Function vm_ExtractAnglesFromMatrix

vecmat/vector.cpp:680–707

extract angles from a matrix

// extract angles from a matrix
angvec *vm_ExtractAnglesFromMatrix(angvec *a, matrix *m) {
  float sinh, cosh, cosp, sinb, cosb;

  // Deal with straight up or straight down
  if (IS_ZERO(m->fvec.x) && IS_ZERO(m->fvec.z)) {
    a->p = (m->fvec.y > 0) ? 0xc000 : 0x4000;
    a->b = 0.0;
    a->h = FixAtan2(m->rvec.x, -m->rvec.z);
    return a;
  }

  a->h = FixAtan2(m->fvec.z, m->fvec.x);

  sinh = FixSin(a->h);
  cosh = FixCos(a->h);

  if (fabs(sinh) > fabs(cosh)) // sine is larger, so use it
    cosp = (m->fvec.x / sinh);
  else // cosine is larger, so use it
    cosp = (m->fvec.z / cosh);
  a->p = FixAtan2(cosp, -m->fvec.y);

  sinb = (m->rvec.y / cosp);
  cosb = (m->uvec.y / cosp);
  a->b = FixAtan2(cosb, sinb);

  return a;
}

// returns the value of a determinant
float calc_det_value(matrix *det) {