7 files changed, 13 insertions, 26 deletions
diff --git a/game/shared/entity/grounded.hh b/game/shared/entity/grounded.hh
index 940cebe..34a0f9e 100644
--- a/game/shared/entity/grounded.hh
+++ b/game/shared/entity/grounded.hh
@@ -1,8 +1,6 @@
-#ifndef SHARED_ENTITY_GROUNDED
-#define SHARED_ENTITY_GROUNDED 1
 #pragma once
 
-#include "shared/world/voxel_registry.hh"
+#include "shared/world/voxel.hh"
 
 namespace entity
 {
@@ -12,5 +10,3 @@ struct Grounded final {
     world::VoxelMaterial surface;
 };
 } // namespace entity
-
-#endif // SHARED_ENTITY_GROUNDED
diff --git a/game/shared/game.hh b/game/shared/game.hh
index 21286e8..0dfbadb 100644
--- a/game/shared/game.hh
+++ b/game/shared/game.hh
@@ -1,5 +1,3 @@
-#ifndef SHARED_GAME
-#define SHARED_GAME 1
 #pragma once
 
 namespace shared_game
@@ -7,5 +5,3 @@ namespace shared_game
 void init(int argc, char** argv);
 void shutdown(void);
 } // namespace shared_game
-
-#endif // SHARED_GAME
diff --git a/game/shared/game_items.hh b/game/shared/game_items.hh
index 88952fc..6f8eac9 100644
--- a/game/shared/game_items.hh
+++ b/game/shared/game_items.hh
@@ -1,5 +1,3 @@
-#ifndef SHARED_GAME_ITEMS
-#define SHARED_GAME_ITEMS 1
 #pragma once
 
 namespace world
@@ -24,5 +22,3 @@ namespace game_items
 {
 void populate(void);
 } // namespace game_items
-
-#endif // SHARED_GAME_ITEMS
diff --git a/game/shared/game_voxels.cc b/game/shared/game_voxels.cc
index f262c23..51cf873 100644
--- a/game/shared/game_voxels.cc
+++ b/game/shared/game_voxels.cc
@@ -54,11 +54,21 @@ static void dirt_tick(world::Dimension* dimension, const voxel_pos& vpos)
     }
 
     if(grass_found && air_above) {
-        // Replace itself with the grass voxel
         dimension->set_voxel(game_voxels::grass, vpos);
     }
 }
 
+static void grass_tick(world::Dimension* dimension, const voxel_pos& vpos)
+{
+    auto above_vpos = vpos + voxel_pos(0, 1, 0);
+    auto above_voxel = dimension->get_voxel(above_vpos);
+
+    if(above_voxel && !above_voxel->is_surface_material<world::VMAT_GLASS>()) {
+        // Decay into dirt if something is blocking airflow
+        dimension->set_voxel(game_voxels::dirt, vpos);
+    }
+}
+
 void game_voxels::populate(void)
 {
     auto stone_builder = world::VoxelBuilder("stone");
@@ -92,6 +102,7 @@ void game_voxels::populate(void)
     grass_builder.add_face_texture(world::VFACE_TOP, "textures/voxel/grass_01.png");
     grass_builder.add_face_texture(world::VFACE_TOP, "textures/voxel/grass_02.png");
     grass_builder.set_surface_material(world::VMAT_GRASS);
+    grass_builder.set_on_tick(&grass_tick);
     grass = world::voxel_registry::register_voxel(grass_builder);
 
     auto vtest_builder = world::VoxelBuilder("vtest");
diff --git a/game/shared/game_voxels.hh b/game/shared/game_voxels.hh
index 68e599e..2211619 100644
--- a/game/shared/game_voxels.hh
+++ b/game/shared/game_voxels.hh
@@ -1,5 +1,3 @@
-#ifndef SHARED_GAME_VOXELS
-#define SHARED_GAME_VOXELS 1
 #pragma once
 
 namespace world
@@ -26,5 +24,3 @@ namespace game_voxels
 {
 void populate(void);
 } // namespace game_voxels
-
-#endif // SHARED_GAME_VOXELS
diff --git a/game/shared/world/chunk_aabb.hh b/game/shared/world/chunk_aabb.hh
index 3a2d26f..d926b55 100644
--- a/game/shared/world/chunk_aabb.hh
+++ b/game/shared/world/chunk_aabb.hh
@@ -1,5 +1,3 @@
-#ifndef SHARED_CHUNK_AABB
-#define SHARED_CHUNK_AABB 1
 #pragma once
 
 #include "core/math/aabb.hh"
@@ -10,5 +8,3 @@ namespace world
 {
 using ChunkAABB = math::AABB<chunk_pos::value_type>;
 } // namespace world
-
-#endif // SHARED_CHUNK_AABB
diff --git a/game/shared/world/ray_dda.hh b/game/shared/world/ray_dda.hh
index 3071be2..110e3d4 100644
--- a/game/shared/world/ray_dda.hh
+++ b/game/shared/world/ray_dda.hh
@@ -1,5 +1,3 @@
-#ifndef SHARED_RAY_DDA
-#define SHARED_RAY_DDA 1
 #pragma once
 
 #include "shared/types.hh"
@@ -38,5 +36,3 @@ public:
     voxel_pos vpos;
 };
 } // namespace world
-
-#endif // SHARED_RAY_DDA