public override VectorData LoadElements(CullState cullState)
{
VectorElementVector elements = new VectorElementVector();
MapEnvelope mapViewBounds = cullState.GetProjectionEnvelope(this.Projection);
MapPos min = mapViewBounds.Bounds.Min;
MapPos max = mapViewBounds.Bounds.Max;
// Run query here
LoadData(elements, min, max, cullState.ViewState.Zoom);
return(new VectorData(elements));
}
private bool DistanceCull(float nearestDistSquare, float farthestDistSquare, IStreamingResourceHandler handler)
{
bool allowExitAhead = true;
// camera in this cell
if (nearestDistSquare < 0)
{
for (int i = 0; i < Constants.DistCullingCatCount; i++)
{
if (_cullingState[i] != CullState.NotCulled)
{
_cullingState[i] = CullState.NotCulled;
SetActivation(i, true, handler);
}
}
allowExitAhead = false;
}
else
{
// 分若干种距离判断是否需要提前退出
for (int i = 0; i < Constants.DistCullingCatCount; i++)
{
if (_cullingCountOverall[i] != 0)
{
var standard = Constants.DistCullingCats[i].Dist;
var cullStandard = _cullingState[i] == CullState.NotSure
? Constants.DistCullingCats[i].RedundantDist
: standard;
CullState state = CullState.NotSure;
if (nearestDistSquare >= cullStandard)
{
state = CullState.Culled;
}
else if (farthestDistSquare < standard)
{
state = CullState.NotCulled;
}
// 结果为剔除，上次也为剔除，提前退出
// 结果为必可见，上次也为必可见，提前退出
if (_cullingState[i] != state || state == CullState.NotSure)
{
allowExitAhead = false;
}
// 状态变化时，处理可见性
if (_cullingState[i] != state)
{
_cullingState[i] = state;
SetActivation(i, _cullingState[i] != CullState.Culled, handler);
}
}
}
}
return(allowExitAhead);
}
public void SetCullState(CullState cullstate)
{
this.cullState = cullstate;
}
