vrvOsgUtils.h

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/******************************************************************************
** Copyright (c) 2014 MAK Technologies, Inc.
** All rights reserved.
******************************************************************************/


#pragma once

#include <osg/Quat>

namespace makVrv
{
   static void makeRotate( osg::Quat& q, const double& angle, const double& x, const double& y, const double& z )
   {
      double coshalfangle = cos( 0.5*angle );
      double sinhalfangle = sin( 0.5*angle );

      q.set(
         x * sinhalfangle,
         y * sinhalfangle,
         z * sinhalfangle,
         coshalfangle);
   }

   static void quatMult( osg::Quat& lhs, const osg::Quat& rhs )
   {
      // Algorithm from:
      // http://www.euclideanspace.com/maths/algebra/realNormedAlgebra/quaternions/code/
      double x =  lhs[0] * rhs[3] + lhs[1] * rhs[2] - lhs[2] * rhs[1] + lhs[3] * rhs[0];
      double y = -lhs[0] * rhs[2] + lhs[1] * rhs[3] + lhs[2] * rhs[0] + lhs[3] * rhs[1];
      double z =  lhs[0] * rhs[1] - lhs[1] * rhs[0] + lhs[2] * rhs[3] + lhs[3] * rhs[2];
      double w = -lhs[0] * rhs[0] - lhs[1] * rhs[1] - lhs[2] * rhs[2] + lhs[3] * rhs[3];

      lhs[0] = x;
      lhs[1] = y;
      lhs[2] = z;
      lhs[3] = w;
   }
}