Developer Documentation
MeshNode2.cc
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41 
42 
43 
44 #include <ACG/GL/acg_glew.hh>
45 #include "MeshNode2T.hh"
46 
47 namespace ACG {
48 namespace SceneGraph {
49 
50 MeshNodeBase::MeshNodeBase(BaseNode* _parent, std::string _name) :
51  BaseNode(_parent, _name),
52  drawMeshBase_(0),
53  polyEdgeBuf_(0),
54  polyEdgeBufSize_(0),
55  polyEdgeBufTex_(0) {
56 }
57 
58 void MeshNodeBase::supplyDrawMesh(DrawMeshBase *drawMeshBase) {
59  /*
60  * We take the luxury of checking these conditions even in release
61  * mode as this method is rarely called.
62  */
63  if (drawMeshBase_)
64  throw std::runtime_error("MeshNodeBase::supplyDrawMesh called "
65  "more than once.");
66  if (!drawMeshBase)
67  throw std::runtime_error("MeshNodeBase::supplyDrawMesh called "
68  "with NULL parameter.");
69 
70  drawMeshBase_ = drawMeshBase;
71 }
72 
73 void MeshNodeBase::updatePolyEdgeBuf()
74 {
76 {
77  // drawMeshBase_ must have been supplied.
78  assert(drawMeshBase_);
79 
80  MeshCompiler * const mc = drawMeshBase_->getMeshCompiler();
81  if (mc && !mc->isTriangleMesh())
82  {
83  // create/update the poly-edge buffer
84  if (!polyEdgeBuf_)
85  glGenBuffers(1, &polyEdgeBuf_);
86 
87  const int nTris = mc->getNumTriangles();
88 
89  const int newBufSize = (nTris/2+1);
90 
91  if (polyEdgeBufSize_ != newBufSize)
92  {
93  glBindBuffer(GL_TEXTURE_BUFFER, polyEdgeBuf_);
94 
95  // The poly-edge buffer is a texture buffer that stores one byte for each triangle, which encodes triangle edge properties.
96  // An inner edge is an edge that was added during the triangulation of a n-poly,
97  // whereas outer edges are edges that already exist in the input mesh object.
98  // This information is used in the wireframe/hiddenline geometry shader to identify edges, which should not be rendered.
99  // Buffer storage:
100  // each triangle uses 3 bits to mark edges as visible or hidden
101  // outer edge -> bit = 1 (visible)
102  // inner edge -> bit = 0 (hidden)
103  // each byte can store edges for two triangles and the remaining 2 bits are left unused
104 
105  polyEdgeBufSize_ = newBufSize;
106  unsigned char* polyEdgeBufData = new unsigned char[newBufSize];
107 
108  // set zero
109  memset(polyEdgeBufData, 0, newBufSize);
110 
111  // build buffer
112  for (int i = 0; i < nTris; ++i)
113  {
114  int byteidx = i>>1;
115  int bitidx = (i&1) * 3;
116 
117  for (int k = 0; k < 3; ++k)
118  if (mc->isFaceEdge(i, k))
119  polyEdgeBufData[byteidx] += 1 << (k + bitidx);
120  }
121 
122  glBufferData(GL_TEXTURE_BUFFER, polyEdgeBufSize_, polyEdgeBufData, GL_STATIC_DRAW);
123 
124 
125  delete [] polyEdgeBufData;
126  polyEdgeBufData = 0;
127 
128  // create texture object for the texture buffer
129 
130  if (!polyEdgeBufTex_)
131  {
132  glGenTextures(1, &polyEdgeBufTex_);
133 
134  glActiveTexture(GL_TEXTURE0);
135  glBindTexture(GL_TEXTURE_BUFFER, polyEdgeBufTex_);
136  glTexBuffer(GL_TEXTURE_BUFFER, GL_R8UI, polyEdgeBuf_);
137 
138  glBindTexture(GL_TEXTURE_2D, 0);
139  }
140 
142  }
143  }
144 }
145 }
146 
147 
148 } /* namespace SceneGraph */
149 } /* namespace ACG */
Namespace providing different geometric functions concerning angles.
void glCheckErrors()
Definition: GLError.hh:96
void compatibilityProfile(bool _enableCoreProfile)
Store opengl core profile setting.
Definition: gl.cc:166