Space Invaders Example

Classic Space Invaders arcade game: alien formation with synchronized movement, player ship with shooting mechanics, bunkers for protection, enemy projectiles, score system, and procedural audio through the engine AudioEngine.

Requirements (build flags)

• PIXELROOT32_ENABLE_AUDIO=1 — set in lib/platformio.ini base template so all environments inherit it.
• PIXELROOT32_ENABLE_PHYSICS=1 — required for projectile collision detection.

Display size is 240×240 in the project platformio.ini (see PHYSICAL_DISPLAY_*).

Platforms

Environment	Display	Audio backend
native	SDL2, 240×240	SDL2_AudioBackend in src/platforms/native.h
esp32dev	ST7789 240×240	Default: ESP32_I2S_AudioBackend (comment in esp32_dev.h documents optional internal DAC backend instead)

Pin choices for I2S / DAC are in src/platforms/esp32_dev.h (edit there if your wiring differs).

Controls

• Arrow keys (or GPIO D-pad mapped in your platform input config) to move left/right.
• Space to fire (max 4 simultaneous bullets with 150ms cooldown).
• Destroy all aliens to win; if aliens reach the player's level, game over.

How audio is triggered

SpaceInvadersScene.cpp builds pixelroot32::audio::AudioEvent values (player shoot, enemy shoot, explosion, BGM tempo changes) and calls engine.getAudioEngine().playEvent(...). Wave types (pulse, triangle) are lightweight beeps suited for embedded output.

Features

• Scene with pooled ProjectileActor, AlienActor, BunkerActor, PlayerActor
• 4-player bullet limit with fire rate cooldown (150ms)
• Alien formation with step-based movement and tempo-based BGM
• Audio subsystem integration (AudioEngine, platform backends)

Documentation links

• Audio API
• Core API
• Input API

Build

From examples/space_invaders:

pio run -e native
pio run -e esp32dev

Upload (ESP32)

pio run -e esp32dev --target upload