name: platform-building
description: Platform-specific building systems for mobile, VR, and accessibility. Use when implementing touch controls for building games, VR spatial input, colorblind-friendly feedback, or cross-platform building mechanics. Covers input adaptation and inclusive design patterns.

Platform Building

Touch controls, VR input, and accessibility patterns for building systems.

Quick Start

import { TouchBuildController } from './scripts/touch-build-controller.js';
import { VRBuildingAdapter } from './scripts/vr-building-adapter.js';
import { AccessibilityConfig } from './scripts/accessibility-config.js';

// Mobile touch building
const touch = new TouchBuildController(canvas, {
  doubleTapToPlace: true,
  pinchToRotate: true,
  swipeToChangePiece: true
});

touch.onPlace = (position, rotation) => buildingSystem.place(position, rotation);
touch.onRotate = (angle) => ghost.rotate(angle);

// VR building with hand tracking
const vr = new VRBuildingAdapter(xrSession, {
  dominantHand: 'right',
  snapToGrid: true,
  comfortMode: true // Reduces motion sickness
});

vr.onGrab = (piece) => selection.select(piece);
vr.onRelease = (position) => buildingSystem.place(position);

// Accessibility configuration
const a11y = new AccessibilityConfig({
  colorblindMode: 'deuteranopia', // red-green
  highContrast: true,
  screenReaderHints: true
});

// Apply to ghost preview
ghost.setColors(a11y.getValidityColors());

Reference

See references/platform-considerations.md for:
- Mobile gesture patterns (Fortnite Mobile, Minecraft PE)
- VR building research and comfort guidelines
- Colorblind palette recommendations
- Screen reader integration patterns
- Cross-platform input abstraction

Scripts

Platform Detection

// Detect platform capabilities
const platform = {
  isMobile: /Android|iPhone|iPad|iPod/i.test(navigator.userAgent),
  isTouch: 'ontouchstart' in window,
  isVR: navigator.xr !== undefined,
  prefersReducedMotion: window.matchMedia('(prefers-reduced-motion: reduce)').matches,
  prefersHighContrast: window.matchMedia('(prefers-contrast: more)').matches
};

// Initialize appropriate controllers
if (platform.isVR && xrSession) {
  setupVRControls();
} else if (platform.isTouch) {
  setupTouchControls();
} else {
  setupMouseKeyboard();
}

Mobile Considerations

Fortnite Mobile demonstrates effective touch building with customizable HUD, auto-material selection, and gesture-based piece rotation. Key patterns include dedicated build mode toggle, large touch targets (minimum 44px), and visual feedback for all actions.

VR Considerations

VR building requires attention to comfort. Snap rotation reduces motion sickness, and arm-length building distances prevent fatigue. Hand tracking enables intuitive grab-and-place, while controller building benefits from laser-pointer selection for distant pieces.

Accessibility Patterns

Valheim uses blue/yellow instead of green/red for stability indicators, supporting deuteranopia (the most common colorblind condition). High contrast modes should use 7:1 ratio for critical indicators, and all visual feedback should have audio/haptic alternatives.