Burn blocks in place with a fire overlay

.github/workflows/tests.yml

@@ -68,6 +68,8 @@ jobs:
             tools/input_rebind_verify.gd \
             tools/photo_mode_verify.gd \
             tools/player_target_verify.tscn \
+            tools/explosives_verify.tscn \
+            tools/fire_verify.tscn \
             tools/worldgen_cactus_verify.gd \
             tools/worldgen_tree_verify.gd \
             tools/worldgen_cave_verify.gd \

AGENTS.md

@@ -35,6 +35,7 @@ RedotCraft: a Minecraft-like voxel sandbox built with **Redot Engine** (Godot 4
   - IDs are stored in `PackedByteArray`, so stay under 256. `TEXTURE_TINTS` applies per-texture tinting (grass, leaves, sand, ...).
   - Cutout blocks (leaves, glass, torch) are antialiased with `alpha_to_coverage`, so their edge quality depends on MSAA being enabled.
 - Water: `BLOCK_WATER` (16) is a source; IDs 28-34 are flowing levels 7..1, resolved through `BlockRegistry.is_water_id()`/`water_level()`/`water_id_for_level()`. `VoxelWorld` runs a 4 Hz cellular flow tick (`_water_tick`, 1024 cells/tick) seeded by breaks/places near water; flow replaces only air or weaker flowing water, falls when the cell below is air, and dries when unfed. Every change goes through `_record_edit()`, so the settled state is reapplied on chunk regeneration; `_edited_blocks` is mirrored into `_edits_by_chunk` so job snapshots and `TerrainGenerator.generate_data()` only see the chunk's own edits. Meshes are non-opaque, non-breakable, no collision and get the same `ARRAY_CUSTOM0` light attribute as blocks; flowing surfaces render at `_water_top(level)` and set vertex-color alpha so `water.gdshader` can calm the waves. `water.gdshader` samples `hint_screen_texture` for screen-space refraction (wave-distorted background with a faint chromatic split, carried through `EMISSION` so the refracted scene is not lit twice), `hint_depth_texture` for shore blending (shallow water is lighter, more transparent, and foams at the edge), and block light for warm glow.
+- Fire: burning a block never replaces it. A `BlockRegistry.FLAG_FLAMMABLE` log/leaf/dry plant/mushroom enters the `_burning` state for `FUEL_BURN_TICKS` with its texture and collision intact, and `FireOverlay` (`world/fire_overlay.gd` + `fire_overlay.gdshader`/`smoke_overlay.gdshader`) clusters flame and smoke billboards on it — one MultiMesh per effect, animated entirely in-shader from per-instance phase/progress and rebuilt only on the 4 Hz `VoxelWorld._fire_tick`. Burning blocks crawl into flammable neighbours one at a time, paced by a per-block `FIRE_IGNITION_DELAY_TICKS` (4), `FIRE_SPREAD_PER_TICK` (1) on every `FIRE_SPREAD_PERIOD_TICKS` (2), plus a per-cell `FIRE_SPREAD_INTERVAL_TICKS` cooldown (~2 blocks/s), and can chain-detonate adjacent TNT/nukes. When the timer expires the block crumbles to air and that edit goes through `_record_edit()`, so the settled result survives chunk regeneration (mid-burn state does not persist). `BLOCK_FIRE` (70) is only the standalone cutout cross flame that flint-and-steel leaves on a non-flammable face (`FLAG_CUTOUT | FLAG_CROSS | FLAG_EMISSIVE`, animated by `block.gdshader`); it decays when starved/unsupported and can catch adjacent fuel. `use_flint_and_steel()` detonates an explosive, starts the clicked flammable block burning, or lights the clicked face. `tools/fire_verify.tscn` covers the lot.
 - Underwater biomes: `OCEAN`/`DEEP_OCEAN` are split with `KELP_FOREST`, `SEAGRASS_MEADOW`, `CORAL_REEF`, `FROZEN_OCEAN` (BiomeCatalog IDs 15-18), chosen in `TerrainSampler._underwater_biome()` from depth, temperature, and patch noise; `TerrainSampler._ocean_floor_at()` shapes the shelf, slope, and abyss. `VoxelPopulator._decorate_underwater()` grows seabed plants from `DecorationCatalog._underwater_sets` (new blocks 52-58: coral substrate, seagrass, kelp, coral fan/branch, sponge, anemone) and only replaces water; the water mesh culls faces against `FLAG_CROSS` plants and `get_water_ambience()` treats a camera inside one as submerged, so foliage does not sit in glassy air pockets. `VoxelWorld.get_water_ambience()` + `Main._update_underwater()` grade the overlay, `DayNightCycle.set_underwater()` the fog/light/caustics global, and `AudioManager.set_underwater()` a Master low-pass; keep their throttled world queries out of per-frame hot paths.
 
 ## Weather / atmosphere
@@ -88,6 +89,7 @@ RedotCraft: a Minecraft-like voxel sandbox built with **Redot Engine** (Godot 4
 - `redot --headless --path . res://tools/player_target_verify.tscn` is scene-based because autoload identifiers are unavailable to `--script` harnesses; use a `.tscn` whenever a test references `GameConfig`/`AudioManager`.
 - `redot --headless --path . res://tools/explosives_verify.tscn` checks flint-and-steel activation, TNT/nuke radii, spherical edit persistence, unbreakable blocks, and item-only placement rejection.
 - `redot --path . res://tools/shadow_proxy_measure.tscn` needs a rendering display: it loads the real scene with a flat canopy, sweeps the sun, and prints the shadow-edge temporal MAD for the leaf shadow proxy off/off-control/on with and without TAA.
+- `redot --headless --path . res://tools/fire_verify.tscn` checks flammability flags, fire ignition/spread/decay, chain detonation of explosives, the flint-and-steel face-light path, persistence reseeding, and the fire shader wiring. Scene-based for the same class_name reason as above.
 - `tools/icon_check.gd` needs a rendering display and fails headless.
 - Benchmarks: `worldgen_benchmark.gd`, `worldgen_mesh_benchmark.gd`, and `worldgen_stream_benchmark.gd` (the last is minutes long at 32 chunks).
 

ROADMAP.md

@@ -177,7 +177,7 @@ Current state: the TerraForged-inspired staged pipeline is live under `world/wor
 ## World / simulation
 - [x] Water polish — flowing water levels (IDs 28-34) with a 4 Hz cellular spill/dry sim seeded by edits, falling cascades, settled state persisted through `_edited_blocks`; the mesher renders `_water_top(level)` surfaces with a flowing vertex-color flag. `water.gdshader` uses sharp, gently distorted scene refraction with chromatic split disabled, progressive depth absorption, and faint narrow shore foam.
 - [ ] Block physics — gravity blocks (falling sand/gravel) and other environment reactions that must persist through saving
-- [ ] Fire, TNT, and explosions — fire spread/decay, ignitable blocks, and explosion destruction routed through `_record_edit()` so settled state survives chunk regeneration
+- [x] Fire, TNT, and explosions — TNT (5-block radius) and nuke (18-block radius) destruction already routes through `VoxelWorld.carve_sphere()`/`_record_edit()`. Burning works in three states and never swaps the block for fire: a `BlockRegistry.FLAG_FLAMMABLE` log/leaf/plant/mushroom enters `_burning` for `FUEL_BURN_TICKS` with its texture and collision intact while `FireOverlay` (`world/fire_overlay.gd` + `fire_overlay.gdshader`/`smoke_overlay.gdshader`, one MultiMesh per effect) draws animated flame and smoke billboards over it; it crawls into flammable neighbours one at a time, paced by a per-block `FIRE_IGNITION_DELAY_TICKS` (4), `FIRE_SPREAD_PER_TICK` (1) on `FIRE_SPREAD_PERIOD_TICKS` (2) and a per-cell `FIRE_SPREAD_INTERVAL_TICKS` cooldown (~2 blocks/s), and can chain-detonate adjacent TNT/nukes; when the timer expires the block crumbles to air and that edit goes through `_record_edit()`. `BLOCK_FIRE` (70) is only the standalone cross flame flint-and-steel leaves on a non-flammable face (`assets/placeholders/fire/fire.png` via `tools/gen_fire_texture.gd`; smoke puff likewise), decaying when starved/unsupported; `_seed_fire_edits()` re-arms persisted flames on commit. Flint and steel (`use_flint_and_steel()`) detonates an explosive, starts the clicked flammable block burning, or lights the clicked face. `tools/fire_verify.tscn` covers flammability, burn-in-place, spread, decay, chain detonation, flint and steel, persistence reseeding, and the shader wiring
 - [ ] Buckets and fluid sources — water/lava buckets and source rules on top of the flowing levels 28-34 and `_water_tick`, plus lava/water interaction
 - [ ] Growth and decay — grass spread, leaf decay, sapling growth, and crop farming
 - [ ] Ambient life (deferred until the world-detail passes land) — fireflies at night, butterflies/birds by day, and subtle particle life with per-biome density and time-of-day gating; fireflies can reuse the emissive block-light path for glow

assets/placeholders/fire/README.md

@@ -0,0 +1,11 @@
+# Fire placeholder textures
+
+`fire.png` (a 64 px transparent flame sheet) and `smoke.png` (a soft grey puff)
+are generated specifically for RedotCraft by `tools/gen_fire_texture.gd` from a
+fixed RNG seed. They contain no third-party artwork and are safe to redistribute
+with the repository.
+
+`fire.png` is the standalone `BLOCK_FIRE` cross flame, which `world/block.gdshader`
+scrolls and warps on the fire layer. `smoke.png` is sampled by
+`world/smoke_overlay.gdshader` for the burning-block smoke billboards; the flame
+billboards use `fire.png` through `world/fire_overlay.gdshader`.

assets/placeholders/fire/fire.png.import

@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://bmmyojifiaj0i"
+path="res://.godot/imported/fire.png-21315587809dcbb752fb58ffa6332c60.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/placeholders/fire/fire.png"
+dest_files=["res://.godot/imported/fire.png-21315587809dcbb752fb58ffa6332c60.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1

assets/placeholders/fire/smoke.png.import

@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://dw68i0bvxmwsv"
+path="res://.godot/imported/smoke.png-49c8e5f32d90e33d8741bcbc95d5eba7.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/placeholders/fire/smoke.png"
+dest_files=["res://.godot/imported/smoke.png-49c8e5f32d90e33d8741bcbc95d5eba7.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1

game/main.gd

@@ -724,10 +724,18 @@ func _on_block_placed(block_id: int) -> void:
 func _on_item_used(item_id: int, block_position: Vector3i) -> void:
 	if item_id != ItemRegistry.ITEM_FLINT_AND_STEEL:
 		return
-	var result := world.trigger_explosive(block_position)
+	var result := world.use_flint_and_steel(block_position, player.target_normal)
 	if result.is_empty():
-		set_status("Flint and steel only ignites TNT or a nuke")
+		set_status("Flint and steel needs a solid face to light")
 		return
+	if result.has("blocked"):
+		set_status("Too wet to light" if result["blocked"] == "wet" else "Already burning")
+		return
+	if int(result.get("ignited", 0)) > 0:
+		AudioManager.play_block_place(BlockRegistry.BLOCK_FIRE, Vector3(block_position) + Vector3(0.5, 0.5, 0.5))
+		set_status("Lit fire")
+		return
+	AudioManager.play_block_break(BlockRegistry.BLOCK_TNT, Vector3(block_position) + Vector3(0.5, 0.5, 0.5))
 	set_status("Detonated %s · carved %d blocks" % [result["name"], result["removed"]])