void Terrain::RenewNodes(const vec3& viewpoint, const QuadTree<TerrainNode>::Iterator& node)
{
//Check if this node must be enabled using morph-factor
float sz = static_cast<float>(node.LayerSize());
float l = node.Offset().x / sz, r = (node.Offset().x + 1) / sz;
float u = node.Offset().y / sz, d = (node.Offset().y + 1) / sz;
vec3 rel_pos = vec3(inverse(GetModelMatrix()) * vec4(viewpoint, 1.0f));
rel_pos.x = ClosestSegmentPoint(rel_pos.x, l, r);
rel_pos.y = ClosestSegmentPoint(rel_pos.y, node->heights.x, node->heights.y);
rel_pos.z = ClosestSegmentPoint(rel_pos.z, u, d);
if (length(rel_pos)*length(rel_pos) /
(1.0f + node->heights.y - node->heights.x) /
(r - l) / (d - u) > 5.0f ||
node.Level() == maxLOD)
{
//This node is probably enabled
}
else
{
//This node is not enabled
//continue checking its children
DisableNodes(node);
RenewNodes(viewpoint, node.Child(1));
RenewNodes(viewpoint, node.Child(0));
RenewNodes(viewpoint, node.Child(3));
RenewNodes(viewpoint, node.Child(2));
}
}
void Terrain::EnableNodes(const QuadTree<TerrainNode>::Iterator& node)
{
node->enabled = true;
for (int i = 0; i < QTREE_CHILDREN_COUNT; i++)
{
if (node.Child(i))
EnableNodes(node.Child(i));
}
}
void Terrain::UnloadVertices(const QuadTree<TerrainNode>::Iterator& node)
{
if (node->vaoID)
{
glBindBuffer(GL_ARRAY_BUFFER, 0);
glDeleteBuffers(2, node->vboID);
glBindVertexArray(0);
glDeleteVertexArrays(1, &node->vaoID);
node->vaoID = NULL;
}
for (int i = 0; i < QTREE_CHILDREN_COUNT; i++)
if (node.Child(i))
UnloadVertices(node.Child(i));
}