1// This file is part of Eigen, a lightweight C++ template library
2// for linear algebra.
3//
4// Copyright (C) 2008 Gael Guennebaud <gael.guennebaud@inria.fr>
5//
6// This Source Code Form is subject to the terms of the Mozilla
7// Public License v. 2.0. If a copy of the MPL was not distributed
8// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
9
10#include "icosphere.h"
11
12#include <GL/gl.h>
13#include <map>
14
15using namespace Eigen;
16
17//--------------------------------------------------------------------------------
18// icosahedron data
19//--------------------------------------------------------------------------------
20#define X .525731112119133606
21#define Z .850650808352039932
22
23static GLfloat vdata[12][3] = {
24   {-X, 0.0, Z}, {X, 0.0, Z}, {-X, 0.0, -Z}, {X, 0.0, -Z},
25   {0.0, Z, X}, {0.0, Z, -X}, {0.0, -Z, X}, {0.0, -Z, -X},
26   {Z, X, 0.0}, {-Z, X, 0.0}, {Z, -X, 0.0}, {-Z, -X, 0.0}
27};
28
29static GLint tindices[20][3] = {
30   {0,4,1}, {0,9,4}, {9,5,4}, {4,5,8}, {4,8,1},
31   {8,10,1}, {8,3,10}, {5,3,8}, {5,2,3}, {2,7,3},
32   {7,10,3}, {7,6,10}, {7,11,6}, {11,0,6}, {0,1,6},
33   {6,1,10}, {9,0,11}, {9,11,2}, {9,2,5}, {7,2,11} };
34//--------------------------------------------------------------------------------
35
36IcoSphere::IcoSphere(unsigned int levels)
37{
38  // init with an icosahedron
39  for (int i = 0; i < 12; i++)
40    mVertices.push_back(Map<Vector3f>(vdata[i]));
41  mIndices.push_back(new std::vector<int>);
42  std::vector<int>& indices = *mIndices.back();
43  for (int i = 0; i < 20; i++)
44  {
45    for (int k = 0; k < 3; k++)
46      indices.push_back(tindices[i][k]);
47  }
48  mListIds.push_back(0);
49
50  while(mIndices.size()<levels)
51    _subdivide();
52}
53
54const std::vector<int>& IcoSphere::indices(int level) const
55{
56  while (level>=int(mIndices.size()))
57    const_cast<IcoSphere*>(this)->_subdivide();
58  return *mIndices[level];
59}
60
61void IcoSphere::_subdivide(void)
62{
63  typedef unsigned long long Key;
64  std::map<Key,int> edgeMap;
65  const std::vector<int>& indices = *mIndices.back();
66  mIndices.push_back(new std::vector<int>);
67  std::vector<int>& refinedIndices = *mIndices.back();
68  int end = indices.size();
69  for (int i=0; i<end; i+=3)
70  {
71    int ids0[3],  // indices of outer vertices
72        ids1[3];  // indices of edge vertices
73    for (int k=0; k<3; ++k)
74    {
75      int k1 = (k+1)%3;
76      int e0 = indices[i+k];
77      int e1 = indices[i+k1];
78      ids0[k] = e0;
79      if (e1>e0)
80        std::swap(e0,e1);
81      Key edgeKey = Key(e0) | (Key(e1)<<32);
82      std::map<Key,int>::iterator it = edgeMap.find(edgeKey);
83      if (it==edgeMap.end())
84      {
85        ids1[k] = mVertices.size();
86        edgeMap[edgeKey] = ids1[k];
87        mVertices.push_back( (mVertices[e0]+mVertices[e1]).normalized() );
88      }
89      else
90        ids1[k] = it->second;
91    }
92    refinedIndices.push_back(ids0[0]); refinedIndices.push_back(ids1[0]); refinedIndices.push_back(ids1[2]);
93    refinedIndices.push_back(ids0[1]); refinedIndices.push_back(ids1[1]); refinedIndices.push_back(ids1[0]);
94    refinedIndices.push_back(ids0[2]); refinedIndices.push_back(ids1[2]); refinedIndices.push_back(ids1[1]);
95    refinedIndices.push_back(ids1[0]); refinedIndices.push_back(ids1[1]); refinedIndices.push_back(ids1[2]);
96  }
97  mListIds.push_back(0);
98}
99
100void IcoSphere::draw(int level)
101{
102  while (level>=int(mIndices.size()))
103    const_cast<IcoSphere*>(this)->_subdivide();
104  if (mListIds[level]==0)
105  {
106    mListIds[level] = glGenLists(1);
107    glNewList(mListIds[level], GL_COMPILE);
108      glVertexPointer(3, GL_FLOAT, 0, mVertices[0].data());
109      glNormalPointer(GL_FLOAT, 0, mVertices[0].data());
110      glEnableClientState(GL_VERTEX_ARRAY);
111      glEnableClientState(GL_NORMAL_ARRAY);
112      glDrawElements(GL_TRIANGLES, mIndices[level]->size(), GL_UNSIGNED_INT, &(mIndices[level]->at(0)));
113      glDisableClientState(GL_VERTEX_ARRAY);
114      glDisableClientState(GL_NORMAL_ARRAY);
115    glEndList();
116  }
117  glCallList(mListIds[level]);
118}
119
120
121