Fix possible corrupt font atlas

2 files changed, 29 insertions, 10 deletions

diff --git a/include/mgl/graphics/font.h b/include/mgl/graphics/font.h
index 6b10feb..55d364f 100644
--- a/include/mgl/graphics/font.h
+++ b/include/mgl/graphics/font.h
@@ -22,6 +22,8 @@ typedef struct {
     int prev_height;
     mgl_vec2i pointer_position;
     mgl_font_atlas_render_section render_section;
+    int initial_section_height;
+    int right_section_height;
 } mgl_font_atlas;
 
 struct mgl_font {
@@ -30,6 +32,7 @@ struct mgl_font {
     mgl_font_atlas font_atlas;
     unsigned int character_size;
     mgl_font_char_map char_map;
+    int current_line_max_height;
     void *font_info;
 };
 
diff --git a/src/graphics/font.c b/src/graphics/font.c
index fd1439d..82a8029 100644
--- a/src/graphics/font.c
+++ b/src/graphics/font.c
@@ -16,6 +16,10 @@ static int round_float(float value) {
     return value + 0.5f;
 }
 
+static int max_int(int a, int b) {
+    return a >= b ? a : b;
+}
+
 int mgl_font_load_from_file(mgl_font *self, const mgl_memory_mapped_file *mapped_file, unsigned int character_size) {
     self->texture.id = 0;
 
@@ -25,9 +29,12 @@ int mgl_font_load_from_file(mgl_font *self, const mgl_memory_mapped_file *mapped
     self->font_atlas.prev_height = 0;
     self->font_atlas.pointer_position = (mgl_vec2i){ GLYPH_PADDING, GLYPH_PADDING };
     self->font_atlas.render_section = MGL_ATLAS_SECTION_INITIAL;
+    self->font_atlas.initial_section_height = 0;
+    self->font_atlas.right_section_height = 0;
 
     self->character_size = character_size;
     mgl_font_char_map_init(&self->char_map);
+    self->current_line_max_height = 0;
     self->font_info = NULL;
 
     self->font_info = malloc(sizeof(stbtt_fontinfo));
@@ -51,6 +58,7 @@ void mgl_font_unload(mgl_font *self) {
     mgl_texture_unload(&self->texture);
 
     mgl_font_char_map_deinit(&self->char_map);
+    self->current_line_max_height = 0;
 
     free(self->font_info);
     self->font_info = NULL;
@@ -64,9 +72,9 @@ static int align_up_to_next_value_of(int value, int alignment) {
         return value + (alignment - offset_to_next_alignment);
 }
 
-static void mgl_font_handle_new_render_position(mgl_font *self, int glyph_width, int glyph_height) {
+static void mgl_font_handle_new_render_position(mgl_font *self, int glyph_width) {
     if(self->font_atlas.pointer_position.x + glyph_width + GLYPH_PADDING >= self->font_atlas.width) {
-        if(self->font_atlas.pointer_position.y + glyph_height + GLYPH_PADDING >= self->font_atlas.height && self->font_atlas.render_section != MGL_ATLAS_SECTION_RIGHT) {
+        if(self->font_atlas.pointer_position.y + self->current_line_max_height + (int)self->character_size + GLYPH_PADDING >= self->font_atlas.height && self->font_atlas.render_section != MGL_ATLAS_SECTION_RIGHT) {
             /*
                 Texture atlas looks like this with glyphs filling the texture:
                 |----|
@@ -91,11 +99,14 @@ static void mgl_font_handle_new_render_position(mgl_font *self, int glyph_width,
 
             /* Texture overflow, enlargen the font atlas! */
             /* TODO: Create a new texture and copy the texture content instead of rendering all glyphs again */
-            if(mgl_texture_resize(&self->texture, self->font_atlas.width * 2, self->font_atlas.height * 2, NULL) == 0) {
+            const int new_width = align_up_to_next_value_of(self->font_atlas.width * 2, self->character_size + GLYPH_PADDING);
+            const int new_height = align_up_to_next_value_of(self->font_atlas.height * 2, self->character_size + GLYPH_PADDING);
+            if(mgl_texture_resize(&self->texture, new_width, new_height, NULL) == 0) {
+                self->font_atlas.initial_section_height = self->font_atlas.pointer_position.y + self->current_line_max_height;
                 self->font_atlas.prev_width = self->font_atlas.width;
                 self->font_atlas.prev_height = self->font_atlas.height;
-                self->font_atlas.width = align_up_to_next_value_of(self->font_atlas.width * 2, self->character_size);
-                self->font_atlas.height = align_up_to_next_value_of(self->font_atlas.height * 2, self->character_size);
+                self->font_atlas.width = new_width;
+                self->font_atlas.height = new_height;
 
                 self->font_atlas.render_section = MGL_ATLAS_SECTION_RIGHT;
                 self->font_atlas.pointer_position.x = self->font_atlas.prev_width;
@@ -113,18 +124,20 @@ static void mgl_font_handle_new_render_position(mgl_font *self, int glyph_width,
             } else {
                 fprintf(stderr, "Error: failed to resize font atlas\n");
             }
-        } else if(self->font_atlas.render_section == MGL_ATLAS_SECTION_RIGHT && self->font_atlas.pointer_position.y + glyph_height + GLYPH_PADDING >= self->font_atlas.prev_height) {
+        } else if(self->font_atlas.render_section == MGL_ATLAS_SECTION_RIGHT && self->font_atlas.pointer_position.y + self->current_line_max_height + (int)self->character_size + GLYPH_PADDING >= self->font_atlas.prev_height) {
+            self->font_atlas.right_section_height = self->font_atlas.pointer_position.y + self->current_line_max_height;
             self->font_atlas.render_section = MGL_ATLAS_SECTION_BOTTOM;
             self->font_atlas.pointer_position.x = GLYPH_PADDING;
-            self->font_atlas.pointer_position.y += self->character_size + GLYPH_PADDING;
+            self->font_atlas.pointer_position.y = max_int(self->font_atlas.initial_section_height, self->font_atlas.right_section_height) + GLYPH_PADDING;
         } else {
             if(self->font_atlas.render_section != MGL_ATLAS_SECTION_RIGHT) {
                 self->font_atlas.pointer_position.x = GLYPH_PADDING;
             } else {
                 self->font_atlas.pointer_position.x = self->font_atlas.prev_width;
             }
-            self->font_atlas.pointer_position.y += self->character_size + GLYPH_PADDING;
+            self->font_atlas.pointer_position.y += self->current_line_max_height + GLYPH_PADDING;
         }
+        self->current_line_max_height = 0;
     }
 }
 
@@ -136,7 +149,7 @@ int mgl_font_get_glyph(mgl_font *self, uint32_t codepoint, mgl_font_glyph *glyph
         if(self->texture.id == 0 && mgl_texture_init(&self->texture) != 0)
             return -1;
 
-        const int initial_atlas_size = align_up_to_next_value_of(128, self->character_size);
+        const int initial_atlas_size = align_up_to_next_value_of(128, self->character_size + GLYPH_PADDING);
         /* TODO: Scale by character size */
         mgl_texture_load_options load_options = {
             .compressed = false,
@@ -198,7 +211,7 @@ int mgl_font_get_glyph(mgl_font *self, uint32_t codepoint, mgl_font_glyph *glyph
     if(existing_char_entry) {
         render_offset = existing_char_entry->render_offset;
     } else {
-        mgl_font_handle_new_render_position(self, width, height);
+        mgl_font_handle_new_render_position(self, width);
         render_offset.x = self->font_atlas.pointer_position.x;
         render_offset.y = self->font_atlas.pointer_position.y;
 
@@ -217,6 +230,9 @@ int mgl_font_get_glyph(mgl_font *self, uint32_t codepoint, mgl_font_glyph *glyph
         }
         existing_char_entry->render_offset = render_offset;
 
+        if(height > self->current_line_max_height)
+            self->current_line_max_height = height;
+
         self->font_atlas.pointer_position.x += width + GLYPH_PADDING;
     }