source/capsule.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 "capsule.h"
  10 #include "primitivebuilder.h"
  11
  12 using namespace std;
  13
  14 namespace Msp {
  15 namespace GL {
  16
  17 CapsuleBuilder::CapsuleBuilder(float r, float l, unsigned s, unsigned n):
  18         radius(r),
  19         length(l),
  20         segments(s),
  21         rings(n)
  22 {
  23         if(segments<3)
  24                 segments = 3;
  25         rings |= 1;
  26         if(rings<3)
  27                 rings = 3;
  28 }
  29
  30 void CapsuleBuilder::build(PrimitiveBuilder &builder) const
  31 {
  32         float u_scale = 1.0/segments;
  33         float v_scale = 1/(length+radius*M_PI);
  34         if(tex_fit!=STRETCH)
  35         {
  36                 float l1 = radius*M_PI*2;
  37                 float l2 = length+radius*M_PI;
  38                 if((l1<l2)==(tex_fit==CUT))
  39                         u_scale *= l1/l2;
  40                 else
  41                         v_scale *= l2/l1;
  42         }
  43
  44         builder.normal(0, 0, -1);
  45         builder.texcoord(0.5, 0);
  46         builder.vertex(0, 0, -length/2+radius);
  47         for(unsigned i=1; i<rings; ++i)
  48         {
  49                 float cz = length*(i>rings/2 ? 0.5 : -0.5);
  50                 float v = (i*radius*M_PI/rings+(i>rings/2 ? length : 0))*v_scale;
  51                 float ra = (i>rings/2 ? i-1 : i)*M_PI/(rings-1);
  52                 float rc = cos(ra);
  53                 float rs = sin(ra);
  54                 for(unsigned j=0; j<=segments; ++j)
  55                 {
  56                         float sa = j*M_PI*2/segments;
  57                         float sc = cos(sa);
  58                         float ss = sin(sa);
  59                         builder.normal(rs*sc, rs*ss, -rc);
  60                         if(tangent_attr)
  61                         {
  62                                 builder.attrib(tangent_attr, -ss, sc, 0);
  63                                 builder.attrib(binormal_attr, rc*sc, rc*ss, rs);
  64                         }
  65                         builder.texcoord(j*u_scale, v);
  66                         builder.vertex(rs*sc*radius, rs*ss*radius, cz-rc*radius);
  67                 }
  68         }
  69         builder.normal(0, 0, 1);
  70         builder.texcoord(0.5, (length+radius*M_PI)*v_scale);
  71         builder.vertex(0, 0, length/2-radius);
  72
  73         for(unsigned i=0; i<segments; ++i)
  74         {
  75                 builder.begin(GL::TRIANGLE_STRIP);
  76                 builder.element(0);
  77                 for(unsigned j=0; j+1<rings; ++j)
  78                 {
  79                         builder.element(1+j*(segments+1)+i+1);
  80                         builder.element(1+j*(segments+1)+i);
  81                 }
  82                 builder.element((segments+1)*(rings-1)+1);
  83                 builder.end();
  84         }
  85 }
  86
  87 } // namespace GL
  88 } // namespace Msp