From a0a68b7b3a5430fea5aaa2ad1da75fdda5cd5c7a Mon Sep 17 00:00:00 2001
From: Fabrice <fabrice@schaub-dev.xyz>
Date: Wed, 11 Feb 2026 22:50:21 +0100
Subject: packing corrections

---
 src/rendering.cc | 28 ++++++++++++++++++++++++++++
 src/rendering.h  | 12 ++++++++++++
 src/text.cc      | 17 +++++++++--------
 src/text.h       |  3 ++-
 src/utils.h      |  5 +++++
 5 files changed, 56 insertions(+), 9 deletions(-)

diff --git a/src/rendering.cc b/src/rendering.cc
index 89a64ac..65a89b1 100644
--- a/src/rendering.cc
+++ b/src/rendering.cc
@@ -4,6 +4,7 @@
 
 #include <cstring>
 
+#include "cglm/types.h"
 #include "utils.h"
 
 bool wayc_image_init(texture_t* texture, image_type_e type,
@@ -126,3 +127,30 @@ void wayc_atlas_deinit(atlas_s* atlas) {
   wayc_sampler_deinit(&atlas->sampler);
   wayc_image_deinit(&atlas->texture);
 }
+
+static inline void wayc_atlas_packer_wrap(struct atlas_packer_s* packer) {
+  WAYC_X(packer->cursor) = 0;
+  WAYC_Y(packer->cursor) += packer->row_height;
+  packer->row_height = 0;
+}
+
+bool wayc_atlas_packer_allocate(struct atlas_packer_s* packer, u32 width,
+                                u32 height, ivec2 out) {
+  wayc_notnull(packer);
+
+  struct atlas_s* atlas = packer->atlas;
+  wayc_notnull(atlas);
+
+  if (width > atlas->width || height > atlas->height) return false;
+
+  if (WAYC_X(packer->cursor) + width > atlas->width)
+    wayc_atlas_packer_wrap(packer);
+
+  if (WAYC_Y(packer->cursor) + height > atlas->height) return false;
+
+  glm_ivec2_copy(packer->cursor, out);
+  WAYC_X(packer->cursor) += width;
+  packer->row_height = wayc_max(packer->row_height, height);
+
+  return true;
+}
\ No newline at end of file
diff --git a/src/rendering.h b/src/rendering.h
index 98f70ce..f8db68e 100644
--- a/src/rendering.h
+++ b/src/rendering.h
@@ -67,3 +67,15 @@ void wayc_atlas_use(atlas_s* atlas, u32 slot);
 bool wayc_atlas_set(atlas_s* atlas, image_data_type_e data_type, ivec2 offset,
                     u32 width, u32 height, i32 alignment, const u8* data);
 void wayc_atlas_deinit(atlas_s* atlas);
+
+struct atlas_packer_s {
+  struct atlas_s* atlas;
+  u32 row_height;
+  ivec2 cursor;
+};
+
+#define WAYC_ATLAS_PACKER_INIT(atlas) \
+  atlas_packer_s { atlas, 0, {0, 0} }
+
+bool wayc_atlas_packer_allocate(struct atlas_packer_s* packer, u32 width,
+                                u32 height, ivec2 out);
diff --git a/src/text.cc b/src/text.cc
index 2bfc7a3..d02cc77 100644
--- a/src/text.cc
+++ b/src/text.cc
@@ -5,7 +5,7 @@
 #include <unistd.h>
 #include <utils.h>
 
-#include "cglm/ivec2.h"
+#include "cglm/types.h"
 #include "freetype/freetype.h"
 #include "hash.h"
 #include "rendering.h"
@@ -72,13 +72,13 @@ enum font_error_e wayc_font_init(struct font_s* font,
 
   font->data = data;
   wayc_hashmap_init(&font->cache);
-  glm_ivec2_zero(font->cursor);
 
   success = true;
   return FONT_ERROR_NONE;
 }
 
 enum font_error_e wayc_font_lookup(struct font_s* font, struct atlas_s* atlas,
+                                   struct atlas_packer_s* packer,
                                    codepoint_t codepoint, struct glyph_s* out) {
   wayc_notnull(font);
   wayc_notnull(atlas);
@@ -100,20 +100,21 @@ enum font_error_e wayc_font_lookup(struct font_s* font, struct atlas_s* atlas,
   if (bitmap.pitch != (i32)bitmap.width) wayc_panic("unsupported pitch");
 
   ivec2 size = {(i32)bitmap.width, (i32)bitmap.rows};
+  ivec2 uv0;
 
-  wayc_atlas_set(atlas, IMAGE_DATA_TYPE_UNSIGNED_BYTE, font->cursor, size[0],
-                 size[1], IMAGE_FORMAT_RED_ALIGNMENT, bitmap.buffer);
+  bool ok = wayc_atlas_packer_allocate(packer, WAYC_X(size), WAYC_Y(size), uv0);
+  if (!ok) return FONT_ERROR_ATLAS_FULL;
+
+  ok = wayc_atlas_set(atlas, IMAGE_DATA_TYPE_UNSIGNED_BYTE, uv0, WAYC_X(size),
+                      WAYC_Y(size), IMAGE_FORMAT_RED_ALIGNMENT, bitmap.buffer);
+  if (!ok) return FONT_ERROR_ATLAS_FULL;
 
   struct glyph_s glyph = {};
   glyph.bearing_x = slot->bitmap_left;
   glyph.bearing_y = slot->bitmap_top;
   glyph.advance = (f32)slot->advance.x / WAYC_SCALE;
 
-  glm_ivec2(font->cursor, glyph.uv0);
-  glm_ivec2_add(glyph.uv0, size, glyph.uv1);
-
   wayc_font_cache_insert(font, codepoint, glyph);
-  glm_ivec2_add(font->cursor, size, font->cursor);
 
   *out = glyph;
   return FONT_ERROR_NONE;
diff --git a/src/text.h b/src/text.h
index a04fa99..73b4e03 100644
--- a/src/text.h
+++ b/src/text.h
@@ -32,18 +32,19 @@ enum font_error_e {
   FONT_ERROR_FILE_LOAD,
   FONT_ERROR_FONT_LOAD,
   FONT_ERROR_NOT_MATCH,
+  FONT_ERROR_ATLAS_FULL,
 };
 
 struct font_s {
   u8* data;
   FT_Face face;
   struct hashmap_s<codepoint_t, struct glyph_s> cache;
-  ivec2 cursor;
 };
 
 enum font_error_e wayc_font_init(struct font_s* font,
                                  struct font_context_s* ctx, u32 fsize,
                                  const char* path);
 enum font_error_e wayc_font_lookup(struct font_s* font, struct atlas_s* atlas,
+                                   struct atlas_packer_s* packer,
                                    codepoint_t codepoint, struct glyph_s* out);
 void wayc_font_deinit(struct font_s* font);
diff --git a/src/utils.h b/src/utils.h
index 10bdd88..00be767 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -74,6 +74,11 @@ static inline u32 wayc_min(u32 a, u32 b) { return a > b ? a : b; }
 #define WAYC_FRAC_BITS 6
 #define WAYC_SCALE (1 << WAYC_FRAC_BITS)
 
+#define WAYC_X(v) ((v)[0])
+#define WAYC_Y(v) ((v)[1])
+
+static inline usize wayc_max(usize a, usize b) { return a > b ? a : b; }
+
 template <typename A, typename B>
 struct is_same {
   static constexpr bool value = false;
-- 
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