From bed114900f679176117e1a27005daf87e7366601 Mon Sep 17 00:00:00 2001
From: Joshua Barretto <joshua.s.barretto@gmail.com>
Date: Thu, 11 Feb 2021 01:36:42 +0000
Subject: [PATCH] Better static light propagation between translucent objects

---
 common/src/terrain/block.rs | 11 ++++++-----
 voxygen/src/mesh/terrain.rs | 21 +++++++++++----------
 2 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/common/src/terrain/block.rs b/common/src/terrain/block.rs
index f72ef8e950..d95acc9db6 100644
--- a/common/src/terrain/block.rs
+++ b/common/src/terrain/block.rs
@@ -194,13 +194,14 @@ impl Block {
         }
     }
 
+    // minimum block, attenuation
     #[inline]
-    pub fn get_max_sunlight(&self) -> Option<u8> {
+    pub fn get_max_sunlight(&self) -> (u8, u8) {
         match self.kind() {
-            BlockKind::Water => Some(4),
-            BlockKind::Leaves => Some(10),
-            _ if self.is_opaque() => Some(0),
-            _ => None,
+            BlockKind::Water => (1, 1),
+            BlockKind::Leaves => (10, 255),
+            _ if self.is_opaque() => (0, 255),
+            _ => (0, 0),
         }
     }
 
diff --git a/voxygen/src/mesh/terrain.rs b/voxygen/src/mesh/terrain.rs
index 551b3267a0..8dbf7892ae 100644
--- a/voxygen/src/mesh/terrain.rs
+++ b/voxygen/src/mesh/terrain.rs
@@ -71,20 +71,21 @@ fn calc_light<V: RectRasterableVol<Vox = Block> + ReadVol + Debug>(
             for y in 0..outer.size().h {
                 let mut light = SUNLIGHT;
                 for z in (0..outer.size().d).rev() {
-                    match vol_cached
+                    let (min_light, attenuation) = vol_cached
                         .get(outer.min + Vec3::new(x, y, z))
-                        .map_or(None, |b| b.get_max_sunlight())
-                    {
-                        None => {},
-                        Some(0) => {
-                            light_map[lm_idx(x, y, z)] = 0;
-                            break;
-                        },
-                        Some(max_sunlight) => light = light.min(max_sunlight),
+                        .map_or((0, 0), |b| b.get_max_sunlight());
+
+                    if light > min_light {
+                        light = light.saturating_sub(attenuation).max(min_light);
                     }
 
                     light_map[lm_idx(x, y, z)] = light;
-                    prop_que.push_back((x as u8, y as u8, z as u16));
+
+                    if light == 0 {
+                        break;
+                    } else {
+                        prop_que.push_back((x as u8, y as u8, z as u16));
+                    }
                 }
             }
         }