bevyengine/bevy Weekly #XX: UI Retained Rendering, Example Migration Wave, and Solari Performance Gains

Period: July 20 – July 26, 2026 · 42 commits in period

This edition highlights the biggest changes from the past week, drawn from 42 commits. If you work with UI, rendering, or bevy_feathers, there's something here for you.

📌 UI & Widgets

UI Render World Data Retention (01107e7)

Patrick Walton landed a foundational patch that stops re-extracting all UI render world data from scratch every frame. Instead, phase items and render-world entities are retained across frames, with ECS change detection driving re-extraction only for changed UI nodes.

• Marked improvement on many_buttons: median frame time went from 48.29 ms → 45.16 ms (1.07× speedup), with much larger gains expected once follow-ups land (retaining SortedRenderPhase items, moving work to extraction phase, GPU preprocessing).
• A side effect: the Changed flag is now set on any visual change, which can trigger unnecessary layout reflows for color-only updates. A follow-up to give layout its own dirty flags is planned.

Scrollbar Autohide & Select Fixes (d30c0cd)

• Scrollbars now autohide by default when content fits the container.
• Re-selecting the currently selected item in a Select widget now closes the popup, thanks to a new ReselectListRow event.
• Added small padding to scrollbar placement inside popups.

AutoFocus Now Distinguishable (6ea281c)

• New FocusCause::Auto variant emitted by AutoFocus, so automatic focus changes no longer masquerade as keyboard/gamepad navigation.

Keyboard Layout Fixes for EditableText (77b17eb)

• Ctrl+A/C/X/V shortcuts now work on non-Latin layouts (Cyrillic, Greek, Hebrew, Arabic, etc.) by falling back to physical key_code when logical_key is not ASCII.

Steam OSK Input (a642af4)

• Editable text inputs now accept produced text from unidentified keys, fixing uppercase and shifted character entry from Steam's on-screen keyboard.

Standalone Build Fix for bevy_ui_widgets (8997cf5)

• Declared the bevy_input_focus/bevy_picking feature dependency so bevy_ui_widgets compiles standalone again.

🎨 Example Migration: Phase 4–6

The ongoing effort to migrate examples from deprecated Button and raw UI logic to bevy_feathers components (FeathersRadio, FeathersNumberInput, FeathersButton, ui_widgets::Button) continues. Kevin Chen led the charge with contributions from Tyler Earls, thomas, and others.

Many of these also convert UI assembly to the bsn! builder macro, reducing boilerplate.

⚡ Rendering & Performance

Solari: Reduced Temporal Shadow Lag (f755ea4)

• Uses the previous frame's TLAS for visibility testing in MIS when merging the temporal reservoir, reducing directional shadow lag. Slight VRAM cost increase.

Solari: Retained Instance Extraction (17ca59b)

• Only extracts changed main-world entities, with dedicated systems for new/deleted entities, transform updates (common case), mesh/material updates (rare), and material set updates. Profiles show significant CPU time reduction in extraction.

Remove Expensive Queue Submit from Sparse Buffer Vec (38d9988)

• Removed a dedicated GPU queue submit that wasn't worth the overhead. The work is now batched into a single compute pass, improving frame times in bevy_city.

dynamic_mip_generation Gains LODs via VisibilityRange (286e81b)

• Most meshes in bevy_city now have LODs, replacing distant meshes with cubes for significant GPU savings. Stats tracking and tweaked defaults included.

Use ECS for Render World Window Data (71372e9)

• Render world window data is now stored as ECS components via SyncToRenderWorld, replacing EntityHashMap lookups. No behavioral changes, but simplifies the codebase.

🛠️ ECS & Platform Improvements

AlignedVec for Safer Shader Buffer Access (bd24f53)

• New AlignedVec type in bevy_platform guarantees runtime-specified alignment, enabling direct bytemuck::cast_slice/cast_slice_mut on shader buffer data without unaligned reads. Used by ShaderBuffer improvements.

ensure! Macro for BevyError (5818e33)

• New ensure! macro that returns a BevyError when a condition is false, mirroring the pattern of bail!.

Split Ordered and Unordered TypeIdMap (09bef1f)

• Restored TypeIdMap as a hash-backed map (average O(1) removal), and added TypeIdIndexMap for the few call sites that need insertion order. Replaced expensive shift_remove calls with remove.

Entity::PLACEHOLDER → Option<Entity> (6b6f6fd)

• Straightforward conversions from Entity::PLACEHOLDER to Option<Entity> in UI code, making null handling more idiomatic.

Default for EntityEquivalentIndexSet (ee1f9f6)

• Removed incorrect Default derive that required a key constraint; added an explicit Default impl that works on any key type.

🔧 Other Fixes & Changes

• Transform Gizmo viewport fix (20166ec): Overlay camera now mirrors the main camera's viewport, fixing gizmo placement on cameras with custom viewports.
• many_text --animate switch (0ecdfaa): Text is now static by default; pass --animate to re-enable the previous behavior.
• compute_mesh type mismatch (e3af87d): Storage buffer type corrected from u32 → f32 to match the shader.
• FromTemplate visibility fix (fdc6cf4): Template struct fields now preserve the visibility of the original type.
• FromTemplate for RenderTarget (daadd06): Manual impl enables RenderTarget use in the bsn! macro.
• ImagePlugin compressed processor extensions (d81f683): New field default_compressed_image_processor_extensions lets users override which file extensions get auto-compressed.
• feathers_gallery uses caption() helper (742979e): Consistent use of the caption shortcut throughout the example.
• fetch_update → try_update (0028119): Fixes deprecation warning on nightly 1.99+.
• Dependency bump (c0404fa): dtolnay/rust-toolchain GitHub Action updated.

Highlights from 42 commits between July 20–26, 2026.