DOM guide: Resolving SIDs

In COLLADA, some elements are identified with a sid (scoped identifier). In the COLLADA DOM, daeSIDResolver is a helper class to resolve these COLLADA address syntax targets. It can also be used to do “sidRef”-type lookups (used often in COLLADA FX and COLLADA Physics).

Resolving normal SIDs

To resolve a normal/absolute COLLADA sid target (for example, in <animation>/<channel> elements), pass it:

• The containing element (same concept as in daeURI);
• The target string
• Optionally, the profile to look into (by default, it uses the COMMON profile)

Resolving SIDs in COLLADA FX

To “hack it” to do sid lookups used in COLLADA FX, you can pass in a relative target string. This must be done programmatically because the documents specify “sid refs” by sid alone and not in relative COLLADA addressing syntax. For example, SomeSID would become ./SomeSID. Then the container would be where to start looking.

Example

This example uses the daeSIDResolver class to find the "pelvis" joint of a skeleton.

void sidResolve() {
	DAE dae;
	char* docUri = "file:///home/sthomas/models/skinnedModel.dae";
	if (dae.load(docUri) != DAE_OK)
		return;

	// Get the first <skeleton> in the model
	daeElement* element = 0;
	dae.getDatabase()->getElement(&element, 0, 0, "skeleton");
	domInstance_controller::domSkeleton* skeleton =
		daeSafeCast<domInstance_controller::domSkeleton>(element);
	if (!skeleton)
		return;

	// Get the root node of the <skeleton>
	daeElement* skeletonRootNode = skeleton->getValue().getElement();

	// Find the joint named "pelvis". The "./" part is necessary.
	daeSIDResolver resolver(skeletonRootNode, "./pelvis");
	domNode* pelvis = daeSafeCast<domNode>(resolver.getElement());
	if (!pelvis)
		return;

	cout << pelvis->getId() << endl;
}