vec4.h

//Base code written by Jan Allbeck, Chris Czyzewicz, Cory Boatright, Tiantian Liu, Benedict Brown, and Adam Mally
//University of Pennsylvania

#ifndef VEC4_H
#define VEC4_H

#include <array>
#include <iostream>

class vec4
{
private:
    ///The set of floats representing the coordinates of the vector
    std::array<float, 4> data;

public:
    ///----------------------------------------------------------------------
    /// Constructors
    ///----------------------------------------------------------------------
    // Default constructor. Initializes all elements to 0.
    vec4();
    vec4(float x, float y, float z, float w);
    vec4(const vec4
             &v2); // copy constructor, sets each element of this->data to v2's corresponding data

    ///----------------------------------------------------------------------
    /// Getters/Setters
    ///----------------------------------------------------------------------
    /// Returns the value at index
    float operator[](unsigned int index) const;

    /// Returns a reference to the value at index
    float &operator[](unsigned int index);

    ///----------------------------------------------------------------------
    /// Operator Functions
    ///----------------------------------------------------------------------

    /// Sets each element of this->data to v2's corresponding data, then returns this
    vec4 &operator=(const vec4 &v2);

    /// Test for equality
    bool operator==(const vec4 &v2) const; //Component-wise comparison

    /// Test for inequality
    bool operator!=(const vec4 &v2) const; //Component-wise comparison

    /// Arithmetic:
    /// e.g. += adds v2 to this and return this (like regular +=)
    ///      +  returns a new vector that is sum of this and v2
    vec4 &operator+=(const vec4 &v2);
    vec4 &operator-=(const vec4 &v2);
    vec4 &operator*=(float c); // multiplication by a scalar
    vec4 &operator/=(float c); // division by a scalar

    vec4 operator+(const vec4 &v2) const;
    vec4 operator-(const vec4 &v2) const;
    vec4 operator*(float c) const; // multiplication by a scalar
    vec4 operator/(float c) const; // division by a scalar
};

/// Dot Product
float dot(const vec4 &v1, const vec4 &v2);

/// Cross Product
vec4 cross(const vec4 &v1,
           const vec4 &v2); //Compute the result of v1 x v2 using only their X, Y, and Z elements.
                            //In other words, treat v1 and v2 as 3D vectors, not 4D vectors.
                            //The fourth element of the resultant vector should be 0.

/// Returns the geometric length of the input vector
float length(const vec4 &v);

/// Scalar Multiplication (c * v)
vec4 operator*(float c, const vec4 &v);

vec4 normalize(const vec4 &v);

/// Prints the vector to a stream in a nice format
std::ostream &operator<<(std::ostream &o, const vec4 &v);

#endif /* VEC4_H */