source/cylinder.cpp

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