source/3d/tracktype.cpp

   1 /* $Id$
   2
   3 This file is part of R²C²
   4 Copyright © 2010 Mikkosoft Productions, Mikko Rasa
   5 Distributed under the GPL
   6 */
   7
   8 #include <algorithm>
   9 #include <cmath>
  10 #include <msp/gl/technique.h>
  11 #include "catalogue.h"
  12 #include "tracktype.h"
  13
  14 using namespace std;
  15 using namespace Msp;
  16
  17 namespace {
  18
  19 bool compare_z(const R2C2::Point &p1, const R2C2::Point &p2)
  20 {
  21         return p1.z<p2.z;
  22 }
  23
  24 template<typename Iter>
  25 Iter graham_scan(Iter begin, Iter end)
  26 {
  27         // http://en.wikipedia.org/wiki/Graham_scan
  28
  29         // Find point with lowest X coordinate
  30         R2C2::Point lowest = *begin;
  31         for(Iter i=begin; i!=end; ++i)
  32                 if(i->x<lowest.x || (i->x==lowest.x && i->y>lowest.y))
  33                         lowest = *i;
  34
  35         // Compute tangents and sort points
  36         for(Iter i=begin; i!=end; ++i)
  37                 i->z = (i->x==lowest.x ? 1e5/(i->y-lowest.y-1) : (i->y-lowest.y)/(i->x-lowest.x));
  38         sort(begin, end, compare_z);
  39
  40         for(Iter k=begin, i=k++, j=k++;; )
  41         {
  42                 // Compute winding by cross product
  43                 float turn = (j->x-i->x)*(k->y-j->y) - (k->x-j->x)*(j->y-i->y);
  44
  45                 if(turn<1e-5)
  46                 {
  47                         // Right turn - throw the middle point away
  48                         // Special case for collinear vertices in the beginning
  49                         if(i==begin)
  50                                 j = k++;
  51                         else
  52                                 j = i--;
  53                 }
  54                 else
  55                 {
  56                         // Left turn - store the middle point and advance
  57                         if(++i!=j)
  58                                 *i = *j;
  59                         j = k++;
  60                 }
  61
  62                 // Cycle back to beginning and terminate after checking the last point
  63                 if(k==end)
  64                         k = begin;
  65                 else if(j==begin)
  66                         return ++i;
  67         }
  68 }
  69
  70 }
  71
  72 namespace R2C2 {
  73
  74 TrackType3D::TrackType3D(Catalogue3D &cat3d, const TrackType &tt):
  75         catalogue(cat3d),
  76         mesh(0),
  77         object(0)
  78 {
  79         const Catalogue &cat = cat3d.get_catalogue();
  80         const vector<TrackPart> &parts = tt.get_parts();
  81
  82         const Profile &ballast_profile = cat.get_ballast_profile();
  83         const Point &ballast_min = ballast_profile.get_min_coords();
  84         const Point &ballast_max = ballast_profile.get_max_coords();
  85         float ballast_h = ballast_max.y-ballast_min.y;
  86
  87         const Profile &rail_profile = cat.get_rail_profile();
  88         const Point &rail_min = rail_profile.get_min_coords();
  89         const Point &rail_max = rail_profile.get_max_coords();
  90         float rail_h = rail_max.y-rail_min.y;
  91
  92         float gauge = cat.get_gauge();
  93
  94         string obj_name = tt.get_object();
  95         if(!obj_name.empty())
  96         {
  97                 object = catalogue.get<GL::Object>(obj_name);
  98                 // XXX border
  99         }
 100         else
 101         {
 102                 mesh = new GL::Mesh((GL::NORMAL3, GL::TEXCOORD2, GL::VERTEX3));
 103                 mesh->set_winding(&GL::WindingTest::counterclockwise());
 104                 GL::MeshBuilder bld(*mesh);
 105
 106                 unsigned index = 0;
 107                 bld.texcoord(0.25, 0.5);
 108                 for(vector<TrackPart>::const_iterator i=parts.begin(); i!=parts.end(); ++i)
 109                         build_part(*i, ballast_profile, Point(0, -ballast_min.y), false, bld, index);
 110
 111                 bld.texcoord(0.75, 0.5);
 112                 float y = ballast_h-rail_min.y;
 113                 for(vector<TrackPart>::const_iterator i=parts.begin(); i!=parts.end(); ++i)
 114                         build_part(*i, rail_profile, Point(-gauge/2, y), true, bld, index);
 115                 for(vector<TrackPart>::const_iterator i=parts.begin(); i!=parts.end(); ++i)
 116                         build_part(*i, rail_profile, Point(gauge/2, y), false, bld, index);
 117
 118                 object = new GL::Object;
 119                 object->set_mesh(mesh);
 120                 object->set_technique(catalogue.get<GL::Technique>(cat.get_track_technique()));
 121         }
 122
 123         unsigned paths = tt.get_paths();
 124         for(unsigned i=0; paths; ++i, paths>>=1)
 125         {
 126                 GL::Mesh *m = 0;
 127                 if(paths&1)
 128                 {
 129                         m = new GL::Mesh(GL::VERTEX3);
 130                         GL::MeshBuilder bld(*m);
 131                         unsigned index = 0;
 132                         for(vector<TrackPart>::const_iterator j=parts.begin(); j!=parts.end(); ++j)
 133                                 if(j->get_path()==i)
 134                                         build_part(*j, cat.get_path_profile(), Point(0, ballast_h+1.5*rail_h), false, bld, index);
 135                 }
 136                 path_meshes.push_back(m);
 137         }
 138
 139         min_z = max_z = border.front().z;
 140         for(vector<Point>::iterator i=border.begin(); i!=border.end(); ++i)
 141         {
 142                 min_z = min(min_z, i->z);
 143                 max_z = max(max_z, i->z);
 144         }
 145         border.erase(graham_scan(border.begin(), border.end()), border.end());
 146 }
 147
 148 TrackType3D::~TrackType3D()
 149 {
 150         for(vector<GL::Mesh *>::iterator i=path_meshes.begin(); i!=path_meshes.end(); ++i)
 151                 delete *i;
 152 }
 153
 154 void TrackType3D::get_bounds(float angle, Point &minp, Point &maxp) const
 155 {
 156         float c = cos(-angle);
 157         float s = sin(-angle);
 158
 159         minp = maxp = Point();
 160         minp.z = min_z;
 161         maxp.z = max_z;
 162
 163         for(vector<Point>::const_iterator i=border.begin(); i!=border.end(); ++i)
 164         {
 165                 float x = c*i->x-s*i->y;
 166                 float y = s*i->x+c*i->y;
 167
 168                 minp.x = min(minp.x, x);
 169                 minp.y = min(minp.y, y);
 170                 maxp.x = max(maxp.x, x);
 171                 maxp.y = max(maxp.y, y);
 172         }
 173 }
 174
 175 const GL::Mesh &TrackType3D::get_path_mesh(unsigned p) const
 176 {
 177         if(p>=path_meshes.size() || !path_meshes[p])
 178                 throw InvalidParameterValue("Invalid path");
 179         return *path_meshes[p];
 180 }
 181
 182 void TrackType3D::build_part(const TrackPart &part, const Profile &profile, const Point &offset, bool mirror, GL::MeshBuilder &bld, unsigned &base_index)
 183 {
 184         float plen = part.get_length();
 185         unsigned nsegs = (part.is_curved() ? static_cast<unsigned>(plen*32)+1 : 1);
 186
 187         unsigned n_vertices = profile.get_n_vertices();
 188         for(unsigned i=0; i<=nsegs; ++i)
 189         {
 190                 TrackPoint basep = part.get_point(i*plen/nsegs);
 191                 float c = cos(basep.dir);
 192                 float s = sin(basep.dir);
 193
 194                 for(unsigned j=0; j<n_vertices; ++j)
 195                 {
 196                         const Profile::Vertex &v = profile.get_vertex(mirror ? n_vertices-1-j : j);
 197                         Point p = v.pos;
 198                         if(mirror)
 199                                 p.x = -p.x;
 200                         p.z = basep.pos.z+p.y+offset.y;
 201                         p.y = basep.pos.y-c*(p.x+offset.x);
 202                         p.x = basep.pos.x+s*(p.x+offset.x);
 203
 204                         Point n = v.normal;
 205                         if(mirror)
 206                                 n.x = -n.x;
 207
 208                         bld.normal(s*n.x, -c*n.x, n.y);
 209                         bld.vertex(p.x, p.y, p.z);
 210
 211                         border.push_back(p);
 212                 }
 213         }
 214
 215         for(unsigned i=0; i+1<n_vertices; )
 216         {
 217                 bld.begin(GL::TRIANGLE_STRIP);
 218                 for(unsigned j=0; j<=nsegs; ++j)
 219                 {
 220                         unsigned k = j*n_vertices+i;
 221                         bld.element(base_index+k+1);
 222                         bld.element(base_index+k);
 223                 }
 224                 bld.end();
 225
 226                 ++i;
 227                 if(!profile.get_vertex(i).smooth)
 228                         ++i;
 229         }
 230
 231         base_index += (nsegs+1)*n_vertices;
 232 }
 233
 234 } // namespace R2C2