Function getOrLoadBitmap

src/hooks/useFrustumTexture.ts:116–118

* Return a cached resized bitmap for image-plane texture creation.

(_cacheKey: string, imageName: string)

 * Return a cached resized bitmap for image-plane texture creation.
 */
async function getOrLoadBitmap(_cacheKey: string, imageName: string): Promise<ImageBitmap | null> {
  return getCachedFrustumBitmap(bitmapCache, imageName);
}

/**
 * Create texture from ImageBitmap (synchronous, no async load delay).