texture atlas top & left padding by Wuketuke · Pull Request #23056 · bevyengine/bevy

Wuketuke · 2026-02-19T13:41:11Z

A TextureAtlas can now have padding on the top and left edge.
Since the user probably wants to set this together with the normal padding, i changed the TextureAtlasBuilder::padding function so that both the initial padding and the per-image padding gets set together.
Should the user wish to have a different initial padding value, i added a initial_padding function

Testing

i ran the 2d/texture_atlas.rs example, and saved each image to a file.
i then manually checked if the padding is inserted correctly
for that i slightly modified the example code like this

fn create_texture_atlas( ... ) {
    // ...
    // line 247
    let (texture_atlas_layout, texture_atlas_sources, texture) =
        texture_atlas_builder.build().unwrap();

    let nr = counter();
    println!("SAVING IMAGE");
    texture
        .convert(bevy_render::render_resource::TextureFormat::Rgba8UnormSrgb)
        .unwrap()
        .try_into_dynamic()
        .unwrap()
        .save(format!("TEMP_{nr}.png"))
        .unwrap();

    let texture = textures.add(texture);

    // ...
}

static TEMP: std::sync::OnceLock<std::sync::Mutex<u8>> = std::sync::OnceLock::new();
fn counter() -> u8 {
    let x = TEMP.get_or_init(|| std::sync::Mutex::new(0));
    let mut x = x.lock().unwrap();
    let val = *x;
    *x += 1;
    val
}

kfc35 · 2026-02-20T00:55:25Z

@@ -104,8 +104,20 @@ impl<'a> TextureAtlasBuilder<'a> {
    /// Sets the amount of padding in pixels to add between the textures in the texture atlas.
    ///
    /// The `x` value provide will be added to the right edge, while the `y` value will be added to the bottom edge.
+    ///
+    /// calling this function will also set the initial padding (on the top and left edge).


Suggested change

/// calling this function will also set the initial padding (on the top and left edge).

/// calling this function will also set the initial padding (`x` for the left edge and `y` for the top)

kfc35 · 2026-02-20T00:56:01Z

@@ -104,8 +104,20 @@ impl<'a> TextureAtlasBuilder<'a> {
    /// Sets the amount of padding in pixels to add between the textures in the texture atlas.
    ///
    /// The `x` value provide will be added to the right edge, while the `y` value will be added to the bottom edge.
+    ///
+    /// calling this function will also set the initial padding (on the top and left edge).
+    /// call [`initial_padding`] to set that value only


Suggested change

/// call [`initial_padding`] to set that value only

/// call [`initial_padding`](TextureAtlasBuilder::initial_padding) to set the left and top padding values only

kfc35 · 2026-02-20T00:57:00Z

+        self
+    }
+
+    /// Sets the amount of padding in pixels to add on the top and left edge of the texture atlas.


Suggested change

/// Sets the amount of padding in pixels to add on the top and left edge of the texture atlas.

/// Sets the amount of padding in pixels to add on the left and top edge of the texture atlas.

just to make it consistent that the “first” aka x number is for the left edge

ickshonpe · 2026-02-20T12:35:02Z

Sign in to view

@@ -114,13 +126,14 @@ impl<'a> TextureAtlasBuilder<'a> {
        texture: &Image,
        packed_location: &PackedLocation,
        padding: UVec2,
+        init_padding: UVec2,
    ) -> TextureAtlasBuilderResult<()> {
        let rect_width = (packed_location.width() - padding.x) as usize;


No, it still pack the rects with padding only added on the bottom and right. Rectangle Pack is passed a single TargetBin with its size equal to the atlas target size minus initial_padding. Then the returned packed rects are displaced right and down by intial_padding to leave the top left padded region clear.

ickshonpe

I added an atlas test thing to testbed_2d (#23074) and everything looks good:

The default texture atlas packing behaviour is changed, so we need a migration guide. Just has to explain that padding is now added on the top and left edges, and that users can call initial_padding(UVec2::ZERO) to get the old behaviour.

ickshonpe · 2026-02-20T11:38:29Z

+    /// The padding along the left and top edges of the `TextureAtlas`
+    initial_padding: UVec2,


I don't think there's any reason we would want the top left to have a different padding thickness. It might be clearer to just make this a bool, and reuse the value from the padding field.

…23091) # Objective - #22939 has been introducing diffs in the testbed_ui Text example, but the only thing that was changing was the order that glyphs are allocated to the font atlas. The font atlas **should be** resilient to this and produce no diffs in that case. - Another PR had similar diffs and also seemed to be due to changing the order of glyphs being allocated. ## Solution - Previously `DynamicTextureAtlasBuilder` would allocate glyph size + padding, and then copy the glyph into that rectangle - but this means that copying would start at (0,0) meaning we would "blend" with the top and left edges (which breaks things). - Now we copy to (padding, padding). - Remove (padding, padding) allocate-able space from the bottom and right to ensure we don't accidentally put textures on the right or bottom edges. ## Testing - Added unit tests to ensure that allocation works and that padding works. - The rendering change here is quite interesting! https://pixel-eagle.com/project/B04F67C0-C054-4A6F-92EC-F599FEC2FD1D?filter=PR-23091 Some cases, like the `l` in `black` in the Text screenshot look **substantially** better! Note this is orthogonal to #23056 which is about `TextureAtlasBuilder`, not `DynamicTextureAtlasBuilder`.

ickshonpe · 2026-02-25T10:30:37Z

Added this to the release note included with #23132

…m/Wuketuke/bevy into issue-22776_texture-atlas-padding

github-actions · 2026-03-11T16:56:46Z

Your PR caused a change in the graphical output of an example or rendering test. This might be intentional, but it could also mean that something broke!
You can review it at https://pixel-eagle.com/project/B04F67C0-C054-4A6F-92EC-F599FEC2FD1D?filter=PR-23056

If it's expected, please add the M-Deliberate-Rendering-Change label.

If this change seems unrelated to your PR, you can consider updating your PR to target the latest main branch, either by rebasing or merging main into it.

github-actions · 2026-03-11T16:58:13Z

Your PR caused a change in the graphical output of an example or rendering test. This might be intentional, but it could also mean that something broke!
You can review it at https://pixel-eagle.com/project/B04F67C0-C054-4A6F-92EC-F599FEC2FD1D?filter=PR-23056

If it's expected, please add the M-Deliberate-Rendering-Change label.

If this change seems unrelated to your PR, you can consider updating your PR to target the latest main branch, either by rebasing or merging main into it.

github-actions · 2026-05-05T01:48:14Z

Your PR caused a change in the graphical output of an example or rendering test. This might be intentional, but it could also mean that something broke!
You can review it at https://pixel-eagle.com/project/B04F67C0-C054-4A6F-92EC-F599FEC2FD1D?filter=PR-23056

If it's expected, please add the M-Deliberate-Rendering-Change label.

If this change seems unrelated to your PR, you can consider updating your PR to target the latest main branch, either by rebasing or merging main into it.

# Objective - Migration guide merged in release-content ## Solution - Move it - Add a CI check that will block new merges Opened PRs that sill change that folder: - bevyengine#23467 - bevyengine#23445 - bevyengine#23373 - bevyengine#23137 - bevyengine#23132 - bevyengine#23056 - bevyengine#22917 - bevyengine#22852 - bevyengine#22782 - bevyengine#22670 - bevyengine#22557 - bevyengine#22500 - bevyengine#21929 - bevyengine#21912 - bevyengine#21897 - bevyengine#21893 - bevyengine#21890 - bevyengine#21889 - bevyengine#21839 - bevyengine#21811 - bevyengine#21772 None of them are likely to be merged in the 0.19

ickshonpe · 2026-05-11T13:23:51Z

@Wuketuke do you still want to finish this, or should someone else take it over?

Wuketuke and others added 3 commits February 19, 2026 13:13

added padding to the top and left of a texture atlas

6cd43d5

fixed initial padding not actually working, oops

c34411c

Updated failing ci in Documentation

78fecb6

kfc35 added C-Feature A new feature, making something new possible A-Rendering Drawing game state to the screen D-Straightforward Simple bug fixes and API improvements, docs, test and examples S-Needs-Review Needs reviewer attention (from anyone!) to move forward labels Feb 19, 2026

github-project-automation Bot added this to Rendering Feb 19, 2026

github-project-automation Bot moved this to Needs SME Triage in Rendering Feb 19, 2026

kfc35 reviewed Feb 20, 2026

View reviewed changes

kfc35 requested a review from ickshonpe February 20, 2026 01:02

ickshonpe reviewed Feb 20, 2026

View reviewed changes

ickshonpe added the M-Migration-Guide A breaking change to Bevy's public API that needs to be noted in a migration guide label Feb 20, 2026

andriyDev mentioned this pull request Feb 21, 2026

Fix DynamicTextureAtlasBuilder incorrectly padding added textures. #23091

Merged

alice-i-cecile added S-Waiting-on-Author The author needs to make changes or address concerns before this can be merged X-Uncontroversial This work is generally agreed upon and removed S-Needs-Review Needs reviewer attention (from anyone!) to move forward labels Feb 23, 2026

ickshonpe mentioned this pull request Feb 25, 2026

DynamicTextureAtlasBuilder edge extrusion support #23132

Open

Wuketuke added 3 commits March 11, 2026 17:45

fixed documentation and added migration guide

b360bbc

Merge branch 'issue-22776_texture-atlas-padding' of https://github.co…

cc3b8ca

…m/Wuketuke/bevy into issue-22776_texture-atlas-padding

fixed typo in migration guide

d34087a

mockersf mentioned this pull request Apr 3, 2026

Move release-content content to _release-content #23638

Closed

cart force-pushed the main branch from af894e5 to 017ffc5 Compare May 4, 2026 23:35

Merge branch 'main' into issue-22776_texture-atlas-padding

fb588f2

mockersf mentioned this pull request May 8, 2026

Cleanup release content (one more time) #24198

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texture atlas top & left padding#23056

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	/// calling this function will also set the initial padding (on the top and left edge).
	/// calling this function will also set the initial padding (`x` for the left edge and `y` for the top)

	/// call [`initial_padding`] to set that value only
	/// call [`initial_padding`](TextureAtlasBuilder::initial_padding) to set the left and top padding values only

	/// Sets the amount of padding in pixels to add on the top and left edge of the texture atlas.
	/// Sets the amount of padding in pixels to add on the left and top edge of the texture atlas.

		/// The padding along the left and top edges of the `TextureAtlas`
		initial_padding: UVec2,

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