DOM guide: Importing documents

From COLLADA Public Wiki
Revision as of 20:01, 9 April 2008 by SteveT (talk | contribs)
Jump to: navigation, search

Be sure to read the section on creating documents first. It covers some important topics relevant to this section.

A simple example

Let's begin with a simple example of reading some information from a Collada document. We'll open the document and print the ID of the first <node> we find.

DAE dae;
daeElement* root = dae.open("simpleImport.dae");
if (!root) {
    cout << "Document import failed.\n";
    return 0;
}

We create the DAE object then call DAE::open to open a file called "simpleImport.dae". If there is no file of that name in the current directory, or the file failed to open for some other reason, then the DAE::open method will return null. We check for that and print an error message if opening the document failed.

daeElement* node = root->getDescendant("node");
if (!node)
    cout << "No nodes found\n";
else
    cout << "node id: " << node->getAttribute("id") << endl;

Here we use the daeElement::getDescendant method to do a breadth-first search through the xml element tree for an element with the given name. This method will return null if it couldn't find an element with a matching name, which we check for. If it did find a matching element we use the daeElement::getAttribute method to print the value of the 'id' attribute.

The complete code.

#include <iostream>
#include <dae.h>
#include <dom/domCOLLADA.h>
using namespace std;

int main() {
	DAE dae;
	daeElement* root = dae.open("simpleImport.dae");
	if (!root) {
		cout << "Document import failed.\n";
		return 0;
	}

	daeElement* node = root->getDescendant("node");
	if (!node)
		cout << "No nodes found\n";
	else
		cout << "node id: " << node->getAttribute("id") << endl;

	return 0;
}

The simpleImport.dae document.

<?xml version="1.0" encoding="UTF-8"?>
<COLLADA xmlns="http://www.collada.org/2005/11/COLLADASchema" version="1.4.1">
	<asset>
		<contributor/>
		<created>2008-04-08T13:07:52-08:00</created>
		<modified>2008-04-08T13:07:52-08:00</modified>
	</asset>
  <library_nodes>
    <node id="hello"/>
  </library_nodes>
</COLLADA>

And the results of running the program.

node id: hello