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.)
• Optionally, the profile to look into (as of 2.4, by default, it looks in any and all profiles; potentially mixing them. Selecting the technique_common profile is impossible--this will change in 2.5.)

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;
}