add matrix helper

thermion_dart/lib/thermion_dart/matrix_helper.dart

@@ -0,0 +1,37 @@
+// Helper function to convert double4x4 to Matrix4
+import 'package:thermion_dart/thermion_dart/compatibility/native/thermion_dart.g.dart';
+import 'package:vector_math/vector_math_64.dart';
+import 'dart:ffi';
+
+Matrix4 double4x4ToMatrix4(double4x4 mat) {
+  return Matrix4.fromList([
+    mat.col1[0],
+    mat.col1[1],
+    mat.col1[2],
+    mat.col1[3],
+    mat.col2[0],
+    mat.col2[1],
+    mat.col2[2],
+    mat.col2[3],
+    mat.col3[0],
+    mat.col3[1],
+    mat.col3[2],
+    mat.col3[3],
+    mat.col4[0],
+    mat.col4[1],
+    mat.col4[2],
+    mat.col4[3],
+  ]);
+}
+
+double4x4 matrix4ToDouble4x4(Matrix4 mat, double4x4 out) {
+  
+  for (int i = 0; i < 4; i++) {
+    out.col1[i] = mat.storage[i];
+    out.col2[i] = mat.storage[i + 4];
+    out.col3[i] = mat.storage[i + 8];
+    out.col4[i] = mat.storage[i + 12];
+  }
+  
+  return out;
+}