source/3d/tracktype.cpp

   1 /* $Id$
   2
   3 This file is part of R²C²
   4 Copyright © 2010-2011  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::Vector &p1, const R2C2::Vector &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::Vector 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 Vector &ballast_min = ballast_profile.get_min_coords();
  84         const Vector &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 Vector &rail_min = rail_profile.get_min_coords();
  89         const Vector &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                 const GL::Mesh *m = object->get_mesh();
  99                 const GL::VertexArray &vertices = m->get_vertices();
 100                 int vertex_offs = vertices.get_format().offset(GL::VERTEX2);
 101                 if(vertex_offs>=0)
 102                 {
 103                         for(unsigned i=0; i<vertices.size(); ++i)
 104                         {
 105                                 const float *v = vertices[i]+vertex_offs;
 106                                 border.push_back(Vector(v[0], v[1]));
 107                         }
 108                 }
 109         }
 110         else
 111         {
 112                 mesh = new GL::Mesh((GL::NORMAL3, GL::TEXCOORD2, GL::VERTEX3));
 113                 mesh->set_winding(&GL::WindingTest::counterclockwise());
 114                 GL::MeshBuilder bld(*mesh);
 115
 116                 unsigned index = 0;
 117                 bld.texcoord(0.25, 0.5);
 118                 for(vector<TrackPart>::const_iterator i=parts.begin(); i!=parts.end(); ++i)
 119                         build_part(*i, ballast_profile, Vector(0, -ballast_min.y), false, bld, index);
 120
 121                 bld.texcoord(0.75, 0.5);
 122                 float y = ballast_h-rail_min.y;
 123                 for(vector<TrackPart>::const_iterator i=parts.begin(); i!=parts.end(); ++i)
 124                         build_part(*i, rail_profile, Vector(-gauge/2, y), true, bld, index);
 125                 for(vector<TrackPart>::const_iterator i=parts.begin(); i!=parts.end(); ++i)
 126                         build_part(*i, rail_profile, Vector(gauge/2, y), false, bld, index);
 127
 128                 object = new GL::Object;
 129                 object->set_mesh(mesh);
 130                 object->set_technique(catalogue.get<GL::Technique>(cat.get_track_technique()));
 131         }
 132
 133         unsigned paths = tt.get_paths();
 134         for(unsigned i=0; paths; ++i, paths>>=1)
 135         {
 136                 GL::Mesh *m = 0;
 137                 if(paths&1)
 138                 {
 139                         m = new GL::Mesh(GL::VERTEX3);
 140                         GL::MeshBuilder bld(*m);
 141                         unsigned index = 0;
 142                         for(vector<TrackPart>::const_iterator j=parts.begin(); j!=parts.end(); ++j)
 143                                 if(j->get_path()==i)
 144                                         build_part(*j, cat.get_path_profile(), Vector(0, ballast_h+1.5*rail_h), false, bld, index);
 145                 }
 146                 path_meshes.push_back(m);
 147         }
 148
 149         min_z = max_z = border.front().z;
 150         for(vector<Vector>::iterator i=border.begin(); i!=border.end(); ++i)
 151         {
 152                 min_z = min(min_z, i->z);
 153                 max_z = max(max_z, i->z);
 154         }
 155         border.erase(graham_scan(border.begin(), border.end()), border.end());
 156 }
 157
 158 TrackType3D::~TrackType3D()
 159 {
 160         for(vector<GL::Mesh *>::iterator i=path_meshes.begin(); i!=path_meshes.end(); ++i)
 161                 delete *i;
 162 }
 163
 164 void TrackType3D::get_bounds(float angle, Vector &minp, Vector &maxp) const
 165 {
 166         float c = cos(-angle);
 167         float s = sin(-angle);
 168
 169         minp = maxp = Vector();
 170         minp.z = min_z;
 171         maxp.z = max_z;
 172
 173         for(vector<Vector>::const_iterator i=border.begin(); i!=border.end(); ++i)
 174         {
 175                 float x = c*i->x-s*i->y;
 176                 float y = s*i->x+c*i->y;
 177
 178                 minp.x = min(minp.x, x);
 179                 minp.y = min(minp.y, y);
 180                 maxp.x = max(maxp.x, x);
 181                 maxp.y = max(maxp.y, y);
 182         }
 183 }
 184
 185 const GL::Mesh &TrackType3D::get_path_mesh(unsigned p) const
 186 {
 187         if(p>=path_meshes.size() || !path_meshes[p])
 188                 throw InvalidParameterValue("Invalid path");
 189         return *path_meshes[p];
 190 }
 191
 192 void TrackType3D::build_part(const TrackPart &part, const Profile &profile, const Vector &offset, bool mirror, GL::MeshBuilder &bld, unsigned &base_index)
 193 {
 194         float plen = part.get_length();
 195         unsigned nsegs = (part.is_curved() ? static_cast<unsigned>(plen*32)+1 : 1);
 196
 197         unsigned n_vertices = profile.get_n_vertices();
 198         for(unsigned i=0; i<=nsegs; ++i)
 199         {
 200                 TrackPoint basep = part.get_point(i*plen/nsegs);
 201                 float c = cos(basep.dir);
 202                 float s = sin(basep.dir);
 203
 204                 for(unsigned j=0; j<n_vertices; ++j)
 205                 {
 206                         const Profile::Vertex &v = profile.get_vertex(mirror ? n_vertices-1-j : j);
 207                         Vector p = v.pos;
 208                         if(mirror)
 209                                 p.x = -p.x;
 210                         p.z = basep.pos.z+p.y+offset.y;
 211                         p.y = basep.pos.y-c*(p.x+offset.x);
 212                         p.x = basep.pos.x+s*(p.x+offset.x);
 213
 214                         Vector n = v.normal;
 215                         if(mirror)
 216                                 n.x = -n.x;
 217
 218                         bld.normal(s*n.x, -c*n.x, n.y);
 219                         bld.vertex(p.x, p.y, p.z);
 220
 221                         border.push_back(p);
 222                 }
 223         }
 224
 225         for(unsigned i=0; i+1<n_vertices; )
 226         {
 227                 bld.begin(GL::TRIANGLE_STRIP);
 228                 for(unsigned j=0; j<=nsegs; ++j)
 229                 {
 230                         unsigned k = j*n_vertices+i;
 231                         bld.element(base_index+k+1);
 232                         bld.element(base_index+k);
 233                 }
 234                 bld.end();
 235
 236                 ++i;
 237                 if(!profile.get_vertex(i).smooth)
 238                         ++i;
 239         }
 240
 241         base_index += (nsegs+1)*n_vertices;
 242 }
 243
 244 } // namespace R2C2