List <Task <IQuadNode> > CreateBackgroundSplitTasks(DoubleVector3 cameraLocation, DoubleVector3 planetLocation)
{
// TODO: there's a problem with this algorithm. If we need to split very deeply because for example
// the camera is teleported to the surface, we only split one level at a time and wait for that level
// to finish and for the next update sweep to occur before queuing splits for the next level. There
// may be wasted time in there (not clear yet). We also spend time generating meshes for quads that
// we know we don't need. Ideally we'd jump straight to rendering meshes for the new leaves and worry
// about rendering meshes for the intermediate nodes later when we need them. This means we need a
// general way to delay completing a merge (continuing to render its children in the meantime) until
// a mesh is rendered for that node. Once we have that behavior
// we can maybe throw away the vertex buffers for all non-leaf meshes to save memory and regenerate them
// as needed. That would take more CPU overall but it's not time sensitive because we'd just keep
// rendering the child nodes until we got around to it. That would be a problem only if we end up
// overloading the GPU but in many cases that wouldn't happen because the merging nodes would be behind
// the camera as it travels and thus not rendered.
// Potential problem: we don't know for sure if a node needs to be split until after we generate its mesh.
_splitInProgress = true;
var subextents = _extents.Split();
return(subextents.Select(extent => Task <IQuadNode> .Factory.StartNew(() =>
{
var node = _quadNodeFactory.Create();
node.Initialize(_planetRadius, _planeNormalVector, _uVector, _vVector, extent, Level + 1);
node.Update(cameraLocation, planetLocation);
return node;
}, _cancellationTokenSource.Token, TaskCreationOptions.None, _taskSchedulerFactory.CreateForLevel(Level))).ToList());
}
private IQuadNode CreateFace(double planetRadius, Vector3 normalVector)
{
var face = _quadNodeFactory.Create();
var orientationVectors = _faceOrientations[normalVector];
var u = orientationVectors[0];
var v = orientationVectors[1];
face.Initialize(planetRadius, normalVector, u, v, new QuadNodeExtents(-1.0, 1.0, -1.0, 1.0), 0);
return(face);
}
