/mobile

name: mobile
description: "Mobile optimization — tile-based GPU, ASTC textures, draw call budget (<100), thermal throttling, battery, touch input, safe areas, App Store guidelines."
alwaysApply: true
globs: ["**/*.cs"]

Mobile Optimization

GPU Architecture

Mobile GPUs use **tile-based rendering** (TBDR). Key implications:

• Overdraw is expensive — minimize transparent layers
• Alpha-tested geometry is costly (breaks early-Z)
• Keep fragment shader complexity low
• Avoid full-screen post-processing when possible

Performance Budgets

| Metric | Low-End | Mid-Range | High-End | |--------|---------|-----------|----------| | Draw calls | < 50 | < 100 | < 200 | | Triangles | < 50k | < 100k | < 200k | | Frame time | 33ms (30fps) | 16.6ms (60fps) | 16.6ms | | Texture memory | < 100MB | < 150MB | < 256MB | | Total memory | < 300MB | < 500MB | < 800MB | | Build size | < 100MB | < 200MB | < 500MB |

Texture Compression

• **ASTC** — use on both iOS and Android (best quality/size ratio)
• Max sizes: 512 for UI elements, 1024 for props, 2048 for hero characters
• Enable mipmaps for 3D objects, disable for UI sprites
• Use texture atlases to reduce draw calls

Draw Call Reduction

1. **SRP Batcher** — enabled by default in URP, ensure shader compatibility 2. **GPU Instancing** — for repeated objects (trees, rocks, enemies) 3. **Static Batching** — for non-moving environment 4. **Texture Atlasing** — combine sprite sheets 5. **Material sharing** — same material = same batch

Shader Complexity

• Limit math operations per fragment
• Avoid dependent texture reads
• Use `half` precision where possible (color, UV, normals)
• No real-time shadows on low-end (baked only)
• Avoid post-processing stack on low-end (or use simpler alternatives)

Thermal Throttling

// Adaptive Performance package
using UnityEngine.AdaptivePerformance;

private void Update()
{
    IAdaptivePerformance ap = Holder.Instance;
    if (ap != null && ap.ThermalStatus.ThermalMetrics.WarningLevel > WarningLevel.NoWarning)
    {
        // Reduce quality: lower resolution, reduce particles, cap framerate
        QualitySettings.resolutionScalingFixedDPIFactor = 0.75f;
    }
}

• Target 30fps for casual games (saves battery)
• Offer 60fps as opt-in option
• Reduce GPU load when battery < 20%
• Monitor thermal state and downscale dynamically

Touch Input

// Input System touch
[SerializeField] private float _swipeThreshold = 50f;

// Minimum tap target: 44x44 points (Apple HIG)
// Minimum tap target: 48x48 dp (Material Design)

• Tap: primary touch press+release < 0.3s
• Swipe: delta > threshold in one direction
• Pinch: two-finger distance change
• Long press: hold > 0.5s
• Drag: press + move

Safe Area

private void ApplySafeArea()
{
    Rect safeArea = Screen.safeArea;
    Vector2 anchorMin = safeArea.position;
    Vector2 anchorMax = safeArea.position + safeArea.size;

    anchorMin.x /= Screen.width;
    anchorMin.y /= Screen.height;
    anchorMax.x /= Screen.width;
    anchorMax.y /= Screen.height;

    RectTransform rect = GetComponent<RectTransform>();
    rect.anchorMin = anchorMin;
    rect.anchorMax = anchorMax;
}

Apply to the root UI panel to respect notches and rounded corners.

Audio Compression

| Type | Format | Quality | Load Type | |------|--------|---------|-----------| | Music | Vorbis | 40-60% | Streaming | | SFX (short) | ADPCM | — | Decompress On Load | | SFX (long) | Vorbis | 70% | Compressed In Memory | | UI clicks | PCM | — | Decompress On Load |

Build Size

• Strip unused code (IL2CPP stripping: High)
• Compress textures aggressively
• Use Addressables for optional/DLC content
• Remove unused packages from manifest
• Target < 100MB for initial download (App Store recommendation)