Function makeLocalSpheres

modules/mpi/tutorials/ospMPIDistribTutorialSpheres.cpp:177–238

}

cpp::Instance makeLocalSpheres(
    const int mpiRank, const int mpiWorldSize, box3f &bounds)
{
  const float sphereRadius = 0.1;
  std::vector<vec3f> spheres(50);

  // To simulate loading a shared dataset all ranks generate the same
  // sphere data.
  std::random_device rd;
  std::mt19937 rng(rd());

  const vec3i grid = computeGrid(mpiWorldSize);
  const vec3i brickId(mpiRank % grid.x,
      (mpiRank / grid.x) % grid.y,
      mpiRank / (grid.x * grid.y));

  // The grid is over the [-1, 1] box
  const vec3f brickSize = vec3f(2.0) / vec3f(grid);
  const vec3f brickLower = brickSize * brickId - vec3f(1.f);
  const vec3f brickUpper = brickSize * brickId - vec3f(1.f) + brickSize;

  bounds.lower = brickLower;
  bounds.upper = brickUpper;

  // Generate spheres within the box padded by the radius, so we don't need
  // to worry about ghost bounds
  std::uniform_real_distribution<float> distX(
      brickLower.x + sphereRadius, brickUpper.x - sphereRadius);
  std::uniform_real_distribution<float> distY(
      brickLower.y + sphereRadius, brickUpper.y - sphereRadius);
  std::uniform_real_distribution<float> distZ(
      brickLower.z + sphereRadius, brickUpper.z - sphereRadius);

  for (auto &s : spheres) {
    s.x = distX(rng);
    s.y = distY(rng);
    s.z = distZ(rng);
  }

  cpp::Geometry sphereGeom("sphere");
  sphereGeom.setParam("radius", sphereRadius);
  sphereGeom.setParam("sphere.position", cpp::CopiedData(spheres));
  sphereGeom.commit();

  vec3f color(0.f, 0.f, (mpiRank + 1.f) / mpiWorldSize);
  cpp::Material material("obj");
  material.setParam("kd", color);
  material.commit();

  cpp::GeometricModel model(sphereGeom);
  model.setParam("material", material);
  model.commit();

  cpp::Group group;
  group.setParam("geometry", cpp::CopiedData(model));
  group.commit();

  cpp::Instance instance(group);