Create FibonacciNode.cs

ProjectObsidian/ProtoFlux/Math/FibonacciNode.cs

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+using System;
+using Elements.Core;
+using FrooxEngine.ProtoFlux;
+using ProtoFlux.Core;
+using ProtoFlux.Runtimes.Execution;
+
+namespace ProtoFlux.Runtimes.Execution.Nodes.Obsidian.Math
+{
+    [NodeCategory("Obsidian/Math")]
+    [NodeName("Fibonacci")]
+    public class FibonacciNode : ValueFunctionNode<FrooxEngineContext, int>
+    {
+        public ValueInput<int> Input;
+
+        protected override int Compute(FrooxEngineContext context)
+        {
+            int n = Input.Evaluate(context);
+            return Fibonacci(n);
+        }
+
+        private int Fibonacci(int n)
+        {
+            if (n < 0)
+                throw new ArgumentException("Negative numbers are not allowed.");
+            if (n == 0)
+                return 0;
+            if (n == 1)
+                return 1;
+
+            int a = 0, b = 1, temp;
+            for (int i = 2; i <= n; i++)
+            {
+                temp = a + b;
+                a = b;
+                b = temp;
+            }
+            return b;
+        }
+    }
+}