Function createGridGeometry

tutorials/grid_geometry/grid_geometry_device.cpp:201–508

adds a displaced sphere to the scene */

/* adds a displaced sphere to the scene */
void createGridGeometry (GridMesh& gmesh)
{
#if 1
  /* calculates top vertex ring */
  for (int i=0; i<5; i++) {
    const float theta = 45.0f*float(pi)/180.0f;
    const float phi = 72.0f*i*float(pi)/180.0f;
    sphere_vertices[i] = Vec3fa(sin(theta)*sin(phi),cos(theta),sin(theta)*cos(phi));
  }

  /* calculates center vertex ring */
  for (int i=0; i<10; i++) {
    const float theta = 90.0f*float(pi)/180.0f;
    const float phi = (18.0f+36.0f*i)*float(pi)/180.0f;
    sphere_vertices[5+i] = Vec3fa(sin(theta)*sin(phi),cos(theta),sin(theta)*cos(phi));
  }

  /* calculates bottom vertex ring */
  for (int i=0; i<5; i++) {
    const float theta = 135.0f*float(pi)/180.0f;
    const float phi = 72.0f*i*float(pi)/180.0f;
    sphere_vertices[5+10+i] = Vec3fa(sin(theta)*sin(phi),cos(theta),sin(theta)*cos(phi));
  }
#endif
  
  /* temporary subdivision geometry to evaluate base surface */
  RTCGeometry geomSubdiv = rtcNewGeometry(g_device, RTC_GEOMETRY_TYPE_SUBDIVISION);
  rtcSetSharedGeometryBuffer(geomSubdiv, RTC_BUFFER_TYPE_VERTEX, 0, RTC_FORMAT_FLOAT3, sphere_vertices, 0, sizeof(Vec3fa),       NUM_VERTICES);
  rtcSetSharedGeometryBuffer(geomSubdiv, RTC_BUFFER_TYPE_INDEX,  0, RTC_FORMAT_UINT,   sphere_indices,  0, sizeof(unsigned int), NUM_INDICES);
  rtcSetSharedGeometryBuffer(geomSubdiv, RTC_BUFFER_TYPE_FACE,   0, RTC_FORMAT_UINT,   sphere_faces,    0, sizeof(unsigned int), NUM_FACES);
  rtcCommitGeometry(geomSubdiv);

  /* grid resolution has to be uneven as non-quads are split into multiple quads */
  assert((GRID_RESOLUTION_X%2) == 1);
  assert((GRID_RESOLUTION_Y%2) == 1);

  /* subgrid resolution for non-quads */
  unsigned int SUB_GRID_RESOLUTION_X = GRID_RESOLUTION_X/2+1;
  unsigned int SUB_GRID_RESOLUTION_Y = GRID_RESOLUTION_Y/2+1;

  /* grid resolution for quads */
  unsigned int QUAD_GRID_RESOLUTION_X = GRID_RESOLUTION_X;
  unsigned int QUAD_GRID_RESOLUTION_Y = GRID_RESOLUTION_Y;
    
  /* each quad becomes one grid, other faces become multiple grids */
  int numGrids = 0;
  int numVertices = 0;
  for (int f=0; f<NUM_FACES; f++)
  {
    if (sphere_faces[f] == 4)
    {
      numGrids++;
      numVertices += QUAD_GRID_RESOLUTION_X*QUAD_GRID_RESOLUTION_Y;
    }
    else
    {
      numGrids += sphere_faces[f];
      numVertices += sphere_faces[f]*SUB_GRID_RESOLUTION_X*SUB_GRID_RESOLUTION_Y;