Packs same-ish-height rectangles left-to-right into shelves of a fixed-width atlas, growing the height as needed. Simple and good enough for a one-shot glyph set (not online repacking).
Readonly
Total height used (next power-of-two-friendly value is the caller's call).
Reserves a w×h cell, returning its top-left. Advances shelves as rows fill.
w
h
Packs same-ish-height rectangles left-to-right into shelves of a fixed-width atlas, growing the height as needed. Simple and good enough for a one-shot glyph set (not online repacking).