right[8] + left[5] * right[9] + left[9] * right[10] + left[13] * right[11];
+            float m22 = left[2] * right[8] + left[6] * right[9] + left[10] * right[10] + left[14] * right[11];
+            float m23 = left[3] * right[8] + left[7] * right[9] + left[11] * right[10] + left[15] * right[11];
+            float m30 = left[0] * right[12] + left[4] * right[13] + left[8] * right[14] + left[12] * right[15];
+            float m31 = left[1] * right[12] + left[5] * right[13] + left[9] * right[14] + left[13] * right[15];
+            float m32 = left[2] * right[12] + left[6] * right[13] + left[10] * right[14] + left[14] * right[15];
+            float m33 = left[3] * right[12] + left[7] * right[13] + left[11] * right[14] + left[15] * right[15];
+
+            return new RcMatrix4x4f(
+                m00, m01, m02, m03,
+                m10, m11, m12, m13,
+                m20, m21, m22, m23,
+                m30, m31, m32, m33
+            );
+        }
+
+        public static RcMatrix4x4f CreateFromRotate(float a, float x, float y, float z)
         {
             var matrix = new RcMatrix4x4f();
             a = (float)(a * Math.PI / 180.0); // convert to radians
diff --git a/src/DotRecast.Recast.Demo/Draw/DebugDraw.cs b/src/DotRecast.Recast.Demo/Draw/DebugDraw.cs
index 7ffee95..28b7998 100644
--- a/src/DotRecast.Recast.Demo/Draw/DebugDraw.cs
+++ b/src/DotRecast.Recast.Demo/Draw/DebugDraw.cs
@@ -19,6 +19,7 @@ freely, subject to the following restrictions:
 */
 
 using System;
+using System.Numerics;
 using Silk.NET.OpenGL;
 using DotRecast.Core;
 using DotRecast.Recast.Toolset.Builder;
@@ -638,15 +639,17 @@ public class DebugDraw
 
     public float[] ViewMatrix(RcVec3f cameraPos, float[] cameraEulers)
     {
-        float[] rx = GLU.Build_4x4_rotation_matrix(cameraEulers[0], 1, 0, 0);
-        float[] ry = GLU.Build_4x4_rotation_matrix(cameraEulers[1], 0, 1, 0);
-        float[] r = GLU.Mul(rx, ry);
-        float[] t = new float[16];
-        t[0] = t[5] = t[10] = t[15] = 1;
-        t[12] = -cameraPos.x;
-        t[13] = -cameraPos.y;
-        t[14] = -cameraPos.z;
-        _viewMatrix = GLU.Mul(r, t);
+        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 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(_viewMatrix);
         UpdateFrustum();
         return _viewMatrix;
@@ -665,19 +668,13 @@ public class DebugDraw
 
     private void UpdateFrustum()
     {
-        float[] vpm = GLU.Mul(_projectionMatrix, _viewMatrix);
-        // left
-        NormalizePlane(vpm[0 + 3] + vpm[0 + 0], vpm[4 + 3] + vpm[4 + 0], vpm[8 + 3] + vpm[8 + 0], vpm[12 + 3] + vpm[12 + 0], ref frustumPlanes[0]);
-        // right
-        NormalizePlane(vpm[0 + 3] - vpm[0 + 0], vpm[4 + 3] - vpm[4 + 0], vpm[8 + 3] - vpm[8 + 0], vpm[12 + 3] - vpm[12 + 0], ref frustumPlanes[1]);
-        // top
-        NormalizePlane(vpm[0 + 3] - vpm[0 + 1], vpm[4 + 3] - vpm[4 + 1], vpm[8 + 3] - vpm[8 + 1], vpm[12 + 3] - vpm[12 + 1], ref frustumPlanes[2]);
-        // bottom
-        NormalizePlane(vpm[0 + 3] + vpm[0 + 1], vpm[4 + 3] + vpm[4 + 1], vpm[8 + 3] + vpm[8 + 1], vpm[12 + 3] + vpm[12 + 1], ref frustumPlanes[3]);
-        // near
-        NormalizePlane(vpm[0 + 3] + vpm[0 + 2], vpm[4 + 3] + vpm[4 + 2], vpm[8 + 3] + vpm[8 + 2], vpm[12 + 3] + vpm[12 + 2], ref frustumPlanes[4]);
-        // far
-        NormalizePlane(vpm[0 + 3] - vpm[0 + 2], vpm[4 + 3] - vpm[4 + 2], vpm[8 + 3] - vpm[8 + 2], vpm[12 + 3] - vpm[12 + 2], ref frustumPlanes[5]);
+        var vpm = RcMatrix4x4f.Mul(_projectionMatrix, _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
+        NormalizePlane(vpm.M14 + vpm.M12, vpm.M24 + vpm.M22, vpm.M34 + vpm.M32, vpm.M44 + vpm.M42, ref frustumPlanes[3]); // bottom
+        NormalizePlane(vpm.M14 + vpm.M13, vpm.M24 + vpm.M23, vpm.M34 + vpm.M33, vpm.M44 + vpm.M43, ref frustumPlanes[4]); // near
+        NormalizePlane(vpm.M14 - vpm.M13, vpm.M24 - vpm.M23, vpm.M34 - vpm.M33, vpm.M44 - vpm.M43, ref frustumPlanes[5]); // far
     }
 
     private void NormalizePlane(float px, float py, float pz, float pw, ref float[] plane)
diff --git a/src/DotRecast.Recast.Demo/Draw/GLU.cs b/src/DotRecast.Recast.Demo/Draw/GLU.cs
index a134afb..2c228e8 100644
--- a/src/DotRecast.Recast.Demo/Draw/GLU.cs
+++ b/src/DotRecast.Recast.Demo/Draw/GLU.cs
@@ -31,8 +31,7 @@ public static class GLU
         return projectionMatrix;
     }
 
-    public static void GlhPerspectivef2(float[] matrix, float fovyInDegrees, float aspectRatio, float znear,
-        float zfar)
+    public static void GlhPerspectivef2(float[] matrix, float fovyInDegrees, float aspectRatio, float znear, float zfar)
     {
         float ymax, xmax;
         ymax = (float)(znear * Math.Tan(fovyInDegrees * Math.PI / 360.0));
@@ -40,8 +39,7 @@ public static class GLU
         GlhFrustumf2(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(float[] matrix, float left, float right, float bottom, float top, float znear, float zfar)
     {
         float temp, temp2, temp3, temp4;
         temp = 2.0f * znear;
@@ -369,44 +367,6 @@ public static class GLU
         m[(c) * 4 + (r)] = v;
     }
 
-    public static float[] Build_4x4_rotation_matrix(float a, float x, float y, float z)
-    {
-        float[] matrix = new float[16];
-        a = (float)(a * Math.PI / 180.0); // convert to radians
-        float s = (float)Math.Sin(a);
-        float c = (float)Math.Cos(a);
-        float t = 1.0f - c;
-
-        float tx = t * x;
-        float ty = t * y;
-        float tz = t * z;
-
-        float sz = s * z;
-        float sy = s * y;
-        float sx = s * x;
-
-        matrix[0] = tx * x + c;
-        matrix[1] = tx * y + sz;
-        matrix[2] = tx * z - sy;
-        matrix[3] = 0;
-
-        matrix[4] = tx * y - sz;
-        matrix[5] = ty * y + c;
-        matrix[6] = ty * z + sx;
-        matrix[7] = 0;
-
-        matrix[8] = tx * z + sy;
-        matrix[9] = ty * z - sx;
-        matrix[10] = tz * z + c;
-        matrix[11] = 0;
-
-        matrix[12] = 0;
-        matrix[13] = 0;
-        matrix[14] = 0;
-        matrix[15] = 1;
-        return matrix;
-    }
-
     public static float[] Mul(float[] left, float[] right)
     {
         float m00 = left[0] * right[0] + left[4] * right[1] + left[8] * right[2] + left[12] * right[3];
diff --git a/src/DotRecast.Recast.Demo/Draw/ModernOpenGLDraw.cs b/src/DotRecast.Recast.Demo/Draw/ModernOpenGLDraw.cs
index 23160dc..5721e90 100644
--- a/src/DotRecast.Recast.Demo/Draw/ModernOpenGLDraw.cs
+++ b/src/DotRecast.Recast.Demo/Draw/ModernOpenGLDraw.cs
@@ -317,12 +317,12 @@ public class ModernOpenGLDraw : IOpenGLDraw
 
     public void ProjectionMatrix(float[] projectionMatrix)
     {
-        this._projectionMatrix = projectionMatrix;
+        _projectionMatrix = projectionMatrix;
     }
 
     public void ViewMatrix(float[] viewMatrix)
     {
-        this._viewMatrix = viewMatrix;
+        _viewMatrix = viewMatrix;
     }
 
     public void Fog(float start, float end)
diff --git a/src/DotRecast.Recast.Toolset/Tools/RcDynamicUpdateTool.cs b/src/DotRecast.Recast.Toolset/Tools/RcDynamicUpdateTool.cs
index e14fe4c..ff4efd5 100644
--- a/src/DotRecast.Recast.Toolset/Tools/RcDynamicUpdateTool.cs
+++ b/src/DotRecast.Recast.Toolset/Tools/RcDynamicUpdateTool.cs
@@ -238,7 +238,7 @@ namespace DotRecast.Recast.Toolset.Tools
                 SampleAreaModifications.SAMPLE_POLYAREA_TYPE_ROAD, walkableClimb);
             var roofUp = RcVec3f.Zero;
             RcVec3f roofExtent = RcVec3f.Of(4.5f, 4.5f, 8f);
-            var rx = RcMatrix4x4f.Rotate(45, forward.x, forward.y, forward.z);
+            var rx = RcMatrix4x4f.CreateFromRotate(45, forward.x, forward.y, forward.z);
             roofUp = MulMatrixVector(ref roofUp, rx, baseUp);
             RcVec3f roofCenter = RcVec3f.Of(p.x, p.y + 6, p.z);
             BoxCollider roof = new BoxCollider(roofCenter, Detour.Dynamic.Colliders.BoxCollider.GetHalfEdges(roofUp, forward, roofExtent),
@@ -297,8 +297,8 @@ namespace DotRecast.Recast.Toolset.Tools
 
         private float[] TransformVertices(RcVec3f p, DemoInputGeomProvider geom, float ax)
         {
-            var rx = RcMatrix4x4f.Rotate((float)random.NextDouble() * ax, 1, 0, 0);
-            var ry = RcMatrix4x4f.Rotate((float)random.NextDouble() * 360, 0, 1, 0);
+            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);
             float[] verts = new float[geom.vertices.Length];
             RcVec3f v = new RcVec3f();