Add explosion stage 1 PNG assets for all directions

- Added BMP_1_EXPLOSION_DOWN.png to original and preview directories.
- Added BMP_1_EXPLOSION_LEFT.png to original and preview directories.
- Added BMP_1_EXPLOSION_RIGHT.png to original and preview directories.
- Added BMP_1_EXPLOSION_UP.png to original and preview directories.

These assets are part of the explosion animation for the game, enhancing visual effects during gameplay.

rats.py

@@ -281,7 +281,6 @@ class MiceMaze(
         self.render_engine.delete_tag("unit")
         self.render_engine.delete_tag("effect")
         self.render_engine.delete_tag("cave")
-        self.render_engine.draw_pointer(self.pointer[0] * self.cell_size, self.pointer[1] * self.cell_size)
         
         # Clear collision system for new frame
         self.collision_system.clear()
@@ -333,13 +332,14 @@ class MiceMaze(
             self.unit_positions.setdefault(unit.position, []).append(unit)
             self.unit_positions_before.setdefault(unit.position_before, []).append(unit)
         
+        self.draw_cave_foreground()
+        self.render_engine.draw_pointer(self.pointer[0] * self.cell_size, self.pointer[1] * self.cell_size)
         
         # Fourth pass: check collisions and draw
         for unit in self.units.copy().values():
             unit.collisions()
             unit.draw()
 
-        self.draw_cave_foreground()
         
         self.render_engine.update_status(f"Mice: {self.count_rats()} - Points: {self.points}")
         self.refill_ammo()

tools/vernon/enhance_stage1_explosions.py

@@ -0,0 +1,74 @@
+#!/usr/bin/env python3
+import json
+import sys
+from pathlib import Path
+
+from PIL import Image
+
+
+CHROMAKEY = [128, 128, 128, 255]
+GREEN_LIGHT = [0, 255, 0, 255]
+GREEN_DARK = [0, 128, 0, 255]
+
+
+def is_green(pixel):
+    return pixel == GREEN_LIGHT or pixel == GREEN_DARK
+
+
+def is_background(pixel):
+    return pixel == CHROMAKEY or is_green(pixel)
+
+
+def cave_reference_path(sprite_name):
+    direction = sprite_name.rsplit("_", 1)[-1]
+    return Path("assets/Rat") / f"BMP_1_CAVE_{direction}.png"
+
+
+def load_cave_grid(sprite_name):
+    cave_path = cave_reference_path(sprite_name)
+    cave_image = Image.open(cave_path).convert("RGBA")
+    width, height = cave_image.size
+    pixel_access = cave_image.load()
+    return [
+        [list(pixel_access[x, y]) for x in range(width)]
+        for y in range(height)
+    ]
+
+
+def enhance_pixels(name, pixels):
+    cave_pixels = load_cave_grid(name)
+    enhanced = []
+    for y, row in enumerate(pixels):
+        enhanced_row = []
+        for x, pixel in enumerate(row):
+            if is_background(pixel):
+                enhanced_row.append(cave_pixels[y][x][:])
+            else:
+                enhanced_row.append(pixel[:])
+        enhanced.append(enhanced_row)
+    return enhanced
+
+
+def process_file(src_path, dst_path):
+    data = json.loads(src_path.read_text())
+    pixels = data["pixels"]
+    data["pixels"] = enhance_pixels(src_path.stem, pixels)
+    dst_path.write_text(json.dumps(data, indent=2))
+
+
+def main():
+    if len(sys.argv) != 3:
+        raise SystemExit("usage: enhance_stage1_explosions.py <src_dir> <dst_dir>")
+
+    src_dir = Path(sys.argv[1])
+    dst_dir = Path(sys.argv[2])
+    dst_dir.mkdir(parents=True, exist_ok=True)
+
+    for src_path in sorted(src_dir.glob("BMP_1_EXPLOSION_*.json")):
+        dst_path = dst_dir / src_path.name
+        process_file(src_path, dst_path)
+        print(f"Wrote {dst_path}")
+
+
+if __name__ == "__main__":
+    main()

units/bomb.py

@@ -44,6 +44,9 @@ class Bomb(Unit):
         x_pos = self.position_before[0] * self.game.cell_size + (self.game.cell_size - image_size[0]) // 2 + partial_x
         y_pos = self.position_before[1] * self.game.cell_size + (self.game.cell_size - image_size[1]) // 2 + partial_y
 
+        if self.is_hidden_in_tunnel(image_size):
+            return
+        
         self.game.render_engine.draw_image(x_pos, y_pos, image, anchor="nw", tag="unit")
 
 class Timer(Bomb):
@@ -132,6 +135,9 @@ class Explosion(Bomb):
         x_pos = self.position_before[0] * self.game.cell_size + (self.game.cell_size - image_size[0]) // 2 + partial_x
         y_pos = self.position_before[1] * self.game.cell_size + (self.game.cell_size - image_size[1]) // 2 + partial_y
 
+        if self.is_hidden_in_tunnel(image_size):
+            return
+        
         self.game.render_engine.draw_image(x_pos, y_pos, image, anchor="nw", tag="unit")
 
 
@@ -186,4 +192,7 @@ class NuclearBomb(Unit):
         x_pos = self.position[0] * self.game.cell_size + (self.game.cell_size - image_size[0]) // 2
         y_pos = self.position[1] * self.game.cell_size + (self.game.cell_size - image_size[1]) // 2
 
+        if self.is_hidden_in_tunnel(image_size, position=self.position):
+            return
+
         self.game.render_engine.draw_image(x_pos, y_pos, image, anchor="nw", tag="unit")

units/gas.py

@@ -79,8 +79,10 @@ class Gas(Unit):
         
         x_pos = self.position_before[0] * self.game.cell_size + (self.game.cell_size - image_size[0]) // 2 + partial_x
         y_pos = self.position_before[1] * self.game.cell_size + (self.game.cell_size - image_size[1]) // 2 + partial_y
-        self.game.render_engine.draw_image(x_pos, y_pos, image, anchor="nw", tag="unit")
+        if not self.is_hidden_in_tunnel(image_size):
+            self.game.render_engine.draw_image(x_pos, y_pos, image, anchor="nw", tag="unit")
         for cell in self.spreading_cells:
             x_pos = cell[0] * self.game.cell_size + (self.game.cell_size - image_size[0]) // 2 + partial_x
             y_pos = cell[1] * self.game.cell_size + (self.game.cell_size - image_size[1]) // 2 + partial_y
-            self.game.render_engine.draw_image(x_pos, y_pos, image, anchor="nw", tag="unit")
+            if not self.is_hidden_in_tunnel(image_size, position=cell):
+                self.game.render_engine.draw_image(x_pos, y_pos, image, anchor="nw", tag="unit")

units/mine.py

@@ -56,6 +56,9 @@ class Mine(Unit):
         x_pos = self.position[0] * self.game.cell_size + (self.game.cell_size - image_size[0]) // 2
         y_pos = self.position[1] * self.game.cell_size + (self.game.cell_size - image_size[1]) // 2
 
+        if self.is_hidden_in_tunnel(image_size, position=self.position):
+            return
+        
         self.game.render_engine.draw_image(x_pos, y_pos, image, anchor="nw", tag="unit")
         
     def die(self, score=None):

units/unit.py

@@ -67,6 +67,22 @@ class Unit(ABC):
         """Handle collisions with other units. Default implementation does nothing."""
         pass
 
+    def is_hidden_in_tunnel(self, image_size, position=None):
+        """Return True when the sprite center falls inside a tunnel cell."""
+        if position is None:
+            position = self.position_before
+
+        x_pos = position[0] * self.game.cell_size + (self.game.cell_size - image_size[0]) // 2
+        y_pos = position[1] * self.game.cell_size + (self.game.cell_size - image_size[1]) // 2
+        center_x = int(x_pos + image_size[0] / 2)
+        center_y = int(y_pos + image_size[1] / 2)
+        cell_x = center_x // self.game.cell_size
+        cell_y = center_y // self.game.cell_size
+
+        if not self.game.map.in_bounds(cell_x, cell_y):
+            return False
+        return self.game.map.is_tunnel(cell_x, cell_y)
+
     def die(self, score=None):
         """Remove unit from game and handle basic cleanup."""
         if self.id in self.game.units: