Serialize Vector3i and Vector3d types. (#3)

* Serialize Vector3i and Vector3d types.

Signed-off-by: Arjo Chakravarty <[email protected]>

* style fix

Signed-off-by: Arjo Chakravarty <[email protected]>

---------

Signed-off-by: Arjo Chakravarty <[email protected]>

Author: arjo129

sdformat_rs/src/lib.rs

@@ -151,9 +151,19 @@ impl YaDeserialize for Vector3d {
 }
 
 impl YaSerialize for Vector3d {
-    fn serialize<W: Write>(&self, _writer: &mut yaserde::ser::Serializer<W>) -> Result<(), String> {
+    fn serialize<W: Write>(
+        &self,
+        serializer: &mut yaserde::ser::Serializer<W>,
+    ) -> Result<(), String> {
         // serializer code
-        Err("Not yet implemented".to_string())
+        serializer
+            .write(xml::writer::XmlEvent::Characters(&format!(
+                "{} {} {}",
+                self.0.x, self.0.y, self.0.z
+            )))
+            .map_err(|e| e.to_string())?;
+
+        Ok(())
     }
 
     fn serialize_attributes(
@@ -191,9 +201,19 @@ impl YaDeserialize for Vector3i {
 }
 
 impl YaSerialize for Vector3i {
-    fn serialize<W: Write>(&self, _writer: &mut yaserde::ser::Serializer<W>) -> Result<(), String> {
+    fn serialize<W: Write>(
+        &self,
+        serializer: &mut yaserde::ser::Serializer<W>,
+    ) -> Result<(), String> {
         // serializer code
-        Err("Not yet implemented".to_string())
+        serializer
+            .write(xml::writer::XmlEvent::Characters(&format!(
+                "{} {} {}",
+                self.0.x, self.0.y, self.0.z
+            )))
+            .map_err(|e| e.to_string())?;
+
+        Ok(())
     }
 
     fn serialize_attributes(