mpri-graphics-project/common_structures.hpp

/**
 * Defines a few widely used, widely spread structures. Imported pervasively.
 **/

#pragma once

#include <functional>  // Hash
#include <vector>
#include <cassert>
#include <cmath>

struct Point {
    Point(double x, double y, double z) : x(x), y(y), z(z) {}
    double x, y, z;

    double operator[](unsigned i) const {
        assert(i < 3);
        switch(i) {
            case 0:     return x;
            case 1:     return y;
            case 2:     return z;
            default:    return 0;
        }
    }

    bool operator==(const Point& pt) const {
        return fabs(x - pt.x) < 1e-9
            && fabs(y - pt.y) < 1e-9
            && fabs(z - pt.z) < 1e-9;
    }

    Point operator+(const Point& pt) const {
        return Point(
                x + pt.x,
                y + pt.y,
                z + pt.z);
    }
    Point& operator+=(const Point& pt) {
        x += pt.x;
        y += pt.y;
        z += pt.z;
        return *this;
    }

    Point& operator-=(const Point& pt) {
        return (*this += Point(-pt.x, -pt.y, -pt.z));
    }

    Point operator-(const Point& pt) const {
        return (*this) + (-1 * pt);
    }

    friend Point operator*(double scalar, const Point& pt) {
        return Point(
                scalar * pt.x,
                scalar * pt.y,
                scalar * pt.z);
    }

    Point cross_prod(const Point& pt) const {
        return Point(
                (*this)[1] * pt[2] - (*this)[2] * pt[1],
                (*this)[2] * pt[0] - (*this)[0] * pt[2],
                (*this)[0] * pt[1] - (*this)[1] * pt[0]);
    }

    bool operator<(const Point& pt) const {
        /// Lexicographic order on (x, y, z)
        if(x == pt.x) {
            if(y == pt.y)
                return z < pt.z;
            return y < pt.y;
        }
        return x < pt.x;
    }
};

struct PointLoc {
    /// Point location: a point with integer coordinates, used to index Points

    PointLoc(int x, int y, int z): x(x), y(y), z(z) {}

    int x, y, z;

    bool operator<(const PointLoc& pt) const {
        if(x == pt.x) {
            if(y == pt.y)
                return z < pt.z;
            return y < pt.y;
        }
        return x < pt.x;
    }

    bool operator==(const PointLoc& pt) const {
        return x == pt.x && y == pt.y && z == pt.z;
    }

    PointLoc operator+(const PointLoc& pt) const {
        return PointLoc(x + pt.x, y + pt.y, z + pt.z);
    }
};

struct Face {
    Face(int v0, int v1, int v2) {
        vert[0] = v0;
        vert[1] = v1;
        vert[2] = v2;
    }
    int vert[3];
    int operator[](unsigned i) const {
        return vert[i % 3]; // dodge errors
    }
    const Point& pt(int id, const std::vector<Point>& pts) const {
        assert(0 <= id && id < 3);
        return pts[vert[id]];
    }
};

class Cuboid {
    /// A 3D box

    public:
        static Cuboid empty() {
            return Cuboid(Point(0, 0, 0), Point(0, 0, 0));
        }

        Cuboid(Point bd1, Point bd2);
        Cuboid(const Cuboid& oth)
            : lowBound(oth.lowBound), highBound(oth.highBound) {}

        double low(unsigned dim) const; ///< Lower bound for a dimension
        double high(unsigned dim) const; ///< Higher bound for a dimension
        double length(unsigned dim) const;

        double volume() const;
        bool is_empty() const;
    private:
        Point lowBound, highBound;
};

namespace std {
	template<> struct hash<Face>
    {
        typedef Face argument_type;
        typedef std::size_t result_type;
        result_type operator()(argument_type const& s) const noexcept
        {
            result_type const h1 ( std::hash<int>{}(s[0]) );
            result_type const h2 ( std::hash<int>{}(s[1]) );
            result_type const h3 ( std::hash<int>{}(s[2]) );
            return h1 ^ h2 ^ h3;
        }
    };
}