gecko-dev/gfx/2d/Quaternion.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef MOZILLA_GFX_QUATERNION_H_
#define MOZILLA_GFX_QUATERNION_H_

#include "Types.h"
#include <math.h>
#include <ostream>
#include "mozilla/Attributes.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/gfx/MatrixFwd.h"
#include "mozilla/gfx/Point.h"

namespace mozilla {
namespace gfx {

class Quaternion {
 public:
  Quaternion() : x(0.0f), y(0.0f), z(0.0f), w(1.0f) {}

  Quaternion(Float aX, Float aY, Float aZ, Float aW)
      : x(aX), y(aY), z(aZ), w(aW) {}

  Quaternion(const Quaternion& aOther) { memcpy(this, &aOther, sizeof(*this)); }

  Float x, y, z, w;

  friend std::ostream& operator<<(std::ostream& aStream,
                                  const Quaternion& aQuat);

  void Set(Float aX, Float aY, Float aZ, Float aW) {
    x = aX;
    y = aY;
    z = aZ;
    w = aW;
  }

  // Assumes upper 3x3 of aMatrix is a pure rotation matrix (no scaling)
  void SetFromRotationMatrix(const Matrix4x4& aMatrix);

  // result = this * aQuat
  Quaternion operator*(const Quaternion& aQuat) const {
    Quaternion o;
    const Float bx = aQuat.x, by = aQuat.y, bz = aQuat.z, bw = aQuat.w;

    o.x = x * bw + w * bx + y * bz - z * by;
    o.y = y * bw + w * by + z * bx - x * bz;
    o.z = z * bw + w * bz + x * by - y * bx;
    o.w = w * bw - x * bx - y * by - z * bz;
    return o;
  }

  Quaternion& operator*=(const Quaternion& aQuat) {
    *this = *this * aQuat;
    return *this;
  }

  Float Length() const { return sqrt(x * x + y * y + z * z + w * w); }

  Quaternion& Conjugate() {
    x *= -1.f;
    y *= -1.f;
    z *= -1.f;
    return *this;
  }

  Quaternion& Normalize() {
    Float l = Length();
    if (l) {
      l = 1.0f / l;
      x *= l;
      y *= l;
      z *= l;
      w *= l;
    } else {
      x = y = z = 0.f;
      w = 1.f;
    }
    return *this;
  }

  Quaternion& Invert() { return Conjugate().Normalize(); }

  Point3D RotatePoint(const Point3D& aPoint) {
    Float uvx = Float(2.0) * (y * aPoint.z - z * aPoint.y);
    Float uvy = Float(2.0) * (z * aPoint.x - x * aPoint.z);
    Float uvz = Float(2.0) * (x * aPoint.y - y * aPoint.x);

    return Point3D(aPoint.x + w * uvx + y * uvz - z * uvy,
                   aPoint.y + w * uvy + z * uvx - x * uvz,
                   aPoint.z + w * uvz + x * uvy - y * uvx);
  }
};

}  // namespace gfx
}  // namespace mozilla

#endif