From d4151e6c76d688d1ead88402f818ff13a65122cd Mon Sep 17 00:00:00 2001
From: griffi-gh <prasol258@gmail.com>
Date: Wed, 6 Mar 2024 21:14:40 +0100
Subject: [PATCH] fix corrupted text bug

---
 hui/src/draw.rs       | 30 ++++++++++++++++++++++++++++++
 hui/src/draw/atlas.rs |  8 ++++++++
 2 files changed, 38 insertions(+)

diff --git a/hui/src/draw.rs b/hui/src/draw.rs
index afc411b..6acd061 100644
--- a/hui/src/draw.rs
+++ b/hui/src/draw.rs
@@ -97,6 +97,32 @@ impl UiDrawCall {
   pub(crate) fn build(draw_commands: &UiDrawCommandList, atlas: &mut TextureAtlasManager, text_renderer: &mut TextRenderer) -> Self {
     let mut trans_stack = Vec::new();
     let mut draw_call = UiDrawCall::default();
+
+    //HACK: atlas may get resized while creating new glyphs,
+    //which invalidates all uvs, causing corrupted-looking texture
+    //so we need to pregenerate font textures before generating any vertices
+    //we are doing *a lot* of double work here, but it's the easiest way to avoid the issue
+    for comamnd in &draw_commands.commands {
+      if let UiDrawCommand::Text { text, font: font_handle, size, .. } = comamnd {
+        let mut layout = Layout::new(CoordinateSystem::PositiveYDown);
+        layout.append(
+          &[text_renderer.internal_font(*font_handle)],
+          &TextStyle::new(text, *size as f32, 0)
+        );
+        let glyphs = layout.glyphs();
+        for layout_glyph in glyphs {
+          if !layout_glyph.char_data.rasterize() { continue }
+          text_renderer.glyph(atlas, *font_handle, layout_glyph.parent, layout_glyph.key.px as u8);
+        }
+      }
+    }
+
+    //note to future self:
+    //RESIZING OR ADDING STUFF TO ATLAS AFTER THIS POINT IS A BIG NO-NO,
+    //DON'T DO IT EVER AGAIN UNLESS YOU WANT TO SPEND HOURS DEBUGGING
+
+    atlas.lock_atlas = true;
+
     for command in &draw_commands.commands {
       match command {
         UiDrawCommand::PushTransform(trans) => {
@@ -328,10 +354,14 @@ impl UiDrawCall {
         }
       }
     }
+
+    atlas.lock_atlas = false;
+
     #[cfg(feature = "pixel_perfect")]
     draw_call.vertices.iter_mut().for_each(|v| {
       v.position = v.position.round()
     });
+
     draw_call
   }
 }
diff --git a/hui/src/draw/atlas.rs b/hui/src/draw/atlas.rs
index 15aa428..812ebe4 100644
--- a/hui/src/draw/atlas.rs
+++ b/hui/src/draw/atlas.rs
@@ -59,6 +59,10 @@ pub(crate) struct TextureAtlasManager {
   /// True if the atlas has been modified in a way which requires a texture reupload
   /// since the beginning of the current frame
   modified: bool,
+
+  /// If true, attempting to modify the atlas in a way which invalidates UVs will cause a panic\
+  /// Used internally to ensure that the UVs do not become invalidated mid-render
+  pub(crate) lock_atlas: bool,
 }
 
 impl TextureAtlasManager {
@@ -73,11 +77,15 @@ impl TextureAtlasManager {
       allocations: HashMap::default(),
       remove_queue: Vec::new(),
       modified: true,
+      lock_atlas: false,
     }
   }
 
   /// Resize the texture atlas to the new size in-place, preserving the existing data
   pub fn resize(&mut self, new_size: UVec2) {
+    if self.lock_atlas {
+      panic!("Attempted to resize the texture atlas while the atlas is locked");
+    }
     log::trace!("resizing texture atlas to {:?}", new_size);
     if self.size == new_size {
       log::warn!("Texture atlas is already the requested size");