turbomath.h

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/*
 *
 * BSD 3-Clause License
 *
 * Copyright (c) 2017, James Jackson  BYU MAGICC Lab, Provo UT
 * All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
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 *   contributors may be used to endorse or promote products derived from
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#ifndef TURBOMATH_TURBOMATH_H
#define TURBOMATH_TURBOMATH_H

#include <cstdint>

namespace turbomath
{
// float-based wrappers
float cos(float x);
float sin(float x);
float asin(float x);
float atan2(float y, float x);
float atan(float x);
float fsign(float y);

// turbo-speed approximation of (1.0 - pow(pressure/101325.0, 0.1902631)) * 39097.63
// Used for calculating altitude in m from atmospheric pressure in Pa
float alt(float x);

float inv_sqrt(float x);
float fabs(float x);

union float_converter_t
{
  float fvalue;
  int32_t ivalue;
};

class Vector
{
public:
  float x;
  float y;
  float z;

  Vector();
  Vector(float x_, float y_, float z_);

  float norm() const;
  float sqrd_norm() const;
  Vector& normalize();
  Vector normalized() const;

  float dot(const Vector& v) const;
  Vector cross(const Vector& v) const;

  Vector operator*(float s) const;
  Vector operator/(float s) const;
  Vector& operator*=(float s);
  Vector& operator/=(float s);
  Vector operator+(const Vector& v) const;
  Vector operator-(const Vector& v) const;
  Vector& operator+=(const Vector& v);
  Vector& operator-=(const Vector& v);
};

inline Vector operator*(float s, const Vector& v)
{
  return v * s;
}
inline Vector operator/(float s, const Vector& v)
{
  return v / s;
}

class Quaternion
{
public:
  float w;
  float x;
  float y;
  float z;

  Quaternion();
  Quaternion(float w_, float x_, float y_, float z_);
  Quaternion(const Vector& u, const Vector& v);
  Quaternion(float roll, float pitch, float yaw);

  Vector rotate(const Vector& v) const;
  Quaternion& normalize();
  Quaternion inverse() const;
  Quaternion& invert();
  Quaternion& from_two_unit_vectors(const Vector& u, const Vector& v);
  Quaternion& from_RPY(float roll, float pitch, float yaw);
  void get_RPY(float* roll, float* pitch, float* yaw) const;

  Vector operator*(const Vector& v) const;
  Quaternion operator*(const Quaternion& q) const;
  Quaternion& operator*=(const Quaternion& q);
  Vector boxminus(const Quaternion& q) const;
  static Vector log(const Quaternion& q)
  {
    Vector v{q.x, q.y, q.z};
    float norm_v = v.norm();

    Vector out;
    if (norm_v < 1e-8)
    {
      out.x = out.y = out.z = 0.0;
    }
    else
    {
      out = 2.0 * atan2(norm_v, q.w) * v / norm_v;
    }
    return out;
  }

  Vector operator-(const Quaternion& q) const { return boxminus(q); }
};

} // namespace turbomath

#endif // TURBOMATH_TURBOMATH_H