From 8db382c1127c0257d9c5a3caa0941ca66e0cd0c2 Mon Sep 17 00:00:00 2001
From: Patrick Owen <patowen95@gmail.com>
Date: Fri, 27 Oct 2023 19:34:23 -0400
Subject: [PATCH] Allow clients to handle block updates for unloaded chunks

---
 client/src/graphics/voxels/mod.rs |  9 +++++++++
 client/src/sim.rs                 | 10 +++++++---
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/client/src/graphics/voxels/mod.rs b/client/src/graphics/voxels/mod.rs
index f824d6df..ec72970a 100644
--- a/client/src/graphics/voxels/mod.rs
+++ b/client/src/graphics/voxels/mod.rs
@@ -103,6 +103,15 @@ impl Voxels {
             let chunk_id = ChunkId::new(chunk.node, chunk.chunk);
             sim.graph
                 .populate_chunk(sim.cfg.chunk_size, chunk_id, chunk.voxels, false);
+
+            // Now that the block is populated, we can apply any pending block updates the server
+            // provided that the client couldn't apply.
+            if let Some(block_updates) = sim.pending_modified_chunks.remove(&chunk_id) {
+                for block_update in block_updates {
+                    // The chunk was just populated, so a block update should always succeed.
+                    assert!(sim.graph.update_block(sim.cfg.chunk_size, &block_update));
+                }
+            }
         }
 
         // Determine what to load/render
diff --git a/client/src/sim.rs b/client/src/sim.rs
index 7314c058..5a8dffa9 100644
--- a/client/src/sim.rs
+++ b/client/src/sim.rs
@@ -12,7 +12,7 @@ use common::{
     collision_math::Ray,
     graph::{Graph, NodeId},
     graph_ray_casting,
-    node::{populate_fresh_nodes, VoxelData},
+    node::{populate_fresh_nodes, ChunkId, VoxelData},
     proto::{
         self, BlockUpdate, Character, CharacterInput, CharacterState, Command, Component, Position,
     },
@@ -25,6 +25,7 @@ use common::{
 pub struct Sim {
     // World state
     pub graph: Graph,
+    pub pending_modified_chunks: FxHashMap<ChunkId, Vec<BlockUpdate>>,
     pub graph_entities: GraphEntities,
     entity_ids: FxHashMap<EntityId, Entity>,
     pub world: hecs::World,
@@ -67,6 +68,7 @@ impl Sim {
         populate_fresh_nodes(&mut graph);
         Self {
             graph,
+            pending_modified_chunks: FxHashMap::default(),
             graph_entities: GraphEntities::new(),
             entity_ids: FxHashMap::default(),
             world: hecs::World::new(),
@@ -301,8 +303,10 @@ impl Sim {
         populate_fresh_nodes(&mut self.graph);
         for block_update in msg.block_updates.into_iter() {
             if !self.graph.update_block(self.cfg.chunk_size, &block_update) {
-                // TODO: This case should be handled to properly support multiple players.
-                tracing::error!("Voxel data received from server for ungenerated chunk.")
+                self.pending_modified_chunks
+                    .entry(block_update.chunk_id)
+                    .or_default()
+                    .push(block_update);
             }
         }
         for (chunk_id, voxel_data) in msg.modified_chunks {