The bitmap package loads a bitmap font from an image using a descriptor file. A bitmap font is a font with glyphs that is literally bitmapped, with a transparent pixel being `0`, and any opaque pixel being `1`. A descriptor file describes the size (width, height) of each glyph. It is a JSON file, the same name as the font itself. An example: the font is `fnt.png`, the descriptor will be `fnt.json`, and would look like: ` [ `