initAssets(ggl: GfxCtx):

urlPrefix: string

sprites: AssetBucket<SpriteData>

fonts: AssetBucket<FontData>

bitmapFonts: AssetBucket<GfxFont>

sounds: AssetBucket<SoundData>

shaders: AssetBucket<Shader>

custom: AssetBucket<any>

music: Record<string, string>

packer: TexPacker

loaded: boolean