hydra/include/matrix2.h

//
//  Matrix2.h
//  Kraken Engine / Hydra
//
//  Copyright 2022 Kearwood Gilbert. All rights reserved.
//
//  Redistribution and use in source and binary forms, with or without modification, are
//  permitted provided that the following conditions are met:
//
//  1. Redistributions of source code must retain the above copyright notice, this list of
//  conditions and the following disclaimer.
//
//  2. Redistributions in binary form must reproduce the above copyright notice, this list
//  of conditions and the following disclaimer in the documentation and/or other materials
//  provided with the distribution.
//
//  THIS SOFTWARE IS PROVIDED BY KEARWOOD GILBERT ''AS IS'' AND ANY EXPRESS OR IMPLIED
//  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
//  FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL KEARWOOD GILBERT OR
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//

#include "vector2.h"

#pragma once

namespace hydra {

class Matrix2
{
public:

  union
  {
    struct
    {
      Vector2 axis_x, axis_y;
    };
    // Matrix components, in column-major order
    float c[4];
  };

  // Default initializer - Creates an identity matrix
  void init();

  void init(float* pMat);

  void init(const Vector2& new_axis_x, const Vector2& new_axis_y);

  void init(const Matrix2& m);

  // Overload comparison operator
  bool operator==(const Matrix2& m) const;

  // Overload compound multiply operator
  Matrix2& operator*=(const Matrix2& m);

  float& operator[](unsigned i);
  float operator[](unsigned i) const;

  // Overload multiply operator
  //Matrix4& operator*(const Matrix4 &m);
  Matrix2 operator*(const Matrix2& m) const;

  float* getPointer();

  void scale(float x, float y);
  void scale(const Vector2& v);
  void scale(float s);
  void rotate(float angle);
  bool invert();
  void transpose();

  static Matrix2 Invert(const Matrix2& m);
  static Matrix2 Transpose(const Matrix2& m);
  static Vector2 Dot(const Matrix2& m, const Vector2& v);

  static Matrix2 Rotation(float);
  static Matrix2 Scaling(const Vector2& v);
  static Matrix2 Identity();
};
static_assert(std::is_pod<Matrix2>::value, "hydra::Matrix2 must be a POD type.");

} // namespace hydra

namespace std {
template<>
struct hash<hydra::Matrix2>
{
public:
  size_t operator()(const hydra::Matrix2& s) const
  {
    size_t h1 = hash<hydra::Vector2>()(s.axis_x);
    size_t h2 = hash<hydra::Vector2>()(s.axis_y);
    return h1 ^ (h2 << 1);
  }
};
} // namespace std