private void RefineNode(TerrainPatch patch, Transform playerTransform, ref List <TerrainPatch> active)
{
int x = GetQuadX(patch);
int z = GetQuadZ(patch);
// 视景体剔除
if (!GeometryUtility.TestPlanesAABB(frustum, patch.bound))
{
quadMatrix[z * quadSize + x] = 0;
DisableRenderer(patch);
return;
}
Vector3 cameraPos = playerTransform.position;
Vector3 facePos = patch.center;
//calculate the distance from the current point (L1 NORM, which, essentially, is a faster version of the
//normal distance equation you may be used to... yet again, thanks to Chris Cookson)
int v1 = GetQuadMatrixData(x + 1, z);
float viewDistance = (float)(Mathf.Abs(cameraPos.x - (facePos.x)) +
Mathf.Abs(cameraPos.y - v1) +
Mathf.Abs(cameraPos.z - (facePos.z)));
//compute the 'f' value (as stated in Roettger's whitepaper of this algorithm)
int v2 = GetQuadMatrixData(x - 1, z);
float f = viewDistance / (patch.scale * minResolution *
Mathf.Max(detailLevel * v2 / 4.0f, 1.0f));
int blend;
if (f >= 1)
{
blend = 0;
}
else
{
blend = 255;
}
quadMatrix[z * quadSize + x] = blend;
// 不需要拆分
if (blend == 0)
{
active.Add(patch);
if (patch.tree != null)
{
// 合并前恢复原始值
for (int i = 0; i < patch.tree.Length; i++)
{
int childX = GetQuadX(patch.tree[i]);
int childZ = GetQuadZ(patch.tree[i]);
quadMatrix[childZ * quadSize + childX] = quadMatrix[childZ * quadSize + childX - 1];
}
quadMatrix[z * quadSize + x] = quadMatrix[z * quadSize + x - 1];
patch.Merge();
}
}
// 需要拆分
else if (patch.scale >= 4)
{
if (patch.tree == null)
{
patch.SubDivide();
}
}
// 计算子节点递归
if (patch.tree != null)
{
for (int i = 0; i < patch.tree.Length; i++)
{
RefineNode(patch.tree[i], playerTransform, ref active);
}
}
}