From 819c7899b3452a405bac6300fe44460ca9e5dcd6 Mon Sep 17 00:00:00 2001
From: 3gg <3gg@shellblade.net>
Date: Sun, 7 Sep 2025 10:55:19 -0700
Subject: Add support for multiple layers.

---
 src/gfx2d.c | 36 ++++++++++++++++++++++++------------
 1 file changed, 24 insertions(+), 12 deletions(-)

(limited to 'src')

diff --git a/src/gfx2d.c b/src/gfx2d.c
index 1c8b06f..eaed2b8 100644
--- a/src/gfx2d.c
+++ b/src/gfx2d.c
@@ -26,6 +26,9 @@
 /// Take the minimum of two values.
 #define min(a, b) ((a) < (b) ? (a) : (b))
 
+/// The 0-tile denotes "no tile". The renderer skips drawing 0-tiles.
+static const Tile NoTile = 0;
+
 typedef struct ivec2 {
   int x, y;
 } ivec2;
@@ -606,6 +609,10 @@ static void draw_tile_ortho(Gfx2d* gfx, Tile tile, int x, int y) {
   assert(x < gfx->map->world_width);
   assert(y < gfx->map->world_height);
 
+  if (tile == NoTile) {
+    return;
+  }
+
   const Ts_Tile* pTile  = ts_tileset_get_tile(gfx->tileset, tile);
   const Pixel*   pixels = ts_tileset_get_tile_pixels(gfx->tileset, tile);
 
@@ -626,6 +633,10 @@ static void draw_tile_iso(Gfx2d* gfx, Tile tile, int iso_x, int iso_y) {
   assert(iso_x < gfx->map->world_width);
   assert(iso_y < gfx->map->world_height);
 
+  if (tile == NoTile) {
+    return;
+  }
+
   const Ts_Tile* pTile  = ts_tileset_get_tile(gfx->tileset, tile);
   const Pixel*   pixels = ts_tileset_get_tile_pixels(gfx->tileset, tile);
 
@@ -677,18 +688,19 @@ static void draw_map_iso(Gfx2d* gfx) {
   assert(gfx);
   assert(gfx->map);
 
-  // TODO: Support for multiple layers.
-  const Tm_Layer* layer = tm_map_get_layer(gfx->map, 0);
-
-  // TODO: Culling.
-  //  Ex: map the screen corners to tile space to cull.
-  //  Ex: walk in screen space and fetch the tile.
-  //  The tile-centric approach might be more cache-friendly since the
-  //  screen-centric approach would juggle multiple tiles throughout the scan.
-  for (int wy = 0; wy < gfx->map->world_height; ++wy) {
-    for (int wx = 0; wx < gfx->map->world_width; ++wx) {
-      const Tile tile = tm_layer_get_tile(gfx->map, layer, wx, wy);
-      draw_tile_iso(gfx, tile, wx, wy);
+  for (uint16_t l = 0; l < gfx->map->num_layers; ++l) {
+    const Tm_Layer* layer = tm_map_get_layer(gfx->map, l);
+
+    // TODO: Culling.
+    //  Ex: map the screen corners to tile space to cull.
+    //  Ex: walk in screen space and fetch the tile.
+    //  The tile-centric approach might be more cache-friendly since the
+    //  screen-centric approach would juggle multiple tiles throughout the scan.
+    for (int wy = 0; wy < gfx->map->world_height; ++wy) {
+      for (int wx = 0; wx < gfx->map->world_width; ++wx) {
+        const Tile tile = tm_layer_get_tile(gfx->map, layer, wx, wy);
+        draw_tile_iso(gfx, tile, wx, wy);
+      }
     }
   }
 }
-- 
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