Module batch 

Batched glyph rendering — layer-sorted, blend-mode-separated instanced draw calls.

The renderer needs to:

1. Sort all active glyphs by (RenderLayer, blend_mode) to minimize state changes
2. Pack each batch into a GlyphInstance array for the GPU
3. Issue one draw_arrays_instanced call per batch

Batch key

(RenderLayer, BlendMode) — changes in either require a new draw call. Within each batch, instances are further sorted by Z (back-to-front) for transparent geometry.

Structs

AtlasUploadTracker

Tracks which atlas pages have been uploaded this frame (avoids redundant uploads).

BatchKey

Determines which draw call a glyph belongs to.

BatchStats

Statistics from the last finish() call.

GlyphBatch

A CPU-side instance buffer for one draw call.

GlyphBatcher

Builds and sorts batches from a flat list of glyphs each frame.

GlyphInstance

Per-instance GPU data. Must match the vertex shader layout exactly.

PendingGlyph

Pending item — a glyph to be assigned to a batch.

RenderLayerOrd

Ordered wrapper for RenderLayer (to allow sorting by layer).

Enums

BlendMode

GPU blend mode for a batch.