From 654c038030c102971dbcb9356ba1bd65e3f36037 Mon Sep 17 00:00:00 2001
From: Axel Meyer <axel.meyer@durania.net>
Date: Sat, 9 May 2026 20:09:00 +0200
Subject: [PATCH] feat: P.0.lib.render colored-quad tile-grid renderer

---
 .gitignore   |  2 ++
 README.md    | 30 ++++++++++++++++++++++++++
 init.lua     | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 manifest.lib |  1 +
 4 files changed, 94 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 README.md
 create mode 100644 init.lua
 create mode 100644 manifest.lib

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..41ae811
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+build/
+*.log
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..3bd1f6d
--- /dev/null
+++ b/README.md
@@ -0,0 +1,30 @@
+# lib-core.render
+
+P.0 colored-quad tile-grid renderer. Reads `lib-core.maps`'s current map +
+its tilemap, iterates tiles, draws a colored rect per tile via
+`engine.render.draw_rect`. Fallback to magenta `[255, 0, 255]` for tiles
+with missing/malformed color.
+
+- Lib-ID: `lib-core.render`
+- Version: `0.1.0`
+- Spec: `meta/docs/superpowers/specs/2026-05-09-p0-lib-render-design.md`
+
+Forward-compat stubs (DEPRECATED-MVP) for texture-rendering,
+PROTOTYPE-Lib-Pattern, camera, layers, post-processing, parallax,
+shaders, hot-reload. See `meta/docs/architecture/render-pipeline.md`
+for the full target spec (941 lines).
+
+## API
+- `r_lib.draw_map(map_id?)` — iterates current (or specified) map's tiles,
+  draws colored rect per tile. Must be called inside a render hook.
+  Returns count of tiles drawn.
+
+## Consumer pattern
+```lua
+local maps  = require("lib-core.maps")
+local r_lib = require("lib-core.render")
+function render(ctx)
+    engine.render.clear_color(engine.render.rgb(20, 20, 30))
+    r_lib.draw_map()
+end
+```
diff --git a/init.lua b/init.lua
new file mode 100644
index 0000000..300806f
--- /dev/null
+++ b/init.lua
@@ -0,0 +1,61 @@
+-- =====================================================================
+-- lib-core.render — Tile-Grid Rendering (P.0)
+-- See: meta/docs/superpowers/specs/2026-05-09-p0-lib-render-design.md
+--
+-- Scope: colored-quads only. Texture-rendering, PROTOTYPE-Lib-Pattern,
+-- camera, layers, post-processing, parallax, shaders, hot-reload —
+-- alle DEPRECATED-MVP, kommen in späteren Slices.
+-- =====================================================================
+
+local maps = require("lib-core.maps")
+
+local FALLBACK_COLOR = {255, 0, 255}  -- magenta — "missing color" debug-marker
+
+-- Reads tile-color from TileType-table; fallback to magenta if missing or malformed.
+local function tile_color(tile_type)
+    local c = tile_type.color
+    if type(c) ~= "table" or #c < 3 then return FALLBACK_COLOR end
+    return c
+end
+
+local M = {}
+
+-- Iterates current (or specified) map's tiles, draws a colored rect per tile.
+-- Must be called from inside a render hook (engine.render.* enforces this).
+-- Returns the number of tiles drawn (for smoke verification + debug).
+function M.draw_map(map_id)
+    local size = maps.size(map_id)
+    local tile_size = maps.tile_size(map_id)
+    local count = 0
+    for ty = 0, size.h - 1 do
+        for tx = 0, size.w - 1 do
+            -- maps.tile_at uses arity-dispatch: 2-arg form falls back to current map,
+            -- 3-arg form requires non-nil map_id. Branch to keep both call-shapes happy.
+            local t
+            if map_id == nil then
+                t = maps.tile_at(tx, ty)
+            else
+                t = maps.tile_at(map_id, tx, ty)
+            end
+            if t ~= nil then
+                local c = tile_color(t)
+                local color = engine.render.rgb(c[1], c[2], c[3])
+                engine.render.draw_rect(
+                    tx * tile_size, ty * tile_size,
+                    tile_size, tile_size,
+                    color)
+                count = count + 1
+            end
+        end
+    end
+    return count
+end
+
+-- Forward-compat stubs for later slices (kept as comments to avoid table-pollution):
+-- DEPRECATED-MVP: function M.draw_sprites(...)        -- texture-slice
+-- DEPRECATED-MVP: function M.set_camera(camera)       -- lib-core.camera slice
+-- DEPRECATED-MVP: function M.push_layer(name, order)  -- multi-layer slice
+-- DEPRECATED-MVP: function M.register_pass(...)       -- post-processing slice (spec §6)
+-- DEPRECATED-MVP: function M.set_clear_color(rgb)     -- per-layer clear-color (spec §4)
+
+return M
diff --git a/manifest.lib b/manifest.lib
new file mode 100644
index 0000000..daf9fb8
--- /dev/null
+++ b/manifest.lib
@@ -0,0 +1 @@
+{"id":"lib-core.render","version":"0.1.0","api_min":"0.1"}