Added functionality for user payload data in mjSpec.

PiperOrigin-RevId: 738343134
Change-Id: I6217362ced9993afcd5a2914c78718ffe3bf753a

src/user/user_api.cc

@@ -769,6 +769,30 @@ mjsFrame* mjs_bodyToFrame(mjsBody** body) {
 
 
 
+// set user payload
+void mjs_setUserValue(mjsElement* element, const char* key, const void* data) {
+  mjCBase* baseC = static_cast<mjCBase*>(element);
+  baseC->SetUserValue(key, data);
+}
+
+
+
+// return user payload or NULL if none found
+const void* mjs_getUserValue(mjsElement* element, const char* key) {
+  mjCBase* baseC = static_cast<mjCBase*>(element);
+  return baseC->GetUserValue(key);
+}
+
+
+
+// delete user payload
+void mjs_deleteUserValue(mjsElement* element, const char* key) {
+  mjCBase* baseC = static_cast<mjCBase*>(element);
+  baseC->DeleteUserValue(key);
+}
+
+
+
 // get id
 int mjs_getId(mjsElement* element) {
   if (!element) {