text: // Filename: orthographicLens.cxx
  // Created by:  mike (18Feb99)
  //
  ////////////////////////////////////////////////////////////////////
  //
  // PANDA 3D SOFTWARE
  // Copyright (c) Carnegie Mellon University.  All rights reserved.
  //
  // All use of this software is subject to the terms of the revised BSD
  // license.  You should have received a copy of this license along
  // with this source code in a file named "LICENSE."
  //
  ////////////////////////////////////////////////////////////////////
  
  #include "orthographicLens.h"
  #include "indent.h"
  #include "bamReader.h"
  
  TypeHandle OrthographicLens::_type_handle;
  
  
  ////////////////////////////////////////////////////////////////////
  //     Function: OrthographicLens::make_copy
  //       Access: Public, Virtual
  //  Description: Allocates a new Lens just like this one.
  ////////////////////////////////////////////////////////////////////
  PT(Lens) OrthographicLens::
  make_copy() const {
    return new OrthographicLens(*this);
  }
  
  ////////////////////////////////////////////////////////////////////
  //     Function: OrthographicLens::is_linear
  //       Access: Published, Virtual
  //  Description: Returns true if the lens represents a linear
  //               projection (e.g. PerspectiveLens, OrthographicLens),
  //               and therefore there is a valid matrix returned by
  //               get_projection_mat(), or false otherwise.
  ////////////////////////////////////////////////////////////////////
  bool OrthographicLens::
  is_linear() const {
    return true;
  }
  
  ////////////////////////////////////////////////////////////////////
  //     Function: OrthographicLens::is_orthographic
  //       Access: Published, Virtual
  //  Description: Returns true if the lens represents a orthographic
  //               projection (i.e. it is a OrthographicLens), false
  //               otherwise.
  ////////////////////////////////////////////////////////////////////
  bool OrthographicLens::
  is_orthographic() const {
    return true;
  }
  
  ////////////////////////////////////////////////////////////////////
  //     Function: OrthographicLens::write
  //       Access: Public, Virtual
  //  Description: 
  ////////////////////////////////////////////////////////////////////
  void OrthographicLens::
  write(ostream &out, int indent_level) const {
    indent(out, indent_level) << get_type() << " film size = " << get_film_size() << "\n";
  }
  
  ////////////////////////////////////////////////////////////////////
  //     Function: OrthographicLens::do_extrude_depth
  //       Access: Protected, Virtual
  //  Description: This is the generic implementation, which is based on
  //               do_extrude() and assumes a linear distribution of
  //               depth values between the near and far points.
  ////////////////////////////////////////////////////////////////////
  bool OrthographicLens::
  do_extrude_depth(const CData *cdata,
                   const LPoint3 &point2d, LPoint3 &point3d) const {
    return do_extrude_depth_with_mat(cdata, point2d, point3d);
  }
  
  ////////////////////////////////////////////////////////////////////
  //     Function: OrthographicLens::do_compute_projection_mat
  //       Access: Protected, Virtual
  //  Description: Computes the complete transformation matrix from 3-d
  //               point to 2-d point, if the lens is linear.
  ////////////////////////////////////////////////////////////////////
  void OrthographicLens::
  do_compute_projection_mat(Lens::CData *lens_cdata) {
    CoordinateSystem cs = lens_cdata->_cs;
    if (cs == CS_default) {
      cs = get_default_coordinate_system();
    }
  
    PN_stdfloat a = 2.0f / (lens_cdata->_far_distance - lens_cdata->_near_distance);
    PN_stdfloat b = -(lens_cdata->_far_distance + lens_cdata->_near_distance) / (lens_cdata->_far_distance - lens_cdata->_near_distance);
  
    LMatrix4 canonical;
    switch (cs) {
    case CS_zup_right:
      canonical.set(1.0f,  0.0f,  0.0f,  0.0f,
                    0.0f,  0.0f,     a,  0.0f,
                    0.0f,  1.0f,  0.0f,  0.0f,
                    0.0f,  0.0f,     b,  1.0f);
      break;
  
    case CS_yup_right:
      canonical.set(1.0f,  0.0f,  0.0f,  0.0f,
                    0.0f,  1.0f,  0.0f,  0.0f,
                    0.0f,  0.0f,    -a,  0.0f,
                    0.0f,  0.0f,     b,  1.0f);
      break;
  
    case CS_zup_left:
      canonical.set(1.0f,  0.0f,  0.0f,  0.0f,
                    0.0f,  0.0f,    -a,  0.0f,
                    0.0f,  1.0f,  0.0f,  0.0f,
                    0.0f,  0.0f,     b,  1.0f);
      break;
  
    case CS_yup_left:
      canonical.set(1.0f,  0.0f,  0.0f,  0.0f,
                    0.0f,  1.0f,  0.0f,  0.0f,
                    0.0f,  0.0f,     a,  0.0f,
                    0.0f,  0.0f,     b,  1.0f);
      break;
  
    default:
      gobj_cat.error()
        << "Invalid coordinate system " << (int)cs << " in OrthographicLens!\n";
      canonical = LMatrix4::ident_mat();
    }
  
    lens_cdata->_projection_mat = do_get_lens_mat_inv(lens_cdata) * canonical * do_get_film_mat(lens_cdata);
    lens_cdata->_projection_mat_left = lens_cdata->_projection_mat_right = lens_cdata->_projection_mat;
  
    do_adjust_comp_flags(lens_cdata, 
                         CF_projection_mat_inv | CF_projection_mat_left_inv | CF_projection_mat_right_inv,
                         CF_projection_mat);
  }
  
  ////////////////////////////////////////////////////////////////////
  //     Function: OrthographicLens::register_with_read_factory
  //       Access: Public, Static
  //  Description: Tells the BamReader how to create objects of type
  //               Lens.
  ////////////////////////////////////////////////////////////////////
  void OrthographicLens::
  register_with_read_factory() {
    BamReader::get_factory()->register_factory(get_class_type(), make_from_bam);
  }
  
  ////////////////////////////////////////////////////////////////////
  //     Function: OrthographicLens::make_from_bam
  //       Access: Protected, Static
  //  Description: This function is called by the BamReader's factory
  //               when a new object of type Lens is encountered
  //               in the Bam file.  It should create the Lens
  //               and extract its information from the file.
  ////////////////////////////////////////////////////////////////////
  TypedWritable *OrthographicLens::
  make_from_bam(const FactoryParams &params) {
    OrthographicLens *lens = new OrthographicLens;
    DatagramIterator scan;
    BamReader *manager;
  
    parse_params(params, scan, manager);
    lens->fillin(scan, manager);
  
    return lens;
  }
  