vcmi: make int3 as constexpr class

This allows us to calculate distances and check const vector validity
at compile time

Global.h

@@ -746,6 +746,12 @@ namespace vstd
 		}
 		return std::to_string(number) + *iter;
 	}
+	
+	///compile-time version of std::abs for ints for int3, in clang++15 std::abs is constexpr
+	static constexpr int abs(int i) {
+		if(i < 0) return -i;
+		return i;
+	}
 }
 using vstd::operator-=;
 

lib/int3.h

@@ -18,48 +18,41 @@ public:
 	si32 x, y, z;
 
 	//c-tor: x, y, z initialized to 0
-	int3() : x(0), y(0), z(0) {} // I think that x, y, z should be left uninitialized.
+	constexpr int3() : x(0), y(0), z(0) {} // I think that x, y, z should be left uninitialized.
 	//c-tor: x, y, z initialized to i
-	explicit int3(const si32 i) : x(i), y(i), z(i) {}
+	explicit constexpr int3(const si32 i) : x(i), y(i), z(i) {}
 	//c-tor: x, y, z initialized to X, Y, Z
-	int3(const si32 X, const si32 Y, const si32 Z) : x(X), y(Y), z(Z) {}
-	int3(const int3 & c) : x(c.x), y(c.y), z(c.z) {} // Should be set to default (C++11)?
+	constexpr int3(const si32 X, const si32 Y, const si32 Z) : x(X), y(Y), z(Z) {}
+	constexpr int3(const int3 & c) = default;
 
-	int3 & operator=(const int3 & c) // Should be set to default (C++11)?
-	{
-		x = c.x;
-		y = c.y;
-		z = c.z;
-
-		return *this;
-	}
-	int3 operator-() const { return int3(-x, -y, -z); }
+	constexpr int3 & operator=(const int3 & c) = default;
+	constexpr int3 operator-() const { return int3(-x, -y, -z); }
 
-	int3 operator+(const int3 & i) const { return int3(x + i.x, y + i.y, z + i.z); }
-	int3 operator-(const int3 & i) const { return int3(x - i.x, y - i.y, z - i.z); }
+	constexpr int3 operator+(const int3 & i) const { return int3(x + i.x, y + i.y, z + i.z); }
+	constexpr int3 operator-(const int3 & i) const { return int3(x - i.x, y - i.y, z - i.z); }
 	//returns int3 with coordinates increased by given number
-	int3 operator+(const si32 i) const { return int3(x + i, y + i, z + i); }
+	constexpr int3 operator+(const si32 i) const { return int3(x + i, y + i, z + i); }
 	//returns int3 with coordinates decreased by given number
-	int3 operator-(const si32 i) const { return int3(x - i, y - i, z - i); }
+	constexpr int3 operator-(const si32 i) const { return int3(x - i, y - i, z - i); }
 
 	//returns int3 with coordinates multiplied by given number
-	int3 operator*(const double i) const { return int3((int)(x * i), (int)(y * i), (int)(z * i)); }
+	constexpr int3 operator*(const double i) const { return int3((int)(x * i), (int)(y * i), (int)(z * i)); }
 	//returns int3 with coordinates divided by given number
-	int3 operator/(const double i) const { return int3((int)(x / i), (int)(y / i), (int)(z / i)); }
+	constexpr int3 operator/(const double i) const { return int3((int)(x / i), (int)(y / i), (int)(z / i)); }
 
 	//returns int3 with coordinates multiplied by given number
-	int3 operator*(const si32 i) const { return int3(x * i, y * i, z * i); }
+	constexpr int3 operator*(const si32 i) const { return int3(x * i, y * i, z * i); }
 	//returns int3 with coordinates divided by given number
-	int3 operator/(const si32 i) const { return int3(x / i, y / i, z / i); }
+	constexpr int3 operator/(const si32 i) const { return int3(x / i, y / i, z / i); }
 
-	int3 & operator+=(const int3 & i)
+	constexpr int3 & operator+=(const int3 & i)
 	{
 		x += i.x;
 		y += i.y;
 		z += i.z;
 		return *this;
 	}
-	int3 & operator-=(const int3 & i)
+	constexpr int3 & operator-=(const int3 & i)
 	{
 		x -= i.x;
 		y -= i.y;
@@ -68,7 +61,7 @@ public:
 	}
 
 	//increases all coordinates by given number
-	int3 & operator+=(const si32 i)
+	constexpr int3 & operator+=(const si32 i)
 	{
 		x += i;
 		y += i;
@@ -76,7 +69,7 @@ public:
 		return *this;
 	}
 	//decreases all coordinates by given number
-	int3 & operator-=(const si32 i)
+	constexpr int3 & operator-=(const si32 i)
 	{
 		x -= i;
 		y -= i;
@@ -84,10 +77,10 @@ public:
 		return *this;
 	}
 
-	bool operator==(const int3 & i) const { return (x == i.x && y == i.y && z == i.z); }
-	bool operator!=(const int3 & i) const { return (x != i.x || y != i.y || z != i.z); }
+	constexpr bool operator==(const int3 & i) const { return (x == i.x && y == i.y && z == i.z); }
+	constexpr bool operator!=(const int3 & i) const { return (x != i.x || y != i.y || z != i.z); }
 
-	bool operator<(const int3 & i) const
+	constexpr bool operator<(const int3 & i) const
 	{
 		if (z < i.z)
 			return true;
@@ -130,7 +123,7 @@ public:
 	}
 
 	//returns squared distance on Oxy plane (z coord is not used)
-	ui32 dist2dSQ(const int3 & o) const
+	constexpr ui32 dist2dSQ(const int3 & o) const
 	{
 		const si32 dx = (x - o.x);
 		const si32 dy = (y - o.y);
@@ -142,17 +135,17 @@ public:
 		return std::sqrt((double)dist2dSQ(o));
 	}
 	//manhattan distance used for patrol radius (z coord is not used)
-	double mandist2d(const int3 & o) const
+	constexpr double mandist2d(const int3 & o) const
 	{
-		return abs(o.x - x) + abs(o.y - y);
+		return vstd::abs(o.x - x) + vstd::abs(o.y - y);
 	}
 	//chebyshev distance used for ambient sounds (z coord is not used)
-	double chebdist2d(const int3 & o) const
+	constexpr double chebdist2d(const int3 & o) const
 	{
-		return std::max(std::abs(o.x - x), std::abs(o.y - y));
+		return std::max(vstd::abs(o.x - x), vstd::abs(o.y - y));
 	}
 
-	bool areNeighbours(const int3 & o) const
+	constexpr bool areNeighbours(const int3 & o) const
 	{
 		return (dist2dSQ(o) < 4) && (z == o.z);
 	}
@@ -169,7 +162,7 @@ public:
 		return result;
 	}
 
-	bool valid() const //Should be named "isValid"?
+	constexpr bool valid() const //Should be named "isValid"?
 	{
 		return z >= 0; //minimal condition that needs to be fulfilled for tiles in the map
 	}
@@ -182,7 +175,7 @@ public:
 		h & z;
 	}
 
-	static std::array<int3, 8> getDirs()
+	constexpr static std::array<int3, 8> getDirs()
 	{
 		return { { int3(0,1,0),int3(0,-1,0),int3(-1,0,0),int3(+1,0,0),
 			int3(1,1,0),int3(-1,1,0),int3(1,-1,0),int3(-1,-1,0) } };