Feature Request: Add useTexture hook for async texture loading with states

Summary

Add a useTexture React hook to provide declarative texture loading with loading/error states and lifecycle management. While a <Texture> component exists, a hook would enable better async handling, preloading, caching, and integration with loading UI patterns.

Motivation

Two.js's Texture class loads images asynchronously via callbacks. The current <Texture> component is a thin wrapper that doesn't expose loading states or errors. A dedicated hook would:

• Provide loading/loaded/error states for UI feedback
• Enable texture preloading before rendering
• Support texture caching to avoid re-loading
• Handle cleanup automatically
• Integrate with React Suspense patterns (future)
• Enable multiple texture loading patterns

Two.js Texture Background

How Two.js Texture works:

const texture = new Two.Texture(src, callback);

// Properties:
texture.loaded;  // Boolean indicating load state
texture.image;   // HTMLImageElement
texture.src;     // Source URL

// Callback invoked when loaded:
new Two.Texture('/image.jpg', (texture) => {
  console.log('Loaded!', texture);
});

Common use cases:

• Loading images for Sprite components
• Texture mapping for Image components
• Creating texture atlases
• Loading sprite sheets for ImageSequence

Proposed API

Hook Signature

interface UseTextureOptions {
  onLoad?: (texture: RefTexture) => void;
  onError?: (error: Error) => void;
  retryCount?: number;      // Auto-retry on failure
  cache?: boolean;          // Cache loaded textures (default: true)
}

interface TextureState {
  texture: RefTexture | null;
  loading: boolean;
  loaded: boolean;
  error: Error | null;
  retry: () => void;
}

function useTexture(
  src: string | HTMLImageElement | HTMLCanvasElement | HTMLVideoElement | null,
  options?: UseTextureOptions
): TextureState

Usage Examples

Basic Texture Loading

import { Canvas, Sprite, useTexture } from 'react-two.js';

function ImageSprite() {
  const { texture, loading, error } = useTexture('/images/character.png');
  
  if (loading) return <Text value="Loading..." />;
  if (error) return <Text value={`Error: ${error.message}`} />;
  if (!texture) return null;
  
  return <Sprite texture={texture} x={100} y={100} />;
}

With Loading UI

function LoadingImage() {
  const { texture, loading, loaded } = useTexture('/images/background.jpg');
  
  return (
    <>
      {loading && (
        <Group>
          <Circle radius={20} stroke="gray" linewidth={2} />
          <Text value="Loading..." y={30} />
        </Group>
      )}
      
      {loaded && texture && (
        <Image texture={texture} x={200} y={200} />
      )}
    </>
  );
}

Error Handling with Retry

function RobustImage({ src }: { src: string }) {
  const { texture, loading, error, retry } = useTexture(src, {
    retryCount: 3,
    onError: (err) => console.error('Failed to load:', err)
  });
  
  if (loading) return <Text value="Loading..." />;
  
  if (error) {
    return (
      <Group>
        <Text value="Failed to load image" />
        <Rectangle 
          y={30}
          width={100} 
          height={30} 
          fill="blue"
          onClick={() => retry()}
        />
        <Text value="Retry" y={30} />
      </Group>
    );
  }
  
  return <Sprite texture={texture!} />;
}

Preloading Multiple Textures

function MultiTextureLoader() {
  const char1 = useTexture('/sprites/char1.png');
  const char2 = useTexture('/sprites/char2.png');
  const bg = useTexture('/sprites/background.png');
  
  const allLoaded = char1.loaded && char2.loaded && bg.loaded;
  const progress = [char1, char2, bg].filter(t => t.loaded).length / 3;
  
  if (!allLoaded) {
    return (
      <Group>
        <Text value={`Loading: ${Math.round(progress * 100)}%`} />
        <Rectangle 
          width={200 * progress} 
          height={20} 
          fill="green" 
        />
      </Group>
    );
  }
  
  return (
    <>
      <Image texture={bg.texture!} />
      <Sprite texture={char1.texture!} x={100} />
      <Sprite texture={char2.texture!} x={200} />
    </>
  );
}

Cached Texture Reuse

// First component loads texture
function Component1() {
  const { texture } = useTexture('/shared-texture.png');
  return <Sprite texture={texture} x={0} />;
}

// Second component reuses cached texture (no re-download)
function Component2() {
  const { texture, loading } = useTexture('/shared-texture.png');
  // loading will be false if already cached
  return <Sprite texture={texture} x={100} />;
}

Dynamic Texture Switching

function DynamicSprite({ character }: { character: string }) {
  const src = `/characters/${character}.png`;
  const { texture, loading } = useTexture(src);
  
  // When character prop changes, hook automatically loads new texture
  
  return (
    <>
      {loading && <Circle radius={10} fill="gray" />}
      {texture && <Sprite texture={texture} x={150} y={150} />}
    </>
  );
}

Canvas/Video Sources

function CanvasTexture() {
  const canvasRef = useRef<HTMLCanvasElement>(null);
  const { texture } = useTexture(canvasRef.current);
  
  useEffect(() => {
    // Draw something on canvas
    const ctx = canvasRef.current?.getContext('2d');
    if (ctx) {
      ctx.fillStyle = 'red';
      ctx.fillRect(0, 0, 100, 100);
    }
  }, []);
  
  return (
    <>
      <canvas ref={canvasRef} width={100} height={100} style={{ display: 'none' }} />
      {texture && <Sprite texture={texture} />}
    </>
  );
}

With Callbacks

function CallbackExample() {
  const { texture } = useTexture('/image.png', {
    onLoad: (tex) => {
      console.log('Loaded:', tex.image.width, 'x', tex.image.height);
    },
    onError: (err) => {
      console.error('Load failed:', err);
    }
  });
  
  return texture ? <Sprite texture={texture} /> : null;
}

Implementation Phases

Phase 1: Core Hook Structure

Files: lib/hooks/useTexture.ts (new file)

• Create lib/hooks/useTexture.ts
• Define TypeScript interfaces:
  • UseTextureOptions
  • TextureState
  • Type for supported source types
• Implement basic hook structure:
  • useState for texture, loading, loaded, error states
  • useRef to store texture instance
  • Return object with state values
• Export hook from file

Deliverable: Hook skeleton with TypeScript types

---

Phase 2: Texture Loading Logic

Files: lib/hooks/useTexture.ts

• Implement useEffect for texture loading:
  • Create Two.Texture instance with source
  • Set loading state to true
  • Handle Two.Texture callback for load completion
  • Update loaded state when complete
  • Store texture in ref and state
• Handle different source types:
  • String URLs
  • HTMLImageElement
  • HTMLCanvasElement
  • HTMLVideoElement
  • Null/undefined sources
• Implement cleanup on unmount:
  • Clear texture reference
  • Abort pending loads if possible

Deliverable: Working texture loading with callback handling

---

Phase 3: Error Handling & Retry

Files: lib/hooks/useTexture.ts

• Add error state management:
  • Detect load failures
  • Set error state with Error object
  • Clear loading state on error
• Implement retry mechanism:
  • retry() function to retry loading
  • Track retry attempts
  • Respect retryCount option
  • Exponential backoff for retries (optional)
• Handle edge cases:
  • Invalid URLs
  • Network failures
  • CORS issues
  • Invalid image formats
• Add error callbacks:
  • Call onError option on failures

Deliverable: Robust error handling with retry capability

---

Phase 4: Caching System

Files: lib/hooks/useTexture.ts, lib/hooks/textureCache.ts (new)

• Create texture cache module:
  • Map of URL → Texture instances
  • Cache hit/miss tracking
  • Memory management (LRU or size-based)
• Implement cache integration in hook:
  • Check cache before creating new texture
  • Store loaded textures in cache
  • Return cached texture immediately (no loading state)
  • Respect cache option (default: true)
• Handle cache invalidation:
  • Clear cache on unmount (if no other refs)
  • Provide manual cache clear utility
  • Handle src changes properly
• Add cache statistics (optional):
  • Hit rate
  • Total cached textures
  • Memory usage

Deliverable: Texture caching to avoid redundant loads

---

Phase 5: Advanced Features

Files: lib/hooks/useTexture.ts

• Implement callback options:
  • onLoad callback when texture loads
  • onError callback on failure
  • Pass texture instance to callbacks
• Handle source changes:
  • Detect when src prop changes
  • Abort previous load if in progress
  • Start new load with new source
  • Reset states appropriately
• Add preload optimization:
  • Start loading immediately (don't wait for render)
  • Support preloading without rendering
• Performance optimizations:
  • Debounce rapid source changes
  • Batch texture loads (future)

Deliverable: Full-featured hook with callbacks and optimizations

---

Phase 6: Integration & Export

Files: lib/main.ts, lib/hooks/index.ts

• Export useTexture from lib/hooks/index.ts
• Export from lib/main.ts
• Export TypeScript interfaces
• Export cache utilities (optional):
  • clearTextureCache()
  • getTextureCacheStats()
• Verify tree-shaking works
• Update package exports

Deliverable: Hook available in public API

---

Phase 7: Testing

Files: lib/hooks/__tests__/useTexture.test.tsx (new file)

• Test basic texture loading:
  • Loading state transitions
  • Loaded state when complete
  • Texture instance created correctly
• Test error handling:
  • Error state on failure
  • Error callback invoked
  • Retry mechanism works
• Test caching:
  • Cache hits return immediately
  • Cache misses load texture
  • Multiple hooks share cached texture
• Test source changes:
  • New texture loads when src changes
  • Previous load aborted/cleaned up
  • States reset properly
• Test callbacks:
  • onLoad called with texture
  • onError called with error
• Test cleanup:
  • Resources freed on unmount
  • No memory leaks
• Mock Two.Texture for isolated testing
• Test with different source types

Deliverable: Comprehensive test coverage

---

Phase 8: Documentation & Examples

Files: README.md, src/App.tsx, documentation site

• Add useTexture section to main README
• Document all options and return values
• Create interactive examples:
  • Basic texture loading with spinner
  • Error handling with retry
  • Multiple texture preloading
  • Progress indicator
  • Cached texture reuse
  • Dynamic texture switching
• Document caching behavior
• Add troubleshooting section:
  • CORS issues
  • Image format support
  • Memory management
• Include performance best practices
• TypeScript usage examples
• Compare with Texture component

Deliverable: Complete documentation with examples

---

Technical Considerations

Two.js Texture Implementation

class Texture {
  constructor(src, callback) {
    this.src = src;
    this.loaded = false;
    
    if (src instanceof Image) {
      this.image = src;
      this.loaded = true;
      callback?.(this);
    } else {
      this.image = new Image();
      this.image.onload = () => {
        this.loaded = true;
        callback?.(this);
      };
      this.image.onerror = (e) => {
        // Error handling
      };
      this.image.src = src;
    }
  }
}

Design Decisions

1. Hook-based: Better for async operations than component
2. State exposure: Loading/error states for UI feedback
3. Caching built-in: Avoids redundant network requests
4. Retry mechanism: Common pattern for network failures
5. Flexible sources: Supports URLs, elements, canvas, video
6. Callback support: Integration with external loading systems
7. Memory-conscious: Automatic cleanup and cache management

Caching Strategy

Cache key: Use src string as key

• Simple and effective for URLs
• Canvas/video elements: Use object reference or unique ID
• LRU (Least Recently Used) eviction when cache full
• Configurable cache size limit

Cache invalidation:

• Remove from cache when no components reference it
• Manual clear function for development
• Weak references to avoid memory leaks

Performance Considerations

• Textures loaded asynchronously don't block rendering
• Cache prevents redundant network requests
• Multiple components can share same texture instance
• Consider lazy loading for off-screen images
• Image size affects memory usage (compress images)

Error Handling

Common errors:

• 404 Not Found: Wrong URL or missing file
• CORS: Cross-origin restrictions
• Invalid format: Unsupported image format
• Network failure: Timeout, offline, etc.

Handle gracefully:

• Clear error messages
• Retry with backoff
• Fallback textures (future)
• User feedback

Relationship with Texture Component

Texture Component:

• Declarative JSX syntax
• No loading states exposed
• Simple use cases

useTexture Hook:

• More control over loading
• Loading/error state management
• Caching and preloading
• Better for complex scenarios

Recommendation: Use hook for most cases, component for simple inline textures

Alternative Approaches Considered

1. Enhance Texture Component with Render Props:

<Texture src="/image.png">
  {({ texture, loading }) => loading ? <Loading /> : <Sprite texture={texture} />}
</Texture>

Pros: Component-based, declarative
Cons: Verbose, less flexible than hook
Decision: Hook is more versatile

2. Global Texture Manager:

const textureManager = useTextureManager();
const tex = textureManager.load('/image.png');

Pros: Centralized management
Cons: Global state, complex API
Decision: Per-component hooks are simpler

3. React Suspense Integration:

const texture = useTexture('/image.png', { suspense: true });
// Throws promise until loaded

Pros: Future-proof, idiomatic React
Cons: Requires Suspense support, experimental
Decision: Start without Suspense, add later

Resources

• Two.js Texture Documentation
• Two.js Sprite Documentation
• Two.js Image Documentation
• MDN - HTMLImageElement
• MDN - Loading Images

Success Criteria

• useTexture hook successfully loads textures from URLs
• Loading, loaded, and error states work correctly
• Error handling and retry mechanism function properly
• Texture caching prevents redundant loads
• Multiple components can share cached textures
• Dynamic source changes handled correctly
• Callbacks (onLoad, onError) invoked appropriately
• Works with string URLs and HTMLElement sources
• Cleanup on unmount prevents memory leaks
• Full TypeScript support with proper types
• Comprehensive tests with good coverage
• Documentation includes examples and API reference
• Performance equivalent to direct Two.Texture usage
• Cache management is memory-efficient
• No breaking changes to existing Texture component

---

Labels: enhancement, feature request, hooks, textures
Milestone: v0.3.0

Start with the proposed phases for lib/hooks/useTexture.ts, then review the export points in lib/hooks/index.ts and lib/main.ts. Run or add coverage in lib/hooks/tests/useTexture.test.tsx for loading, errors, retries, caching, source changes, callbacks, and cleanup. Done means the hook is publicly exported, tested, and documented in the named README and example files.