Add triangulation of polygon

FieldVisualizer/Entities/Values/Primitives/ITrianglePrimitive.cs

@@ -0,0 +1,16 @@
+using StructureHelperCommon.Models.Shapes;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace FieldVisualizer.Entities.Values.Primitives
+{
+    public interface ITrianglePrimitive : IValuePrimitive
+    {
+        IPoint2D Point1 { get; set; }
+        IPoint2D Point2 { get; set; }
+        IPoint2D Point3 { get; set; }
+    }
+}

FieldVisualizer/Entities/Values/Primitives/TrianglePrimitive.cs

@@ -0,0 +1,31 @@
+using StructureHelperCommon.Models.Shapes;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace FieldVisualizer.Entities.Values.Primitives
+{
+    public class TrianglePrimitive : ITrianglePrimitive
+    {
+        public double Value { get; set; }
+
+        public IPoint2D Point1 { get; set; }
+        public IPoint2D Point2 { get; set; }
+        public IPoint2D Point3 { get; set; }
+
+        // --- Computed properties ---
+
+        // Centroid (geometric center)
+        public double CenterX => (Point1.X + Point2.X + Point3.X) / 3.0;
+        public double CenterY => (Point1.Y + Point2.Y + Point3.Y) / 3.0;
+
+        // Triangle area using determinant formula
+        public double Area =>
+            0.5 * Math.Abs(
+                (Point2.X - Point1.X) * (Point3.Y - Point1.Y) -
+                (Point3.X - Point1.X) * (Point2.Y - Point1.Y)
+            );
+    }
+}