Include voxel data in world saves

Not yet testable, as world loads are unimplemented

server/src/sim.rs

@@ -36,6 +36,7 @@ pub struct Sim {
     despawns: Vec<EntityId>,
     graph_entities: GraphEntities,
     dirty_nodes: FxHashSet<NodeId>,
+    dirty_voxel_nodes: FxHashSet<NodeId>,
     modified_chunks: FxHashMap<u128, FxHashSet<Vertex>>,
 }
 
@@ -52,6 +53,7 @@ impl Sim {
             despawns: Vec::new(),
             graph_entities: GraphEntities::new(),
             dirty_nodes: FxHashSet::default(),
+            dirty_voxel_nodes: FxHashSet::default(),
             modified_chunks: FxHashMap::default(),
         };
 
@@ -86,10 +88,15 @@ impl Sim {
         }
 
         let dirty_nodes = self.dirty_nodes.drain().collect::<Vec<_>>();
+        let dirty_voxel_nodes = self.dirty_voxel_nodes.drain().collect::<Vec<_>>();
         for node in dirty_nodes {
             let entities = self.snapshot_node(node);
             writer.put_entity_node(self.graph.hash_of(node), &entities)?;
         }
+        for node in dirty_voxel_nodes {
+            let voxels = self.snapshot_voxel_node(node);
+            writer.put_voxel_node(self.graph.hash_of(node), &voxels)?;
+        }
 
         drop(writer);
         tx.commit()?;
@@ -128,6 +135,27 @@ impl Sim {
         }
     }
 
+    fn snapshot_voxel_node(&self, node: NodeId) -> save::VoxelNode {
+        let mut chunks = vec![];
+        let node_data = self.graph.get(node).as_ref().unwrap();
+        for &vertex in self.modified_chunks.get(&self.graph.hash_of(node)).unwrap() {
+            let mut serialized_voxels = Vec::new();
+            let Chunk::Populated { ref voxels, .. } = node_data.chunks[vertex] else {
+                panic!("Unknown chunk listed as modified");
+            };
+            postcard_helpers::serialize(
+                &voxels.to_serializable(self.cfg.chunk_size),
+                &mut serialized_voxels,
+            )
+            .unwrap();
+            chunks.push(save::Chunk {
+                vertex: vertex as u32,
+                voxels: serialized_voxels,
+            })
+        }
+        save::VoxelNode { chunks }
+    }
+
     pub fn spawn_character(&mut self, hello: ClientHello) -> (EntityId, Entity) {
         let id = self.new_id();
         info!(%id, name = %hello.name, "spawning character");