Platform: Mobile

Touch-first input, safe area handling, and battery optimization define mobile development.

NEVER Do (Expert Mobile Rules)

Input & Display

• NEVER use mouse events for touch interaction — Relying on InputEventMouseButton on mobile is unreliable. Always use InputEventScreenTouch and InputEventScreenDrag for high-fidelity multi-touch support.
• NEVER ignore display safe areas (notches/cutouts) — UI placed behind a camera notch is unusable. Query DisplayServer.get_display_safe_area() and offset critical UI accordingly.
• NEVER assume fixed orientation — Locking a landscape game without handling the size_changed signal leads to broken layouts on foldable devices or tablet orientation shifts.

Battery & Performance

• NEVER maintain high framerate when backgrounded — Keeping an app at 60 FPS in the background drains battery. Use NOTIFICATION_APPLICATION_PAUSED to drop Engine.max_fps to 1.
• NEVER use the Forward+ renderer for mobile — Most mobile GPUs are not optimized for Forward+. Use the dedicated Mobile or Compatibility renderers for optimal fill-rate.
• NEVER leave 'ETC2/ASTC' texture compression disabled — Uncompressed desktop textures will crash mobile devices due to VRAM exhaustion.

Permissions & OS Integration

• NEVER assume Android permissions are automatically granted — You MUST explicitly call OS.request_permission() and verify with OS.get_granted_permissions().
• NEVER call handheld vibration without permission — On Android, vibration calls are ignored unless the VIBRATE permission is enabled in the export preset.
• NEVER block the main thread for I/O — Large file saves on mobile can trigger ANR (Application Not Responding) errors. Use background threads.

---

Available Scripts

MANDATORY: Read the appropriate script before implementing the corresponding pattern.

mobile_gesture_recognizer.gd

Expert multi-touch logic for pinch-to-zoom and two-finger rotation.

adaptive_safe_area_inset.gd

Dynamic safe-area (notch) handling using DisplayServer insets.

thermal_throttle_monitor.gd

Battery and heat management via NOTIFICATION_APPLICATION_PAUSED.

mobile_iap_flow_boilerplate.gd

Unified boilerplate for Android/iOS In-App Purchases (IAP).

haptic_pattern_generator.gd

Advanced vibration patterns for mobile haptic feedback.

android_runtime_permissions.gd

Expert Android permission requesting and verification logic.

mobile_sensor_fusion.gd

Stable motion controls using Accelerometer and Gravity fusion.

orientation_layout_adaptor.gd

Adaptive UI swapping for Landscape/Portrait transitions.

mobile_vram_optimizer.gd

VRAM monitoring and texture compression enforcement rules.

native_share_invoker.gd

OS-level native share sheet integration for social features.

---

# Replace mouse/keyboard with touch
func _input(event: InputEvent) -> void:
    if event is InputEventScreenTouch:
        if event.pressed:
            on_touch_start(event.position)
        else:
            on_touch_end(event.position)
    
    elif event is InputEventScreenDrag:
        on_touch_drag(event.position, event.relative)

Virtual Joystick

# virtual_joystick.gd
extends Control

signal joystick_moved(direction: Vector2)

var is_pressed := false
var center: Vector2
var touch_index := -1

func _gui_input(event: InputEvent) -> void:
    if event is InputEventScreenTouch:
        if event.pressed:
            is_pressed = true
            center = event.position
            touch_index = event.index
        elif event.index == touch_index:
            is_pressed = false
            joystick_moved.emit(Vector2.ZERO)
    
    elif event is InputEventScreenDrag and event.index == touch_index:
        var direction := (event.position - center).normalized()
        joystick_moved.emit(direction)

Responsive UI

# Adapt to screen size
func _ready() -> void:
    get_viewport().size_changed.connect(_on_viewport_resized)
    _on_viewport_resized()

func _on_viewport_resized() -> void:
    var viewport_size := get_viewport().get_visible_rect().size
    var aspect := viewport_size.x / viewport_size.y
    
    if aspect < 1.5:  # Tall screen
        $UI.layout_mode = VBoxContainer.LAYOUT_MODE_VERTICAL
    else:  # Wide screen
        $UI.layout_mode = HBoxContainer.LAYOUT_MODE_HORIZONTAL

Battery Optimization

# Lower frame rate when inactive
func _notification(what: int) -> void:
    match what:
        NOTIFICATION_APPLICATION_FOCUS_OUT:
            Engine.max_fps = 30
        NOTIFICATION_APPLICATION_FOCUS_IN:
            Engine.max_fps = 60

Safe Areas (Notches)

func apply_safe_area() -> void:
    var safe_area := DisplayServer.get_display_safe_area()
    
    # Adjust UI margins
    $UI.offset_top = safe_area.position.y
    $UI.offset_left = safe_area.position.x

Performance Settings

# project.godot mobile settings
[rendering]
renderer/rendering_method="mobile"
textures/vram_compression/import_etc2_astc=true

[display]
window/handheld/orientation="landscape"

App Store Metadata

• Icons: 512x512 (Android), 1024x1024 (iOS)
• Screenshots: Multiple resolutions
• Privacy policy required
• Age rating

Best Practices

1. Touch-First - Design for fingers, not mouse
2. Performance - Target 60 FPS on mid-range
3. Battery - Reduce FPS when backgrounded
4. Permissions - Request only what you need

Reference

• Related: godot-export-builds, godot-ui-containers

Related

• Master Skill: godot-master