source/cylinder.cpp

   1 #include <cmath>
   2 #include "cylinder.h"
   3 #include "primitivebuilder.h"
   4
   5 using namespace std;
   6
   7 namespace Msp {
   8 namespace GL {
   9
  10 CylinderBuilder::CylinderBuilder(float r, float l, unsigned s):
  11         radius(r),
  12         length(l),
  13         segments(s)
  14 {
  15         if(segments<3)
  16                 segments = 3;
  17 }
  18
  19 void CylinderBuilder::build(PrimitiveBuilder &builder) const
  20 {
  21         if(generate_tbn)
  22                 builder.binormal(0, 1, 0);
  23         for(unsigned i=0; i<2; ++i)
  24         {
  25                 float z = (i-0.5)*length;
  26                 builder.normal(0, 0, i*2.0-1.0);
  27                 builder.texcoord(0.5, 0.5);
  28                 if(generate_tbn)
  29                         builder.tangent((i ? 1 : -1), 0, 0);
  30                 builder.vertex(0, 0, z);
  31                 for(unsigned j=0; j<segments; ++j)
  32                 {
  33                         float a = j*M_PI*2/segments;
  34                         float c = cos(a);
  35                         float s = sin(a);
  36                         builder.texcoord(0.5+(i ? 0.5 : -0.5)*c, 0.5+0.5*s);
  37                         builder.vertex(radius*c, radius*s, z);
  38                 }
  39         }
  40
  41         float u_scale = 1.0/segments;
  42         float v_scale = 1;
  43         adjust_texture_scale(u_scale, v_scale, radius*M_PI*2, length);
  44
  45         if(generate_tbn)
  46                 builder.binormal(0, 0, 1);
  47         for(unsigned i=0; i<2; ++i)
  48         {
  49                 float z = (i-0.5)*length;
  50                 for(unsigned j=0; j<=segments; ++j)
  51                 {
  52                         float a = j*M_PI*2/segments;
  53                         float c = cos(a);
  54                         float s = sin(a);
  55                         builder.normal(c, s, 0);
  56                         builder.texcoord(j*u_scale, i*v_scale);
  57                         if(generate_tbn)
  58                                 builder.tangent(-s, c, 0);
  59                         builder.vertex(radius*c, radius*s, z);
  60                 }
  61         }
  62
  63         unsigned base = 0;
  64         for(unsigned i=0; i<2; ++i)
  65         {
  66                 builder.begin(TRIANGLE_FAN);
  67                 builder.element(base);
  68                 for(unsigned j=0; j<=segments; ++j)
  69                         builder.element(base+1+j%segments);
  70                 builder.end();
  71
  72                 base += segments+1;
  73         }
  74
  75         builder.begin(TRIANGLE_STRIP);
  76         for(unsigned j=0; j<=segments; ++j)
  77         {
  78                 builder.element(base+segments+1+j);
  79                 builder.element(base+j);
  80         }
  81         builder.end();
  82 }
  83
  84 } // namespace GL
  85 } // namespace Msp