// This method inspects the JSON blob stored in the 'USD_UserExportedAttributesJson'
// attribute on the Maya node at dagPath and exports any attributes specified
// there onto usdPrim at time usdTime. The JSON should contain an object that
// maps Maya attribute names to other JSON objects that contain metadata about
// how to export the attribute into USD. For example:
//
// {
// "myMayaAttributeOne": {
// },
// "myMayaAttributeTwo": {
// "usdAttrName": "my:namespace:attributeTwo"
// }
// }
//
// If the attribute metadata contains a value for "usdAttrName", the attribute
// will be given that name in USD. Otherwise, the Maya attribute name will be
// used. Maya attributes in the JSON will be processed in sorted order, and any
// USD attribute name collisions will be resolved by using the first attribute
// visited and warning about subsequent attribute tags.
//
bool
PxrUsdMayaWriteUtil::WriteUserExportedAttributes(
const MDagPath& dagPath,
const UsdPrim& usdPrim,
const UsdTimeCode& usdTime)
{
MStatus status;
MFnDependencyNode depFn(dagPath.node());
MPlug exportedAttrsJsonPlug = depFn.findPlug(
_tokens->USD_UserExportedAttributesJson.GetText(), true, &status);
if (status != MS::kSuccess || exportedAttrsJsonPlug.isNull()) {
// No attributes specified for export on this node.
return false;
}
std::string exportedAttrsJsonString(exportedAttrsJsonPlug.asString().asChar());
if (exportedAttrsJsonString.empty()) {
return false;
}
JsParseError jsError;
JsValue jsValue = JsParseString(exportedAttrsJsonString, &jsError);
if (not jsValue) {
MString errorMsg(TfStringPrintf(
"Failed to parse USD exported attributes JSON on node at dagPath '%s'"
" at line %d, column %d: %s",
dagPath.fullPathName().asChar(),
jsError.line, jsError.column, jsError.reason.c_str()).c_str());
MGlobal::displayError(errorMsg);
return false;
}
// Maintain a set of USD attribute names that have been processed. If an
// attribute is multiply-defined, we'll use the first tag encountered and
// issue warnings for the subsequent definitions. JsObject is really just a
// std::map, so we'll be considering attributes in sorted order.
std::set<std::string> exportedUsdAttrNames;
JsObject exportedAttrs = jsValue.GetObject();
for (JsObject::const_iterator iter = exportedAttrs.begin();
iter != exportedAttrs.end();
++iter) {
const std::string mayaAttrName = iter->first;
const MPlug attrPlug = depFn.findPlug(mayaAttrName.c_str(), true, &status);
if (status != MS::kSuccess || attrPlug.isNull()) {
MString errorMsg(TfStringPrintf(
"Could not find attribute '%s' for USD export on node at dagPath '%s'",
mayaAttrName.c_str(), dagPath.fullPathName().asChar()).c_str());
MGlobal::displayError(errorMsg);
continue;
}
const JsObject attrMetadata = iter->second.GetObject();
// Check the metadata to see if the USD attribute name should be
// different than the Maya attribute name.
std::string usdAttrName = mayaAttrName;
JsObject::const_iterator usdAttrValueIter = attrMetadata.find(_tokens->usdAttrName);
if (usdAttrValueIter != attrMetadata.end()) {
std::string nameValue = usdAttrValueIter->second.GetString();
if (not nameValue.empty()) {
usdAttrName = nameValue;
}
}
const auto& insertIter = exportedUsdAttrNames.insert(usdAttrName);
if (not insertIter.second) {
MString errorMsg(TfStringPrintf(
"Ignoring duplicate USD export tag for attribute '%s' on node at dagPath '%s'",
usdAttrName.c_str(), dagPath.fullPathName().asChar()).c_str());
MGlobal::displayError(errorMsg);
continue;
}
UsdAttribute usdAttr = PxrUsdMayaWriteUtil::GetOrCreateUsdAttr(
attrPlug, usdPrim, usdAttrName, true);
if (usdAttr) {
PxrUsdMayaWriteUtil::SetUsdAttr(attrPlug, usdAttr, usdTime);
}
}
return true;
}
