source/builders/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         for(unsigned i=0; i<2; ++i)
  23         {
  24                 float z = (i-0.5)*length;
  25                 builder.normal(0, 0, i*2.0-1.0);
  26                 builder.texcoord(0.5, 0.5);
  27                 if(generate_tan)
  28                         builder.tangent((i ? 1 : -1), 0, 0);
  29                 builder.vertex(0, 0, z);
  30                 for(unsigned j=0; j<segments; ++j)
  31                 {
  32                         float a = j*M_PI*2/segments;
  33                         float c = cos(a);
  34                         float s = sin(a);
  35                         builder.texcoord(0.5+(i ? 0.5 : -0.5)*c, 0.5+0.5*s);
  36                         builder.vertex(radius*c, radius*s, z);
  37                 }
  38         }
  39
  40         float u_scale = 1.0/segments;
  41         float v_scale = 1;
  42         adjust_texture_scale(u_scale, v_scale, radius*M_PI*2, length);
  43
  44         for(unsigned i=0; i<2; ++i)
  45         {
  46                 float z = (i-0.5)*length;
  47                 for(unsigned j=0; j<=segments; ++j)
  48                 {
  49                         float a = j*M_PI*2/segments;
  50                         float c = cos(a);
  51                         float s = sin(a);
  52                         builder.normal(c, s, 0);
  53                         builder.texcoord(j*u_scale, i*v_scale);
  54                         if(generate_tan)
  55                                 builder.tangent(-s, c, 0);
  56                         builder.vertex(radius*c, radius*s, z);
  57                 }
  58         }
  59
  60         unsigned base = 0;
  61         for(unsigned i=0; i<2; ++i)
  62         {
  63                 builder.begin(TRIANGLE_FAN);
  64                 builder.element(base);
  65                 for(unsigned j=0; j<=segments; ++j)
  66                         builder.element(base+1+j%segments);
  67                 builder.end();
  68
  69                 base += segments+1;
  70         }
  71
  72         builder.begin(TRIANGLE_STRIP);
  73         for(unsigned j=0; j<=segments; ++j)
  74         {
  75                 builder.element(base+segments+1+j);
  76                 builder.element(base+j);
  77         }
  78         builder.end();
  79 }
  80
  81 } // namespace GL
  82 } // namespace Msp