# lib-core.render

Colored-quad tile-grid renderer. Reads `lib-core.maps`'s current (or specified) map + its tilemap, iterates tiles, draws one colored rect per tile via `engine.render.draw_rect`. Fallback to magenta `[255, 0, 255]` for tiles with missing or malformed color.

**Version:** 0.1.0  
**Lib-ID:** lib-core.render  
**Requires:** lib-core.maps v>=0.1.1  
**Tags:** render, tiles, draw, colored-quads

## Topology

<!-- topology:start (auto-generated; do not edit) -->
```mermaid
graph LR
  this["lib-core.render"]
  lib_core_maps["lib-core.maps"]
  this --> lib_core_maps
  engine["engine.*"]
  this --> engine
```
<!-- topology:end -->

## API

### `render.draw_map(map_id)`
**Syntax:** `render.draw_map(map_id: string | nil) -> integer`

**Example:**
```lua
function render(ctx)
    engine.render.clear_color(engine.render.rgb(20, 20, 30))
    local n = render.draw_map()  -- uses current-map
end
```

**Description:** Iterates the tiles of the specified map (or current-map when nil), drawing one colored rect per tile at `(tx * tile_size, ty * tile_size)`. Tile color is read from the tilemap's `tile.color = {r, g, b}`; if missing or malformed, falls back to magenta as a visible "missing-color" debug-marker. Must be called from inside a render hook. Returns the number of tiles drawn (for smoke verification + debug).

## Conventions

- Colored-quads only in v0.1.0. Texture-rendering, multi-layer composition, post-processing, parallax, shaders, hot-reload all DEPRECATED-MVP.
- World-space coords; pair with `lib-core.camera` to support panning + zoom.
- Magenta fallback `[255, 0, 255]` is intentional: high-visibility debug-marker for malformed color-data.
- Y-down-positive per ADR-0031.

## Consumer pattern

```lua
local maps   = require("lib-core.maps")
local render = require("lib-core.render")
local camera = require("lib-core.camera")

function render_fn(ctx)
    engine.render.clear_color(engine.render.rgb(20, 20, 30))
    camera.begin()
    render.draw_map()
    camera.finish()
end
```

## CHANGELOG

### v0.1.0 (P.0)
- Initial release: `draw_map` colored-quad iterator.

## References

- Spec v0.1.0 (P.0): `meta/docs/superpowers/specs/2026-05-09-p0-lib-render-design.md`
- Architecture: `meta/docs/architecture/render-pipeline.md`
- ADR-0001 (engine knows verbs, libs bring nouns)
- ADR-0031 (pixel-convention: Y-down-positive)
- ADR-0038 (API-Doc-Convention)