Ported Imgui-knobs

[Logickin-Lambda]

Thanks for waiting the setup of my new laptop before going back on working my proposal of porting the knob library.

As proposed in the issues, the library can be conditionally compiled by stating .with_knobs with true:

// zgui
const zgui = b.dependency("zgui", .{
    .shared = false,
    .with_knobs = true,
    .backend = .glfw_wgpu,
   });
exe.root_module.addImport("zgui", zgui.module("root"));
exe.linkLibrary(zgui.artifact("imgui"));

Once the knob part is included, simply call zgui.knobs.knob to create a knob:

// Minimal knob function call
_ = zgui.knobs.knob("Minimal", .{
    .v = &v_knob,
    .v_min = 0,
    .v_max = 1.0,
});

For different knob style, resolution per step, arc shape, and color, we can apply with the additional parameter like shown:

// Styled f32 knob
_ = zgui.knobs.knob("f32 Knob", .{
    .v = &v_knob,
    .v_min = 0,
    .v_max = 1.0,
    .size = 200,
    .speed = 0.0005,
    .angle_min = std.math.pi,
    .angle_max = 2 * std.math.pi,
    .variant = .{ .stepped = true },
    .steps = 5,
});

// Styled i32 knob (applied color)
zgui.pushStyleColor4f(.{ .idx = zgui.StyleCol.button_active, .c = .{ 0.6, 0.2, 0.2, 1 } });
zgui.pushStyleColor4f(.{ .idx = zgui.StyleCol.button_hovered, .c = .{ 0.6, 0.4, 0.4, 1 } });
zgui.pushStyleColor4f(.{ .idx = zgui.StyleCol.button, .c = .{ 0.4, 0, 0, 1 } });
_ = zgui.knobs.knobInt("i32 Knob", .{
    .v = &v_knob_int,
    .v_min = -10,
    .v_max = 10,
    .size = 250,
    .variant = zgui.knobs.KnobVariant{ .wiper_dot = true },
    .flags = zgui.knobs.KnobFlags{
        .drag_horizontal = true,
        .no_input = true,
    },
});
zgui.popStyleColor(.{ .count = 3 });

The result based on the function call above (applied with zgui,sameLine() for the alignments):

Knobs.in.demo.mp4

Time for some code review, and let see if there are further requests to follow.

[Copilot]

Pull Request Overview

This PR ports the imgui-knobs library to zgui, enabling the creation of knob UI controls. The integration is optional and can be enabled with the with_knobs build flag.

• Adds a Zig wrapper for the imgui-knobs C++ library with type-safe API
• Integrates the imgui-knobs source code and provides conditional compilation
• Provides both float and integer knob variants with extensive customization options

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/zknobs.cpp	C++ wrapper functions to bridge imgui-knobs with Zig
src/knobs.zig	Zig API providing type-safe knob functions and configuration structs
src/gui.zig	Exports the knobs module when available
libs/imgui_knobs/imgui-knobs.h	Header file for the imgui-knobs library
libs/imgui_knobs/imgui-knobs.cpp	Implementation of the imgui-knobs library
libs/imgui_knobs/LICENSE	MIT license for the imgui-knobs library
build.zig	Build configuration to conditionally include knobs support
README.md	Documentation and usage examples for the knobs API

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[hazeycode]

Please list the knobs lib version under the Versons section in the README.

[Logickin-Lambda]

After I have taken a look into the library, I just found it doesn't have a specific release version, so I am think of stating the last commit date of the library before I have ported it (which is 23 June 2025) or the commit id (8a43bf7) instead because giving it an arbitrary version will not reflect the actual version of the library and it might cause confusion.

There is a chance that the library is small and the update is infrequent, so they don't really care to put them as a release.

If you have concern about my approach, please let me know such that I will notify the author behind the knob library and hopefully they could do a proper release.

[hazeycode]

The branch name + commit hash is sufficient.

[Logickin-Lambda]

Done! Besides added the version, clicking the link of the version to the knobs will redirect to that particular commit history as well.