source/3d/tracktype.cpp

   1 /* $Id$
   2
   3 This file is part of the MSP Märklin suite
   4 Copyright © 2010 Mikkosoft Productions, Mikko Rasa
   5 Distributed under the GPL
   6 */
   7
   8 #include <algorithm>
   9 #include <cmath>
  10 #include <msp/gl/meshbuilder.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 Marklin::Point &p1, const Marklin::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         Marklin::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 Marklin {
  73
  74 TrackType3D::TrackType3D(const Catalogue3D &cat3d, const TrackType &tt):
  75         ballast_mesh((GL::NORMAL3, GL::COLOR4_UBYTE, GL::VERTEX3)),
  76         rail_mesh((GL::NORMAL3, GL::COLOR4_UBYTE, GL::VERTEX3))
  77 {
  78         const Catalogue &cat = cat3d.get_catalogue();
  79         const vector<TrackPart> &parts = tt.get_parts();
  80
  81         const Profile &ballast_profile = cat.get_ballast_profile();
  82         const Point &ballast_min = ballast_profile.get_min_coords();
  83         const Point &ballast_max = ballast_profile.get_max_coords();
  84
  85         const Profile &rail_profile = cat.get_rail_profile();
  86         const Point &rail_min = rail_profile.get_min_coords();
  87         const Point &rail_max = rail_profile.get_max_coords();
  88
  89         float gauge = cat.get_gauge();
  90
  91         {
  92                 unsigned index = 0;
  93                 GL::MeshBuilder bld(ballast_mesh);
  94                 bld.color(0.25f, 0.25f, 0.25f);
  95                 for(vector<TrackPart>::const_iterator i=parts.begin(); i!=parts.end(); ++i)
  96                         build_part(*i, ballast_profile, Point(0, -ballast_min.y), bld, index);
  97         }
  98
  99         {
 100                 unsigned index = 0;
 101                 GL::MeshBuilder bld(rail_mesh);
 102                 bld.color(0.85f, 0.85f, 0.85f);
 103                 float y = ballast_max.y-ballast_min.y-rail_min.y;
 104                 for(vector<TrackPart>::const_iterator i=parts.begin(); i!=parts.end(); ++i)
 105                         build_part(*i, rail_profile, Point(-gauge/2-rail_max.x, y), bld, index);
 106                 for(vector<TrackPart>::const_iterator i=parts.begin(); i!=parts.end(); ++i)
 107                         build_part(*i, rail_profile, Point(gauge/2-rail_min.x, y), bld, index);
 108         }
 109
 110         min_z = max_z = border.front().z;
 111         for(vector<Point>::iterator i=border.begin(); i!=border.end(); ++i)
 112         {
 113                 min_z = min(min_z, i->z);
 114                 max_z = max(max_z, i->z);
 115         }
 116         border.erase(graham_scan(border.begin(), border.end()), border.end());
 117 }
 118
 119 void TrackType3D::get_bounds(float angle, Point &minp, Point &maxp) const
 120 {
 121         float c = cos(-angle);
 122         float s = sin(-angle);
 123
 124         minp = maxp = Point();
 125         minp.z = min_z;
 126         maxp.z = max_z;
 127
 128         for(vector<Point>::const_iterator i=border.begin(); i!=border.end(); ++i)
 129         {
 130                 float x = c*i->x-s*i->y;
 131                 float y = s*i->x+c*i->y;
 132
 133                 minp.x = min(minp.x, x);
 134                 minp.y = min(minp.y, y);
 135                 maxp.x = max(maxp.x, x);
 136                 maxp.y = max(maxp.y, y);
 137         }
 138 }
 139
 140 void TrackType3D::render() const
 141 {
 142         ballast_mesh.draw();
 143         rail_mesh.draw();
 144 }
 145
 146 void TrackType3D::build_part(const TrackPart &part, const Profile &profile, const Point &offset, GL::MeshBuilder &bld, unsigned &base_index)
 147 {
 148         unsigned nsegs = (part.radius ? static_cast<unsigned>(part.length*16)+1 : 1);
 149         float plen = part.length;
 150         if(part.radius)
 151                 plen *= abs(part.radius);
 152
 153         unsigned n_points = profile.get_n_points();
 154         for(unsigned i=0; i<=nsegs; ++i)
 155         {
 156                 float a = part.dir+(part.radius ? i*plen/nsegs/part.radius : 0);
 157                 float c = cos(a);
 158                 float s = sin(a);
 159                 Point basep = part.get_point(i*plen/nsegs);
 160
 161                 Point p;
 162                 for(unsigned j=0; j<n_points; ++j)
 163                 {
 164                         // TODO: smoothing - only duplicate vertex if the angle is large enough
 165
 166                         p = profile.get_point(j);
 167                         p.z = basep.z+p.y+offset.y;
 168                         p.y = basep.y-c*(p.x+offset.x);
 169                         p.x = basep.x+s*(p.x+offset.x);
 170                         if(j>0)
 171                                 bld.vertex(p.x, p.y, p.z);
 172
 173                         if(j+1<n_points)
 174                         {
 175                                 Point n = profile.get_edge_normal(j);
 176                                 bld.normal(s*n.x, -c*n.x, n.y);
 177                                 bld.vertex(p.x, p.y, p.z);
 178                         }
 179
 180                         border.push_back(p);
 181                 }
 182         }
 183
 184         for(unsigned i=0; i+1<n_points; ++i)
 185         {
 186                 bld.begin(GL::TRIANGLE_STRIP);
 187                 for(unsigned j=0; j<=nsegs; ++j)
 188                 {
 189                         unsigned k = (j*(n_points-1)+i)*2;
 190                         bld.element(base_index+k+1);
 191                         bld.element(base_index+k);
 192                 }
 193                 bld.end();
 194         }
 195
 196         base_index += (nsegs+1)*(n_points-1)*2;
 197 }
 198
 199 } // namespace Marklin