e4f9d42170
Phase A.2: draw_entities(filter) iterates composition.list_by_tag and
renders each entity per its sprite-properties. Three paths:
1. sprite_atlas + sprite_uv.{x,y,w,h} → atlas sub-rect via
engine.render.draw_sprite_transform (with texture-handle cache)
2. sprite_color + sprite_w + sprite_h → engine.render.draw_rect
3. magenta 16x16 fallback rect for entities without sprite-properties
position.x/position.y is treated as visual-CENTER for all paths.
Filter shape: {tag = "..."} — anything else is loud-error
(template-id / property-predicate filters deferred per A-Q3).
New dep: lib-core.composition v0.1.0.
draw_map (v0.1) unverändert.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
117 lines
4.1 KiB
Markdown
117 lines
4.1 KiB
Markdown
# lib-core.render
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Colored-quad tile-grid renderer + tag-driven entity-render. Reads
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`lib-core.maps`'s tilemap (v0.1: `draw_map`), and `lib-core.composition`'s
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tag-index (v0.2: `draw_entities`).
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**Version:** 0.2.0
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**Lib-ID:** lib-core.render
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**Requires:** lib-core.maps v>=0.5.7, lib-core.composition v>=0.1.0
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**Tags:** render, tiles, draw, colored-quads, entities
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## Topology
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<!-- topology:start (auto-generated; do not edit) -->
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```mermaid
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graph LR
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this["lib-core.render"]
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lib_core_maps["lib-core.maps"]
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this --> lib_core_maps
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lib_core_composition["lib-core.composition"]
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this --> lib_core_composition
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engine["engine.*"]
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this --> engine
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```
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<!-- topology:end -->
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## API
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### `render.draw_map(map_id)`
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**Syntax:** `render.draw_map(map_id: string | nil) -> integer`
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**Example:**
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```lua
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function render(ctx)
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engine.render.clear_color(engine.render.rgb(20, 20, 30))
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local n = render.draw_map() -- uses current-map
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end
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```
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**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).
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### `render.draw_entities(filter)`
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**Syntax:** `render.draw_entities({tag: string}) -> integer`
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**Example:**
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```lua
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function render_fn(ctx)
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camera.begin()
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render.draw_map()
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render.draw_entities{ tag = "renderable" }
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camera.finish()
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end
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```
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**Description:** Iterates entities tagged with `filter.tag` (via
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`composition.list_by_tag`) and renders each according to its
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sprite-properties. `position.x`/`position.y` is treated as the visual
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CENTER of the entity in all render-paths. Returns the number of
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entities drawn.
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Three sprite-property paths are tried per entity, in order:
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1. **`sprite_atlas` (string, atlas-texture-path) + `sprite_uv.{x,y,w,h}`
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(numbers)** — renders the sub-rectangle of the atlas via
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`engine.render.draw_sprite_transform`. Atlas textures are loaded
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once and cached internally on first use; no eviction.
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2. **`sprite_color` (uint32 0xRRGGBBAA) + `sprite_w` + `sprite_h`
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(numbers)** — renders a colored rect via `engine.render.draw_rect`.
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3. **None of the above** — magenta 16×16 fallback rect (debug-marker).
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Filter shape `{tag = "..."}` is the only supported form in v0.2.0;
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template-id-based or property-predicate filters are deferred (loud-error
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for malformed filters; see Phase-A Spec A-Q3).
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## Conventions
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- Colored-quads only in v0.1.0. Texture-rendering, multi-layer composition, post-processing, parallax, shaders, hot-reload all DEPRECATED-MVP.
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- World-space coords; pair with `lib-core.camera` to support panning + zoom.
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- Magenta fallback `[255, 0, 255]` is intentional: high-visibility debug-marker for malformed color-data.
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- Y-down-positive per ADR-0031.
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## Consumer pattern
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```lua
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local maps = require("lib-core.maps")
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local render = require("lib-core.render")
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local camera = require("lib-core.camera")
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function render_fn(ctx)
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engine.render.clear_color(engine.render.rgb(20, 20, 30))
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camera.begin()
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render.draw_map()
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camera.finish()
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end
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```
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## CHANGELOG
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### v0.2.0 (Phase A.2 — 2026-06-09)
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- Added `draw_entities(filter)` tag-driven entity-render. Two sprite-
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property paths (`sprite_atlas`+`sprite_uv` / `sprite_color`+`sprite_w`+
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`sprite_h`) plus magenta-fallback. `position.x`/`.y` is visual-center.
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- Atlas-texture cache (no eviction in v0.2.0).
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- New dep: `lib-core.composition` v0.1.0.
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### v0.1.0 (P.0)
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- Initial release: `draw_map` colored-quad iterator.
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## References
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- Spec v0.1.0 (P.0): `meta/docs/superpowers/specs/2026-05-09-p0-lib-render-design.md`
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- Spec v0.2.0 (Phase A): `meta/docs/superpowers/specs/2026-06-09-phase-A-inactive-entities-composition-actor-reentry-design.md`
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- Architecture: `meta/docs/architecture/render-pipeline.md`
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- ADR-0001 (engine knows verbs, libs bring nouns)
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- ADR-0031 (pixel-convention: Y-down-positive)
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- ADR-0038 (API-Doc-Convention)
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