Merge pull request #11637 from horizon-rust/fix/lightning-fire-radius-11376

🤖 Agent: lightning now places fire (and draws its extra-source offsets) only when canSpreadFireAround passes at the bolt, so fire_spread_radius_around_player holds for strikes far from every player.

crates/horizon-client/src/game/lightning.rs

@@ -300,7 +300,8 @@ impl Game<'_> {
         });
     }
     /// `spawnFire`: fire at the strike point and `extra` random neighbours,
-    /// wherever `BaseFireBlock.getState` fire can survive. Returns how many
+    /// wherever `BaseFireBlock.getState` fire can survive, when a player is
+    /// within the fire-spread radius. Returns how many
     /// blocks it set on fire.
     fn bolt_fire(&mut self, at: [f64; 3], extra: i32) -> i32 {
         let mut set = 0;
@@ -309,6 +310,14 @@ impl Game<'_> {
             at[1].floor() as i32,
             at[2].floor() as i32,
         ];
+        // ServerLevel.canSpreadFireAround at the bolt: no fire at all, and no
+        // draws for the extra sources, away from every player (#11376).
+        let origin = BlockPos::new(base[0], base[1], base[2]);
+        if !self.with_level(|_, level, _| {
+            horizon_world::level::LevelAccess::can_spread_fire_around(level, origin)
+        }) {
+            return 0;
+        }
         let mut spots = vec![base];
         for _ in 0..extra {
             let r = &mut self.world.random;
@@ -756,6 +765,52 @@ mod tests {
     use horizon_core::geometry::Vec3;
     use std::sync::Arc;
 
+    /// `LightningBolt.spawnFire` places nothing, and draws no extra sources,
+    /// unless `canSpreadFireAround` passes at the bolt (#11376).
+    #[test]
+    #[ignore = "needs prepared resources (HORIZON_TEST_RESOURCES)"]
+    fn a_bolt_away_from_players_starts_no_fire() {
+        use horizon_client::gamerules::Value;
+        let mut game = super::super::native_machines::tests::server_game();
+        let stone = game
+            .pack
+            .assets
+            .registry
+            .default_state("minecraft:stone")
+            .unwrap();
+        let air = game.res.facts().air;
+        game.world.set(8, 64, 8, stone).unwrap();
+        let bolt = [8.5, 65.0, 8.5];
+        // (radius, player's x): fires expected at the strike.
+        for (radius, player_x, fires) in [
+            (128, 12.5, true),
+            (1, 12.5, false),
+            (0, 8.5, false),
+            (-1, 1000.0, true),
+        ] {
+            game.world.set(8, 65, 8, air).unwrap();
+            game.ui
+                .rules
+                .set("fire_spread_radius_around_player", Value::Int(radius));
+            game.player = Some(
+                horizon_client::motion::PlayerMotion::new(
+                    game.motion,
+                    Vec3::new(player_x, 65.0, 8.5),
+                )
+                .unwrap(),
+            );
+            let random = game.world.random.clone();
+            let set = game.bolt_fire(bolt, 4);
+            let burning = game.world.block(8, 65, 8) != air;
+            assert_eq!((set > 0, burning), (fires, fires), "radius {radius}");
+            if !fires {
+                // No offset draws either.
+                let mut before = random;
+                assert_eq!(game.world.random.next_long(), before.next_long());
+            }
+        }
+    }
+
     #[test]
     fn viewer_box_reaches_15_around_and_down_and_21_up() {
         let bolt = [0.0, 64.0, 0.0];