collision.cpp

#include <cmath>
#include <iostream>

struct vec {
	float x, y;

	vec(float x, float y) : x(x), y(y) {}
	friend std::ostream& operator<<(std::ostream &os, const vec &v);

	static float length(const vec &v) {
		return sqrt(v.x * v.x + v.y * v.y);
	}

	static vec normalize(const vec &v) {
		const auto l = vec::length(v);
		return l > 0.0f ? v / l : v;
	}

	vec operator*(const float &scala) const {
		return vec(this->x * scala, this->y * scala);
	}
	vec operator/(const float &scala) const {
		return vec(this->x / scala, this->y / scala);
	}
	vec operator+(const vec &other) const {
		return vec(this->x + other.x, this->y + other.y);
	}
	vec operator-(const vec &other) const {
		return vec(this->x - other.x, this->y - other.y);
	}
};
std::ostream& operator<<(std::ostream &os, const vec &v) {
	os << v.x << ", " << v.y;
	return os;
}
struct rect {
	vec pos, dim;

	rect(float x, float y, float w, float h) :
		pos(x, y), dim(w, h) {}

	float left() const { return pos.x; }
	float right() const { return pos.x + dim.x; }
	float top() const { return pos.y; }
	float bottom() const { return pos.y + dim.y; }
	vec center() const { return (pos + dim) * 0.5f; }
};

bool overlapping(const rect &a, const rect &b) {
	return !(
		a.left() > b.right() ||
		a.right() < b.left() ||
		a.top() > b.bottom() ||
		a.bottom() < b.top()
	);
}

void collision(const rect &a, const rect &b) {
	auto o = overlapping(a, b);
	std::cout << "collision: " << (o ? "true" : "false") << "\n";

	auto n = vec::normalize(a.pos - b.pos);
	std::cout << "normalized: " << n << "\n";
}

int main() {
	rect t1(0.0f, 0.0f, 10.0f, 10.0f);
	rect t2(11.0f, 0.0f, 10.0f, 10.0f);
	rect t3(9.0f, 9.0f, 10.0f, 10.0f);
	collision(t1, t1);
	collision(t1, t2);
	collision(t1, t3);
}