✨ Add 'Displacement' type to represent coordinate deltas

Source/engine/displacement.hpp

@@ -0,0 +1,87 @@
+#pragma once
+
+#include <cmath>
+
+#include "direction.hpp"
+#include "utils/stdcompat/abs.hpp"
+
+namespace devilution {
+
+struct Displacement {
+	int deltaX;
+	int deltaY;
+
+	constexpr bool operator==(const Displacement &other) const
+	{
+		return deltaX == other.deltaX && deltaY == other.deltaY;
+	}
+
+	constexpr bool operator!=(const Displacement &other) const
+	{
+		return !(*this == other);
+	}
+
+	constexpr Displacement &operator+=(const Displacement &displacement)
+	{
+		deltaX += displacement.deltaX;
+		deltaY += displacement.deltaY;
+		return *this;
+	}
+
+	constexpr Displacement &operator-=(const Displacement &displacement)
+	{
+		deltaX -= displacement.deltaX;
+		deltaY -= displacement.deltaY;
+		return *this;
+	}
+
+	constexpr Displacement &operator*=(const int factor)
+	{
+		deltaX *= factor;
+		deltaY *= factor;
+		return *this;
+	}
+
+	constexpr Displacement &operator*=(const float factor)
+	{
+		deltaX *= factor;
+		deltaY *= factor;
+		return *this;
+	}
+
+	constexpr friend Displacement operator+(Displacement a, Displacement b)
+	{
+		a += b;
+		return a;
+	}
+
+	constexpr friend Displacement operator-(Displacement a, Displacement b)
+	{
+		a -= b;
+		return a;
+	}
+
+	constexpr friend Displacement operator*(Displacement a, const int factor)
+	{
+		a *= factor;
+		return a;
+	}
+
+	constexpr friend Displacement operator*(Displacement a, const float factor)
+	{
+		a *= factor;
+		return a;
+	}
+
+	constexpr friend Displacement operator-(const Displacement &a)
+	{
+		return { -a.deltaX, -a.deltaY };
+	}
+
+	constexpr friend Displacement abs(Displacement a)
+	{
+		return { abs(a.deltaX), abs(a.deltaY) };
+	}
+};
+
+} // namespace devilution