From 22f95edf32803683e366c873b1679ca71a802dd6 Mon Sep 17 00:00:00 2001
From: Joshua Barretto <joshua.s.barretto@gmail.com>
Date: Fri, 25 Jun 2021 13:21:03 +0100
Subject: [PATCH] Added reset system for unused persisted blocks

---
 server/src/sys/terrain.rs         | 15 +++++++++++++--
 server/src/terrain_persistence.rs |  4 ++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/server/src/sys/terrain.rs b/server/src/sys/terrain.rs
index 0a64f0269b..dcc0fa2f5b 100644
--- a/server/src/sys/terrain.rs
+++ b/server/src/sys/terrain.rs
@@ -156,8 +156,19 @@ impl<'a> System<'a> for Sys {
                 },
             };
 
-            for (key, block) in terrain_persistence.load_chunk(key).blocks() {
-                chunk.set(key, block);
+            // Terrain persistence
+            let mut resets = Vec::new();
+            for (rpos, new_block) in terrain_persistence.load_chunk(key).blocks() {
+                chunk.map(rpos, |block| {
+                    if block == new_block {
+                        resets.push(rpos);
+                    }
+                    new_block
+                });
+            }
+            // Reset any unchanged blocks
+            for rpos in resets {
+                terrain_persistence.reset_block(key, rpos);
             }
 
             // Arcify the chunk
diff --git a/server/src/terrain_persistence.rs b/server/src/terrain_persistence.rs
index 67769c1b1b..91df2b4625 100644
--- a/server/src/terrain_persistence.rs
+++ b/server/src/terrain_persistence.rs
@@ -103,6 +103,10 @@ impl TerrainPersistence {
         let key = pos.xy().map2(TerrainChunk::RECT_SIZE, |e, sz| e.div_euclid(sz as i32));
         self.load_chunk(key).blocks.insert(pos - key * TerrainChunk::RECT_SIZE.map(|e| e as i32), block);
     }
+
+    pub fn reset_block(&mut self, key: Vec2<i32>, rpos: Vec3<i32>) {
+        self.load_chunk(key).blocks.remove(&rpos);
+    }
 }
 
 #[derive(Default, Serialize, Deserialize)]