/*
* Subdivides or unsubdivides this quad based on the current
* viewer distance to this quad, relatively to its size. This
* method uses the current viewer position provided by the
* TerrainNode to which this quadtree belongs.
*/
public void Update()
{
Frustum.VISIBILTY v = (m_parent == null) ? Frustum.VISIBILTY.PARTIALLY : m_parent.GetVisible();
if (v == Frustum.VISIBILTY.PARTIALLY)
{
m_visible = m_owner.GetVisibility(m_localBox);
}
else
{
m_visible = v;
}
// here we reuse the occlusion test from the previous frame:
// if the quad was found unoccluded in the previous frame, we suppose it is
// still unoccluded at this frame. If it was found occluded, we perform
// an occlusion test to check if it is still occluded.
if (m_visible != Frustum.VISIBILTY.INVISIBLE && m_occluded)
{
m_occluded = m_owner.IsOccluded(m_localBox);
if (m_occluded)
{
m_visible = Frustum.VISIBILTY.INVISIBLE;
}
}
double ground = m_owner.GetView().GetGroundHeight();
double dist = m_owner.GetCameraDist(new Box3d(m_ox, m_ox + m_length, m_oy, m_oy + m_length, Math.Min(0.0, ground), Math.Max(0.0, ground)));
if ((m_owner.GetSplitInvisibleQuads() || m_visible != Frustum.VISIBILTY.INVISIBLE) && dist < m_length * m_owner.GetSplitDist() && m_level < m_owner.GetMaxLevel())
{
if (IsLeaf())
{
Subdivide();
}
int[] order = new int[4];
double ox = m_owner.GetLocalCameraPos().x;
double oy = m_owner.GetLocalCameraPos().y;
double cx = m_ox + m_length / 2.0;
double cy = m_oy + m_length / 2.0;
if (oy < cy)
{
if (ox < cx)
{
order[0] = 0;
order[1] = 1;
order[2] = 2;
order[3] = 3;
}
else
{
order[0] = 1;
order[1] = 0;
order[2] = 3;
order[3] = 2;
}
}
else
{
if (ox < cx)
{
order[0] = 2;
order[1] = 0;
order[2] = 3;
order[3] = 1;
}
else
{
order[0] = 3;
order[1] = 1;
order[2] = 2;
order[3] = 0;
}
}
m_children[order[0]].Update();
m_children[order[1]].Update();
m_children[order[2]].Update();
m_children[order[3]].Update();
// we compute a more precise occlusion for the next frame (see above),
// by combining the occlusion status of the child nodes
m_occluded = (m_children[0].GetOccluded() && m_children[1].GetOccluded() && m_children[2].GetOccluded() && m_children[3].GetOccluded());
}
else
{
if (m_visible != Frustum.VISIBILTY.INVISIBLE)
{
// we add the bounding box of this quad to the occluders list
m_occluded = m_owner.AddOccluder(m_localBox);
if (m_occluded)
{
m_visible = Frustum.VISIBILTY.INVISIBLE;
}
}
if (!IsLeaf())
{
Release();
}
}
}
