Tree building function from precalculated tree
I am building a binary tree. The binary tree is pre-built in a file and I need to construct it. Due to the way it is structured, I read the tree into an array. Each tree nodes look something like this.
struct Tree_Node
{
float normalX;
float normalY;
float normalZ;
float splitdistance;
long region;
long left, right; //array index
Tree_Node* left_node; // pointer to left node
Tree_Node* right_node; // pointer to right node
} typedef Tree_Node;
I have tried a number of ways to write some code that will build the tree. Let me give you some pseudocode so you understand what I am trying to do.
- Read in head node. Node is number one in the array.
- If the node has a right and left array index, create new nodes and insert the information from the array indicies into that tree node.
- If the node does not have a right and left index, it is a leaf node.
Here is my building function:
void WLD::treeInsert(BSP_Node *tree_root, int node_number)
{
/// Add the item to the binary sort tree to which the parameter
// "root" refers. Note that root is passed by reference since
// its value can change in the case where the tree is empty.
if ( tree_root == NULL )
{
// The tree is empty. Set root to point to a new node containing
// the new item. This becomes the only node in the tree.
tree_root = new BSP_Node();
tree_root->normalX = bsp_array[node_number].normal[0];
tree_root->normalY = bsp_array[node_number].normal[1];
tree_root->normalZ = bsp_array[node_number].normal[2];
tree_root->splitdistance = bsp_array[node_number].splitdistance;;
tree_root->region = bsp_array[node_number].region;
tree_root->left = bsp_array[node_number].left;
tree_root->right = bsp_array[node_number].right;
tree_root->left_node[node_number];
tree_root->right_node[node_number];
errorLog.OutputSuccess("Inserting new root node: %i", node_number);
// NOTE: The left and right subtrees of root
// are automatically set to NULL by the constructor.
// This is important...
}
if ( tre开发者_运维知识库e_root->left != 0 )
{
errorLog.OutputSuccess("Inserting left node number: %i!", tree_root->left);
treeInsert( tree_root->left_node, tree_root->left );
}
else if ( tree_root->right != 0 )
{
errorLog.OutputSuccess("Inserting right node: %i!", tree_root->right);
treeInsert( tree_root->right_node, tree_root->right );
}
else if ( tree_root->right == 0 && tree_root->left == 0)
{
errorLog.OutputSuccess("Reached a leaf node!");
return;
}
else
{
errorLog.OutputError("Unknown BSP tree error!");
}
}
My debug shows that the function tries to insert node 2 until the program crashes.
Can someone help me with this?
tree_root->left_node[node_number];
I don't see any code that initializes this array, so this'll be referring to something invalid.
Then by the time you come around to the next function
treeInsert( tree_root->left_node, tree_root->left );
treeInsert
will be called with an invalid pointer, since left_node
doesn't go anywhere.
I imagine you need something like tree_root->left_node = NULL
instead of tree_root->left_node[node_number]
so that the recursive call to treeInsert creates the next node.
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