add coloring per text section in gizmos by nuts-rice · Pull Request #23120 · bevyengine/bevy

nuts-rice · 2026-02-23T17:59:09Z

Objective

Resolves bevy_gizmos: Multicolored text support. #23002

Solution

Add StrokeTextLayout::render_with_color_fn() to return polyline and color pairing
Add text_sections() to build concat string consisting of sections of character-coloring pair
Associated helper fn for yielding tuple of (char, Color)
replace text field in StrokeTextLayout with sections that is an iterable &'a [(&'a str, Color)]

Testing

Ran cargo test for gizmos
Prolly could use an example

Showcase

Example Usage:

gizmos.text_sections(iso, [
      ("Hello ", Color::WHITE),
      ("World!", Color::srgb(1., 0., 0.)),
  ], 25., Vec2::ZERO);

github-actions · 2026-02-23T17:59:34Z

Welcome, new contributor!

Please make sure you've read our contributing guide and we look forward to reviewing your pull request shortly ✨

ickshonpe

Yeah this is pretty good, the only problem is the extra allocations, which should be avoidable if StrokeTextLayout's text: &str field is replaced with a slice or iterator. Then make a function, something like:

fn colored_chars(s: &[(&str, Color)]) -> impl Iterator<Item = (char, Color)> {
    s.into_iter()
        .map(|(t, color)| t.chars().map(|c| (c, *color)))
        .flatten()
}

that maps the sections to an iterator that yields the individual chars and their colors for rendering.

ickshonpe · 2026-02-23T22:10:51Z

crates/bevy_gizmos/src/stroke_text.rs

+
+/// Builds a parallel per-character color array.
+fn build_sections<S: AsRef<str>, C: Into<Color>>(
+    sections: impl IntoIterator<Item = (S, C)>,
+) -> (String, Vec<Color>) {
+    let mut full_text = String::new();
+    let mut char_colors: Vec<Color> = Vec::new();
+    for (text, color) in sections {
+        let text = text.as_ref();
+        let color: Color = color.into();
+        full_text.push_str(text);
+        for _ in text.chars() {
+            char_colors.push(color);
+        }
+    }
+    (full_text, char_colors)
+}


Everything else is fine, but we don't want the extra allocations from this function. Instead of this, you could just replace the Chars iterator that is created at the start of the render function with an iterator that yields (char, Color) tuples.

ickshonpe · 2026-02-23T22:31:32Z

crates/bevy_gizmos/src/stroke_text.rs

+    where
+        F: Fn(usize) -> Color + 'a,
+    {
        let mut chars = self.text.chars();


Instead of StrokeTextLayout's text field being an &str, it could be a Clone + IntoIterator<Item = (&'a str, Color)> or just an (&'str, Color) slice. Then it just needs another function that takes an (&'a str, Color) iterator and yields a sequence of (char, Color)s. So this line would become something like:

Suggested change

let mut chars = self.text.chars();

let mut colored_chars = self.colored_chars();

ickshonpe · 2026-02-23T22:33:34Z

crates/bevy_gizmos/src/stroke_text.rs

            let c = chars.next()?;
+            let char_color = color_fn(char_idx);


Then here, the iterator yields the char and color together:

Suggested change

let c = chars.next()?;

let char_color = color_fn(char_idx);

let (c, char_color) = colored_chars.next()?;

and everything else should work?

ickshonpe · 2026-02-24T09:33:11Z

Sorry was really tired last night and my review comments were kind of rambling, hopefully you get the idea though.

nuts-rice · 2026-02-24T14:43:18Z

you're alright, gonna resolve them soon

github-actions · 2026-02-24T23:03:24Z

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.

ickshonpe

Looks good now, everything seems to work:

Just needs the text_gizmos.md release note to be updated to include these changes, and I think the uncolored render function should be removed as not useful.

ickshonpe · 2026-02-24T23:08:59Z

crates/bevy_gizmos/src/stroke_text.rs

+
+    /// Returns an iterator over the font strokes for this text layout, grouped into polylines
+    /// of `Vec2` points, each paired with its color from the text sections.
+    pub fn render_colored(


Suggested change

pub fn render_colored(

pub fn render(

ickshonpe · 2026-02-24T23:10:51Z

crates/bevy_gizmos/src/stroke_text.rs

    /// Returns an iterator over the font strokes for this text layout,
    /// grouped into polylines of `Vec2` points.
    pub fn render(&'a self) -> impl Iterator<Item = impl Iterator<Item = Vec2>> + 'a {
-        let mut chars = self.text.chars();
-        let mut x = 0.0;
+        self.render_colored().map(|(_, stroke)| stroke)
+    }


Doesn't seem like this function is useful anymore, should just delete it and rename the other one back to render I think.

ickshonpe · 2026-02-24T23:40:25Z

release-content/release-notes/text_gizmos.md

@@ -4,11 +4,12 @@ authors: ["@ickshonpe"]
 pull_requests: [22732]


Suggested change

pull_requests: [22732]

pull_requests: [22732, 23120]

ickshonpe · 2026-02-24T23:43:03Z

release-content/release-notes/text_gizmos.md

Got to add yourself 😄

feat: add coloring per text section

c148a06

alice-i-cecile requested a review from ickshonpe February 23, 2026 19:11

alice-i-cecile added C-Feature A new feature, making something new possible A-Gizmos Visual editor and debug gizmos A-Text Rendering and layout for characters S-Needs-Review Needs reviewer attention (from anyone!) to move forward labels Feb 23, 2026

alice-i-cecile added this to the 0.19 milestone Feb 23, 2026

ickshonpe suggested changes Feb 23, 2026

View reviewed changes

fix(gizmos): add sections field + colored_chars fn

75fdaa2

ickshonpe added the M-Release-Note Work that should be called out in the blog due to impact label Feb 24, 2026

ickshonpe suggested changes Feb 24, 2026

View reviewed changes

ickshonpe approved these changes Feb 24, 2026

View reviewed changes

nuts-rice force-pushed the main branch 2 times, most recently from ccf1541 to ed05f64 Compare February 24, 2026 23:47

docs: text release note for per-section color

4fe9741

nuts-rice force-pushed the main branch from ed05f64 to 4fe9741 Compare February 24, 2026 23:52

chore: fmt

55fe2e6

	let mut chars = self.text.chars();
	let mut colored_chars = self.colored_chars();

	let c = chars.next()?;
	let char_color = color_fn(char_idx);
	let (c, char_color) = colored_chars.next()?;

		@@ -4,11 +4,12 @@ authors: ["@ickshonpe"]
		pull_requests: [22732]

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Testing

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