source/cylinder.cpp

   1 /* $Id$
   2
   3 This file is part of libmspgl
   4 Copyright © 2011  Mikko Rasa, Mikkosoft Productions
   5 Distributed under the LGPL
   6 */
   7
   8 #include <cmath>
   9 #include "cylinder.h"
  10 #include "primitivebuilder.h"
  11
  12 using namespace std;
  13
  14 namespace Msp {
  15 namespace GL {
  16
  17 CylinderBuilder::CylinderBuilder(float r, float l, unsigned s):
  18         radius(r),
  19         length(l),
  20         segments(s)
  21 {
  22         if(segments<3)
  23                 segments = 3;
  24 }
  25
  26 void CylinderBuilder::build(PrimitiveBuilder &builder) const
  27 {
  28         if(binormal_attr>=0)
  29                 builder.attrib(binormal_attr, 0, 1, 0);
  30         for(unsigned i=0; i<2; ++i)
  31         {
  32                 float z = (i-0.5)*length;
  33                 builder.normal(0, 0, i*2.0-1.0);
  34                 builder.texcoord(0.5, 0.5);
  35                 if(tangent_attr>=0)
  36                         builder.attrib(tangent_attr, (i ? 1 : -1), 0, 0);
  37                 builder.vertex(0, 0, z);
  38                 for(unsigned j=0; j<segments; ++j)
  39                 {
  40                         float a = j*M_PI*2/segments;
  41                         float c = cos(a);
  42                         float s = sin(a);
  43                         builder.texcoord(0.5+(i ? 0.5 : -0.5)*c, 0.5+0.5*s);
  44                         builder.vertex(radius*c, radius*s, z);
  45                 }
  46         }
  47
  48         float u_scale = 1.0/segments;
  49         float v_scale = 1;
  50         adjust_texture_scale(u_scale, v_scale, radius*M_PI*2, length);
  51
  52         if(binormal_attr>=0)
  53                 builder.attrib(binormal_attr, 0, 0, 1);
  54         for(unsigned i=0; i<2; ++i)
  55         {
  56                 float z = (i-0.5)*length;
  57                 for(unsigned j=0; j<=segments; ++j)
  58                 {
  59                         float a = j*M_PI*2/segments;
  60                         float c = cos(a);
  61                         float s = sin(a);
  62                         builder.normal(c, s, 0);
  63                         builder.texcoord(j*u_scale, i*v_scale);
  64                         if(tangent_attr>=0)
  65                                 builder.attrib(tangent_attr, -s, c, 0);
  66                         builder.vertex(radius*c, radius*s, z);
  67                 }
  68         }
  69
  70         unsigned base = 0;
  71         for(unsigned i=0; i<2; ++i)
  72         {
  73                 builder.begin(TRIANGLE_FAN);
  74                 builder.element(base);
  75                 for(unsigned j=0; j<=segments; ++j)
  76                         builder.element(base+1+j%segments);
  77                 builder.end();
  78
  79                 base += segments+1;
  80         }
  81
  82         builder.begin(TRIANGLE_STRIP);
  83         for(unsigned j=0; j<=segments; ++j)
  84         {
  85                 builder.element(base+segments+1+j);
  86                 builder.element(base+j);
  87         }
  88         builder.end();
  89 }
  90
  91 } // namespace GL
  92 } // namespace Msp