text: ///////////////////////////////////////////////////////////////////////////////////
  /// OpenGL Mathematics (glm.g-truc.net)
  ///
  /// Copyright (c) 2005 - 2014 G-Truc Creation (www.g-truc.net)
  /// Permission is hereby granted, free of charge, to any person obtaining a copy
  /// of this software and associated documentation files (the "Software"), to deal
  /// in the Software without restriction, including without limitation the rights
  /// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  /// copies of the Software, and to permit persons to whom the Software is
  /// furnished to do so, subject to the following conditions:
  /// 
  /// The above copyright notice and this permission notice shall be included in
  /// all copies or substantial portions of the Software.
  /// 
  /// Restrictions:
  ///		By making use of the Software for military purposes, you choose to make
  ///		a Bunny unhappy.
  /// 
  /// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  /// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  /// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  /// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  /// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  /// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  /// THE SOFTWARE.
  ///
  /// @file test/gtx/gtx_quaternion.cpp
  /// @date 2011-05-25 / 2014-11-25
  /// @author Christophe Riccio
  ///////////////////////////////////////////////////////////////////////////////////
  
  #include <glm/gtc/epsilon.hpp>
  #include <glm/gtc/type_ptr.hpp>
  #include <glm/gtc/matrix_transform.hpp>
  #include <glm/gtx/transform.hpp>
  #include <glm/gtx/quaternion.hpp>
  #include <glm/ext.hpp>
  
  int test_quat_fastMix()
  {
  	int Error = 0;
  
  	glm::quat A = glm::angleAxis(0.0f, glm::vec3(0, 0, 1));
  	glm::quat B = glm::angleAxis(glm::pi<float>() * 0.5f, glm::vec3(0, 0, 1));
  	glm::quat C = glm::fastMix(A, B, 0.5f);
  	glm::quat D = glm::angleAxis(glm::pi<float>() * 0.25f, glm::vec3(0, 0, 1));
  
  	Error += glm::epsilonEqual(C.x, D.x, 0.01f) ? 0 : 1;
  	Error += glm::epsilonEqual(C.y, D.y, 0.01f) ? 0 : 1;
  	Error += glm::epsilonEqual(C.z, D.z, 0.01f) ? 0 : 1;
  	Error += glm::epsilonEqual(C.w, D.w, 0.01f) ? 0 : 1;
  
  	return Error;
  }
  
  int test_quat_shortMix()
  {
  	int Error(0);
  
  	glm::quat A = glm::angleAxis(0.0f, glm::vec3(0, 0, 1));
  	glm::quat B = glm::angleAxis(glm::pi<float>() * 0.5f, glm::vec3(0, 0, 1));
  	glm::quat C = glm::shortMix(A, B, 0.5f);
  	glm::quat D = glm::angleAxis(glm::pi<float>() * 0.25f, glm::vec3(0, 0, 1));
  
  	Error += glm::epsilonEqual(C.x, D.x, 0.01f) ? 0 : 1;
  	Error += glm::epsilonEqual(C.y, D.y, 0.01f) ? 0 : 1;
  	Error += glm::epsilonEqual(C.z, D.z, 0.01f) ? 0 : 1;
  	Error += glm::epsilonEqual(C.w, D.w, 0.01f) ? 0 : 1;
  
  	return Error;
  }
  
  int test_orientation()
  {
  	int Error(0);
  
  	{
  		glm::quat q(1.0f, 0.0f, 0.0f, 1.0f);
  		float p = glm::roll(q);
  	}
  
  	{
  		glm::quat q(1.0f, 0.0f, 0.0f, 1.0f);
  		float p = glm::pitch(q);
  	}
  
  	{
  		glm::quat q(1.0f, 0.0f, 0.0f, 1.0f);
  		float p = glm::yaw(q);
  	}
  
  	return Error;
  }
  
  int test_rotation()
  {
  	int Error(0);
  
  	glm::vec3 v(1, 0, 0);
  	glm::vec3 u(0, 1, 0);
  
  	glm::quat Rotation = glm::rotation(v, u);
  
  	float Angle = glm::angle(Rotation);
  
  	Error += glm::abs(Angle - glm::pi<float>() * 0.5f) < glm::epsilon<float>() ? 0 : 1;
  
  	return Error;
  }
  
  int test_log()
  {
  	int Error(0);
  	
  	glm::quat q;
  	glm::quat p = glm::log(q);
  	glm::quat r = glm::exp(p);
  
  	return Error;
  }
  
  int main()
  {
  	int Error(0);
  
  	Error += test_log();
  	Error += test_rotation();
  	Error += test_quat_fastMix();
  	Error += test_quat_shortMix();
  
  	return Error;
  }
  