content/browser/vr/vr_transform_util.cc

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/browser/vr/vr_transform_util.h"
   6
   7 #include <math.h>
   8
   9 namespace content {
  10
  11 // Source:
  12 // http://www.euclideanspace.com/maths/geometry/rotations/conversions/matrixToQuaternion/
  13 VRVector4Ptr MatrixToOrientationQuaternion(
  14     const float m0[3], const float m1[3], const float m2[3]) {
  15   VRVector4Ptr out = VRVector4::New();
  16   float trace = m0[0] + m1[1] + m2[2];
  17   float root;
  18   if (trace > 0.0f) {
  19     root = sqrtf(1.0f + trace) * 2.0f;
  20     out->x = (m2[1] - m1[2]) / root;
  21     out->y = (m0[2] - m2[0]) / root;
  22     out->z = (m1[0] - m0[1]) / root;
  23     out->w = 0.25f * root;
  24   } else if ((m0[0] > m1[1]) && (m0[0] > m2[2])) {
  25     root = sqrtf(1.0f + m0[0] - m1[1] - m2[2]) * 2.0f;
  26     out->x = 0.25f * root;
  27     out->y = (m0[1] + m1[0]) / root;
  28     out->z = (m0[2] + m2[0]) / root;
  29     out->w = (m2[1] - m1[2]) / root;
  30   } else if (m1[1] > m2[2]) {
  31     root = sqrtf(1.0f + m1[1] - m0[0] - m2[2]) * 2.0f;
  32     out->x = (m0[1] + m1[0]) / root;
  33     out->y = 0.25f * root;
  34     out->z = (m1[2] + m2[1]) / root;
  35     out->w = (m0[2] - m2[0]) / root;
  36   } else {
  37     root = sqrtf(1.0f + m2[2] - m0[0] - m1[1]) * 2.0f;
  38     out->x = (m0[2] + m2[0]) / root;
  39     out->y = (m1[2] + m2[1]) / root;
  40     out->z = 0.25f * root;
  41     out->w = (m1[0] - m0[1]) / root;
  42   }
  43   return out.Pass();
  44 }
  45
  46 }  // namespace content