Added Math::Mod method

Eule/Math.cpp

@@ -75,5 +75,24 @@ bool Math::RandomChance(const double chance)
 	return Random() <= chance;
 }
 
+int Math::Mod(const int numerator, const int denominator)
+{
+	if (denominator == 0)
+		throw std::logic_error("Divide by zero");
+
+	// Quick optimizations:
+
+	// -> 0/n is always 0
+	if (numerator == 0)
+		return 0;
+
+	// -> operator% works for a > 0 && b > 0
+	if (denominator > 0 && numerator > 0)
+		return numerator % denominator;
+
+	// Else: generalized formula
+	return (denominator + (numerator % denominator)) % denominator;
+}
+
 std::mt19937 Math::rng;
 bool Math::isRngInitialized = true;

Eule/Math.h

@@ -1,5 +1,6 @@
 #pragma once
 #include <random>
+#include <stdexcept>
 
 namespace Eule
 {
@@ -26,6 +27,10 @@ namespace Eule
 		//! Compares two double values with a given accuracy
 		[[nodiscard]] static constexpr bool Similar(const double a, const double b, const double epsilon = 0.00001);
 		
+		//! Will compute the actual modulo of a fraction. The % operator returns bs for n<0.
+		//! May throw divide-by-zero std::logic_error
+		[[nodiscard]] static int Mod(const int numerator, const int denominator);
+		
 		//! Will return a random double between `0` and `1`
 		static double Random();
 

Test/Math__Mod.cpp

@@ -0,0 +1,83 @@
+#include "CppUnitTest.h"
+#include "../Eule/Math.h"
+#include <stdexcept>
+
+using namespace Microsoft::VisualStudio::CppUnitTestFramework;
+using namespace Eule;
+
+/** Equivalence classes:
+* a -> numerator
+* b -> denominator
+*		-- a > 0 && b > 0
+*		-- a < 0 && b > 0
+*		-- a > 0 && b < 0
+*		-- a < 0 && b < 0
+* 
+*		-- a > 0 && b = 0
+*		-- a = 0 && b > 0
+* *		-- a < 0 && b = 0
+*		-- a = 0 && b < 0
+*		-- a = 0 && b = 0
+*/
+
+namespace _Math
+{
+	TEST_CLASS(_Mod)
+	{
+	public:
+		// a > 0 && b > 0
+		TEST_METHOD(a_gt_0_and_b_gt_0)
+		{
+			Assert::AreEqual(7, Math::Mod(199, 32));
+			return;
+		}
+
+		// a < 0 && b > 0
+		TEST_METHOD(a_lt_0_and_b_gt_0)
+		{
+			Assert::AreEqual(25, Math::Mod(-199, 32));
+			return;
+		}
+
+		// a > 0 && b < 0
+		TEST_METHOD(a_gt_0_and_b_lt_0)
+		{
+			Assert::AreEqual(-25, Math::Mod(199, -32));
+			return;
+		}
+
+		// a > 0 && b = 0
+		TEST_METHOD(a_gt_0_and_b_eq_0)
+		{
+			// Exppect divide-by-zero
+			Assert::ExpectException<std::logic_error&>([]() {
+				Assert::AreEqual(0, Math::Mod(199, 0));
+			});
+			return;
+		}
+
+		// a = 0 && b > 0
+		TEST_METHOD(a_eq_0_and_b_gt_0)
+		{
+			Assert::AreEqual(0, Math::Mod(0, 32));
+			return;
+		}
+
+		// a < 0 && b = 0
+		TEST_METHOD(a_lt_0_and_b_eq_0)
+		{
+			// Exppect divide-by-zero
+			Assert::ExpectException<std::logic_error&>([]() {
+				Assert::AreEqual(0, Math::Mod(-199, 0));
+				});
+			return;
+		}
+
+		// a = 0 && b < 0
+		TEST_METHOD(a_eq_0_and_b_lt_0)
+		{
+			Assert::AreEqual(0, Math::Mod(0, -32));
+			return;
+		}
+	};
+}

Test/_Test_Eule.vcxproj

@@ -33,6 +33,7 @@
     <ClCompile Include="Math_RandomInteger.cpp" />
     <ClCompile Include="Math_RandomIntRange.cpp" />
     <ClCompile Include="Math_Similar.cpp" />
+    <ClCompile Include="Math__Mod.cpp" />
     <ClCompile Include="Math__Oscillate.cpp" />
     <ClCompile Include="Math__RandomRange.cpp" />
     <ClCompile Include="Matrix4x4.cpp" />

Test/_Test_Eule.vcxproj.filters

@@ -75,5 +75,8 @@
     <ClCompile Include="TrapazoidalPrismCollider.cpp">
       <Filter>Tests</Filter>
     </ClCompile>
+    <ClCompile Include="Math__Mod.cpp">
+      <Filter>Tests\Math</Filter>
+    </ClCompile>
   </ItemGroup>
 </Project>