upstream: jackdaw transform gizmo by jbuehler23 · Pull Request #23435 · bevyengine/bevy

jbuehler23 · 2026-03-20T12:08:10Z

Objective

Upstream jackdaw's TransformGizmo!

Solution

Add TransformGizmoPlugin to bevy_gizmos as an optional plugin that draws on a focused entity and lets the user click/drag to manipulate its transform. Rotate, Translate, and Scale are all individual gizmos - perfect opportunity for someone to extend and create a combined gizmo in a follow-up :)

Testing

Manually tested with cargo run --example transform_gizmo --features free_camera:
- All three modes (translate, rotate, scale) work
- Focus switch between objects, and gizmo moves across
- World/local space toggle and editing
Tested on Linux (X11)

Showcase

Mark any entity with TransformGizmoFocus to get interactive handles:

app.add_plugins(TransformGizmoPlugin);

commands.spawn((
    Mesh3d(mesh),
    MeshMaterial3d(material),
    TransformGizmoFocus,
));
 

// Switch modes via resource
mode.set(TransformGizmoMode::Rotate);

The transform_gizmo example shows input cycling and keyboard mode switching (1/2/3 for translate/rotate/scale, X to toggle world/local space)

Video

Jackdaw

gizmo_demo.mp4

Transform Example

bevy_transform_gizmo.mp4

crates/bevy_gizmos/src/transform_gizmo.rs

PatrickChodowski

I hope you don't mind review from common user :) I tried out this transform gizmo in my own project and I really like the design. I think separating the translation, rotation and scale is a very good idea.

I added some comments that I believe is useful feedback ( the Single camera especially surprised me in the beginning because in the project I have a general main camera but also another camera to get a depth texture)

Thank you for your work

github-actions · 2026-03-22T19:05:33Z

It looks like your PR has been selected for a highlight in the next release blog post, but you didn't provide a release note.

Please review the instructions for writing release notes, then expand or revise the content in the release notes directory to showcase your changes.

alice-i-cecile · 2026-03-22T19:05:45Z

I hope you don't mind review from common user

Bevy explicitly encourages this! Thanks; this is really helpful feedback.

jbuehler23 · 2026-03-23T19:36:26Z

I hope you don't mind review from common user :) I tried out this transform gizmo in my own project and I really like the design. I think separating the translation, rotation and scale is a very good idea.

I added some comments that I believe is useful feedback ( the Single camera especially surprised me in the beginning because in the project I have a general main camera but also another camera to get a depth texture)

Thank you for your work

Much appreciated for the review, I'll go through these and address them

jbuehler23 · 2026-03-24T06:45:11Z

@PatrickChodowski I'm pretty sure I've addressed all your feedback, and all very valid! I've pushed the latest changes here if you want to take another look

PatrickChodowski

Thank you for the changes! It looks good to me. I have been using this gizmo last couple of days in my project and It feels good

jbuehler23 · 2026-03-24T10:32:18Z

I've added the release note as well, once CI is passing ready for a final review @alice-i-cecile :)

alice-i-cecile · 2026-03-24T20:30:18Z

crates/bevy_gizmos/src/transform_gizmo.rs

+        drag_state.axis = None;
+        drag_state.entity = None;
+        if config.confine_cursor {
+            cursor_opts.grab_mode = CursorGrabMode::None;


This isn't quite right: we need to be resetting the cursor grab mode to the previous state, not None. Caching this in a Local is probably the way.

alice-i-cecile · 2026-03-24T20:32:37Z

crates/bevy_gizmos/src/transform_gizmo.rs

+    }
+
+    // End drag
+    if drag_state.active && mouse.just_released(MouseButton::Left) {


This is not robust enough: just_released events can be missed if focus is lost.

We need to be careful that the drag state doesn't persist indefinitely.

I can actually reproduce this bug by starting to drag, then Alt-Tabbing away.

alice-i-cecile · 2026-03-24T20:37:22Z

crates/bevy_gizmos/src/transform_gizmo.rs

+//! # use bevy_app::App;
+//! # use bevy_gizmos::transform_gizmo::{TransformGizmoPlugin, TransformGizmoFocus};
+//! // 1. Add the plugin
+//! // app.add_plugins(TransformGizmoPlugin);


I don't like this style where we comment out lines and no_run the doc test.

IMO simply using words is going to be clearer.

alice-i-cecile · 2026-03-24T20:39:49Z

crates/bevy_gizmos/src/transform_gizmo.rs

+
+/// Marker component for the camera the transform gizmo should use.
+///
+/// If no camera has this component, the gizmo systems will silently do nothing.


This behavior kind of sucks. We should fallback more gracefully, using the only camera that exists, and then warning loudly if more than one are present and we need to choose.

alice-i-cecile · 2026-03-24T20:40:30Z

crates/bevy_gizmos/src/transform_gizmo.rs

+    Scale,
+}
+
+/// Whether the gizmo operates in world or local space.


Suggested change

/// Whether the gizmo operates in world or local space.

/// Whether the gizmo transforms the object using world or local space axes.

alice-i-cecile · 2026-03-24T20:43:01Z

crates/bevy_gizmos/src/transform_gizmo.rs

+/// Which manipulation mode the gizmo is in.
+#[derive(Resource, Default, PartialEq, Eq, Clone, Copy, Debug, Reflect)]
+#[reflect(Resource, Default)]
+pub enum TransformGizmoMode {


There are a lot of resources here, which will almost always be accessed together. Could we cut this down to 2: TransformGizmoState and TransformGizmoSettings?

alice-i-cecile · 2026-03-24T20:46:45Z

crates/bevy_gizmos/src/transform_gizmo.rs

+
+                let raw_delta = axis_dir * projected * scale;
+                let snapped_delta = match config.snap_translate {
+                    Some(inc) => snap_vec3(raw_delta, inc),


We should only be snapping the axis that is being modified.

alice-i-cecile · 2026-03-24T20:49:12Z

examples/gizmos/transform_gizmo.rs

+        ))
+        .observe(on_click_select);
+
+    // Sphere


There are a number of subtle interactions in this code WRT local vs global behavior and parenting.

I would prefer to swap the sphere and cylinder out for a compound object of some form.

alice-i-cecile · 2026-03-24T20:50:22Z

crates/bevy_gizmos/src/transform_gizmo.rs

+                let scale = cam_dist * config.translate_sensitivity;
+
+                let raw_delta = axis_dir * projected * scale;
+                let snapped_delta = match config.snap_translate {


Is this correct? Shouldn't we be snapping the final coordinates, not the delta?

alice-i-cecile · 2026-03-24T20:51:03Z

examples/gizmos/transform_gizmo.rs

+    ));
+}
+
+fn on_click_select(


This should have a quick filter for PointButton::Primary just to teach good practices.

alice-i-cecile · 2026-03-24T20:53:07Z

crates/bevy_gizmos/src/transform_gizmo.rs

+    normal: Vec3,
+    radius: f32,
+) -> f32 {
+    const RING_SAMPLES: usize = 16;


Suggested change

const RING_SAMPLES: usize = 16;

const RING_SAMPLES: usize = 64;

We don't need to cheap out here.

alice-i-cecile · 2026-03-24T20:54:07Z

examples/gizmos/transform_gizmo.rs

+    // Instructions
+    commands.spawn((
+        Text::new(
+            "Click an object to select it\n1: Translate | 2: Rotate | 3: Scale | X: Toggle space",


We should just use the standard Blender hotkey shortcuts for these modes.

i believe in blender it's 'S' to scale, but that conflicts with the free camera WASD movement right?

alice-i-cecile · 2026-03-24T20:55:01Z

examples/gizmos/transform_gizmo.rs

+    commands.spawn((
+        Text::new(
+            "Click an object to select it\n1: Translate | 2: Rotate | 3: Scale | X: Toggle space",
+        ),


"Toggle space" is unclear. "World/Local space" or something would be better.

aevyrie · 2026-03-24T21:11:50Z

The transform math doesn't seem to actually be projecting the user's drag distance, making the gizmo feel laggy and unresponsive - it doesn't "stick" to the user's pointer.
There looks to be some frame lag, the gizmo and object update at different frames.
Are you accounting for different camera projections?

This is all handled in bevy_transform_gizmo fwiw.

227469248-726b21c8-5308-49f0-9b04-e567833774e1.mp4

Not saying we should upstream that instead, it is horribly out of date, but the math has already been written, we should do it correctly.

jbuehler23 · 2026-03-24T21:29:02Z

The transform math doesn't seem to actually be projecting the user's drag distance, making the gizmo feel laggy and unresponsive - it doesn't "stick" to the user's pointer.

There looks to be some frame lag, the gizmo and object update at different frames.

Are you accounting for different camera projections?

This is all handled in bevy_transform_gizmo fwiw.

227469248-726b21c8-5308-49f0-9b04-e567833774e1.mp4
Not saying we should upstream that instead, it is horribly out of date, but the math has already been written, we should do it correctly.

oh sick, thank you i'll have a look at the math here

chompaa · 2026-03-24T23:39:09Z

Adding to Aevyrie's comments about prior art - I mentioned this on Discord as well but also mentioning on here for visibility. I think it's also worth checking out transform-gizmo. Its bevy integration is only slightly out of date (0.17). It is agnostic w.r.t. rendering and transforms, and the UX feels great (I think it's just like Blender's?) Being transform agnostic is pretty important for a gizmo like this IMO.

8th-Boundary · 2026-03-25T23:53:38Z

https://github.com/8th-Boundary/bevy_transform_tools
Can take a look here as well for another reference.

jbuehler23 added A-Gizmos Visual editor and debug gizmos C-Feature A new feature, making something new possible labels Mar 20, 2026

upstream: jackdaw transform gizmo

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jbuehler23 force-pushed the transform-gizmo branch from c12d861 to cba6a4c Compare March 20, 2026 12:34

Merge branch 'main' into transform-gizmo

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PatrickChodowski reviewed Mar 22, 2026

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PatrickChodowski reviewed Mar 22, 2026

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alice-i-cecile added A-Editor Graphical tools to make Bevy games S-Needs-Review Needs reviewer attention (from anyone!) to move forward labels Mar 22, 2026

alice-i-cecile requested review from Atlas16A and kfc35 March 22, 2026 19:05

alice-i-cecile added the M-Release-Note Work that should be called out in the blog due to impact label Mar 22, 2026

alice-i-cecile added S-Waiting-on-Author The author needs to make changes or address concerns before this can be merged and removed S-Needs-Review Needs reviewer attention (from anyone!) to move forward labels Mar 22, 2026

Address PR review: SparseSet storage, camera marker, and SystemSet

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jbuehler23 force-pushed the transform-gizmo branch from 8c1ae4f to 5a2cbb6 Compare March 24, 2026 06:52

PatrickChodowski approved these changes Mar 24, 2026

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Add release note for transform gizmo

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jbuehler23 and others added 2 commits March 24, 2026 10:32

Merge branch 'main' into transform-gizmo

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Move release note to correct folder

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alice-i-cecile reviewed Mar 24, 2026

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Copyediting for module docs

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alice-i-cecile mentioned this pull request Mar 24, 2026

Add "align view to axes" shortcuts #23499

Open

alice-i-cecile added the X-Contentious There are nontrivial implications that should be thought through label Mar 25, 2026

jbuehler23 added 2 commits March 26, 2026 06:36

Address feedback

4ca23ff

Mesh-based gizmo rendering with overlay camera

9356d59

	/// Whether the gizmo operates in world or local space.
	/// Whether the gizmo transforms the object using world or local space axes.

	const RING_SAMPLES: usize = 16;
	const RING_SAMPLES: usize = 64;

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jbuehler23 commented Mar 20, 2026

Objective

Solution

Testing

Showcase

Video

Jackdaw

Transform Example

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aevyrie commented Mar 24, 2026

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jbuehler23 commented Mar 24, 2026

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chompaa commented Mar 24, 2026

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8th-Boundary commented Mar 25, 2026

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