source/sphere.cpp

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