/***********************************************************************
    created:    Wed, 8th Feb 2012
    author:     Lukas E Meindl (based on code by Paul D Turner)
*************************************************************************/
/***************************************************************************
     Copyright (C) 2004 - 2012 Paul D Turner & The CEGUI Development Team

     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.

     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 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.
 ***************************************************************************/
#include "CEGUI/RendererModules/OpenGL/RenderTarget.h"
#include "CEGUI/RenderQueue.h"
#include "CEGUI/RendererModules/OpenGL/GeometryBufferBase.h"
#include "CEGUI/RendererModules/OpenGL/GlmPimpl.h"

#include <cmath>

#include "glm/glm.hpp"
#include "glm/gtc/matrix_transform.hpp"

// Start of CEGUI namespace section
namespace CEGUI
{
//----------------------------------------------------------------------------//
  template <typename T>
  const double OpenGLRenderTarget<T>::d_yfov_tan = 0.267949192431123;

//----------------------------------------------------------------------------//
  template <typename T>
  OpenGLRenderTarget<T>::OpenGLRenderTarget(OpenGLRendererBase &owner) :
    d_owner(owner),
    d_area(0, 0, 0, 0),
    d_matrix(0),
    d_matrixValid(false),
    d_viewDistance(0)
  {
    d_matrix = new mat4Pimpl();
  }

//----------------------------------------------------------------------------//
  template <typename T>
  OpenGLRenderTarget<T>::~OpenGLRenderTarget()
  {
    delete d_matrix;
  }

//----------------------------------------------------------------------------//
  template <typename T>
  void OpenGLRenderTarget<T>::draw(const GeometryBuffer &buffer)
  {
    buffer.draw();
  }

//----------------------------------------------------------------------------//
  template <typename T>
  void OpenGLRenderTarget<T>::draw(const RenderQueue &queue)
  {
    queue.draw();
  }

//----------------------------------------------------------------------------//
  template <typename T>
  void OpenGLRenderTarget<T>::setArea(const Rectf &area)
  {
    d_area = area;
    d_matrixValid = false;

    RenderTargetEventArgs args(this);
    T::fireEvent(RenderTarget::EventAreaChanged, args);
  }

//----------------------------------------------------------------------------//
  template <typename T>
  const Rectf &OpenGLRenderTarget<T>::getArea() const
  {
    return d_area;
  }

//----------------------------------------------------------------------------//
  template <typename T>
  void OpenGLRenderTarget<T>::activate()
  {
    gl::glViewport(static_cast<gl::GLsizei>(d_area.left()),
      static_cast<gl::GLsizei>(d_area.top()),
      static_cast<gl::GLsizei>(d_area.getWidth()),
      static_cast<gl::GLsizei>(d_area.getHeight()));

    if (!d_matrixValid)
    { updateMatrix(); }

    d_owner.setViewProjectionMatrix(d_matrix);

    d_owner.setActiveRenderTarget(this);
  }

//----------------------------------------------------------------------------//
  template <typename T>
  void OpenGLRenderTarget<T>::deactivate()
  {
  }

//----------------------------------------------------------------------------//
  template <typename T>
  void OpenGLRenderTarget<T>::unprojectPoint(const GeometryBuffer &buff,
    const Vector2f &p_in, Vector2f &p_out) const
  {
    if (!d_matrixValid)
    { updateMatrix(); }

    const OpenGLGeometryBufferBase &gb =
      static_cast<const OpenGLGeometryBufferBase &>(buff);

    const gl::GLint vp[4] =
    {
      static_cast<gl::GLint>(d_area.left()),
      static_cast<gl::GLint>(d_area.top()),
      static_cast<gl::GLint>(d_area.getWidth()),
      static_cast<gl::GLint>(d_area.getHeight())
    };

    gl::GLdouble in_x = 0.0, in_y = 0.0, in_z = 0.0;

    glm::ivec4 viewPort = glm::ivec4(vp[0], vp[1], vp[2], vp[3]);
    const glm::mat4 &projMatrix = d_matrix->d_matrix;
    const glm::mat4 &modelMatrix = gb.getMatrix()->d_matrix;

    // unproject the ends of the ray
    glm::vec3 unprojected1;
    glm::vec3 unprojected2;
    in_x = vp[2] * 0.5;
    in_y = vp[3] * 0.5;
    in_z = -d_viewDistance;
    unprojected1 =  glm::unProject(glm::vec3(in_x, in_y, in_z), modelMatrix, projMatrix, viewPort);
    in_x = p_in.d_x;
    in_y = vp[3] - p_in.d_y;
    in_z = 0.0;
    unprojected2 = glm::unProject(glm::vec3(in_x, in_y, in_z), modelMatrix, projMatrix, viewPort);

    // project points to orientate them with GeometryBuffer plane
    glm::vec3 projected1;
    glm::vec3 projected2;
    glm::vec3 projected3;
    in_x = 0.0;
    in_y = 0.0;
    projected1 = glm::project(glm::vec3(in_x, in_y, in_z), modelMatrix, projMatrix, viewPort);
    in_x = 1.0;
    in_y = 0.0;
    projected2 = glm::project(glm::vec3(in_x, in_y, in_z), modelMatrix, projMatrix, viewPort);
    in_x = 0.0;
    in_y = 1.0;
    projected3 = glm::project(glm::vec3(in_x, in_y, in_z), modelMatrix, projMatrix, viewPort);

    // calculate vectors for generating the plane
    const glm::vec3 pv1 = projected2 - projected1;
    const glm::vec3 pv2 = projected3 - projected1;
    // given the vectors, calculate the plane normal
    const glm::vec3 planeNormal = glm::cross(pv1, pv2);
    // calculate plane
    const glm::vec3 planeNormalNormalized = glm::normalize(planeNormal);
    const double pl_d = - glm::dot(projected1, planeNormalNormalized);
    // calculate vector of picking ray
    const glm::vec3 rv = unprojected1 - unprojected2;
    // calculate intersection of ray and plane
    const double pn_dot_r1 = glm::dot(unprojected1, planeNormal);
    const double pn_dot_rv = glm::dot(rv, planeNormal);
    const double tmp1 = pn_dot_rv != 0.0 ? (pn_dot_r1 + pl_d) / pn_dot_rv : 0.0;
    const double is_x = unprojected1.x - rv.x * tmp1;
    const double is_y = unprojected1.y - rv.y * tmp1;

    p_out.d_x = static_cast<float>(is_x);
    p_out.d_y = static_cast<float>(is_y);

    p_out = p_in; // CrazyEddie wanted this
  }

//----------------------------------------------------------------------------//
  template <typename T>
  void OpenGLRenderTarget<T>::updateMatrix() const
  {
    const float w = d_area.getWidth();
    const float h = d_area.getHeight();

    // We need to check if width or height are zero and act accordingly to prevent running into issues
    // with divisions by zero which would lead to undefined values, as well as faulty clipping planes
    // This is mostly important for avoiding asserts
    const bool widthAndHeightNotZero = ( w != 0.0f ) && ( h != 0.0f);

    const float aspect = widthAndHeightNotZero ? w / h : 1.0f;
    const float midx = widthAndHeightNotZero ? w * 0.5f : 0.5f;
    const float midy = widthAndHeightNotZero ? h * 0.5f : 0.5f;
    d_viewDistance = midx / (aspect * d_yfov_tan);

    glm::vec3 eye = glm::vec3(midx, midy, float(-d_viewDistance));
    glm::vec3 center = glm::vec3(midx, midy, 1);
    glm::vec3 up = glm::vec3(0, -1, 0);

    //Older glm versions use degrees as parameter here by default (Unless radians are forced via GLM_FORCE_RADIANS). Newer versions of glm exlusively use radians.
#if (GLM_VERSION_MAJOR == 0 && GLM_VERSION_MINOR <= 9 && GLM_VERSION_PATCH < 6) && (!defined(GLM_FORCE_RADIANS))
    glm::mat4 projectionMatrix = glm::perspective(30.f, aspect, float(d_viewDistance * 0.5), float(d_viewDistance * 2.0));
#else
    glm::mat4 projectionMatrix = glm::perspective(glm::radians(30.f), aspect, float(d_viewDistance * 0.5), float(d_viewDistance * 2.0));
#endif

    // Projection matrix abuse!
    glm::mat4 viewMatrix = glm::lookAt(eye, center, up);

    d_matrix->d_matrix = projectionMatrix * viewMatrix;

    d_matrixValid = true;
  }

//----------------------------------------------------------------------------//

} // End of  CEGUI namespace section
