Version: 2023.2+
This example demonstrates how to create custom controls and use the Vector API to draw visual content onto a visual elementA node of a visual tree that instantiates or derives from the C# VisualElement
class. You can style the look, define the behaviour, and display it on screen as part of the UI. More info
See in Glossary.
This example creates a custom control that displays progress, as an alternative to a loading bar. The progress indicator displays a progress value in a partially filled ring around a label that displays the percentage. It supports a value between 0 and 100, which determines how much of the ring is filled.
You can find the completed files that this example creates in this GitHub repository.
This guide is for developers familiar with the Unity Editor, UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
See in Glossary Toolkit, and C# scripting. Before you start, get familiar with the following:
Create a C# script to define a RadialProgress
visual element and a C# script to define the custom meshThe main graphics primitive of Unity. Meshes make up a large part of your 3D worlds. Unity supports triangulated or Quadrangulated polygon meshes. Nurbs, Nurms, Subdiv surfaces must be converted to polygons. More info
See in Glossary. Style the visual element with a USS file.
radial-progress
to store your files.radial-progress
folder, create a C# script named RadialProgress.cs
with the following content:using Unity.Collections; using UnityEngine; using UnityEngine.UIElements; namespace MyGameUILibrary { // An element that displays progress inside a partially filled circle [UxmlElement] public partial class RadialProgress : VisualElement { // These are USS class names for the control overall and the label. public static readonly string ussClassName = "radial-progress"; public static readonly string ussLabelClassName = "radial-progress__label"; // These objects allow C# code to access custom USS properties. static CustomStyleProperty<Color> s_TrackColor = new CustomStyleProperty<Color>("--track-color"); static CustomStyleProperty<Color> s_ProgressColor = new CustomStyleProperty<Color>("--progress-color"); Color m_TrackColor = Color.gray; Color m_ProgressColor = Color.red; // This is the label that displays the percentage. Label m_Label; // This is the number that the Label displays as a percentage. float m_Progress; // A value between 0 and 100 [UxmlAttribute] public float progress { // The progress property is exposed in C#. get => m_Progress; set { // Whenever the progress property changes, MarkDirtyRepaint() is named. This causes a call to the // generateVisualContents callback. m_Progress = value; m_Label.text = Mathf.Clamp(Mathf.Round(value), 0, 100) + "%"; MarkDirtyRepaint(); } } // This default constructor is RadialProgress's only constructor. public RadialProgress() { // Create a Label, add a USS class name, and add it to this visual tree. m_Label = new Label(); m_Label.AddToClassList(ussLabelClassName); Add(m_Label); // Add the USS class name for the overall control. AddToClassList(ussClassName); // Register a callback after custom style resolution. RegisterCallback<CustomStyleResolvedEvent>(evt => CustomStylesResolved(evt)); // Register a callback to generate the visual content of the control. generateVisualContent += GenerateVisualContent; progress = 0.0f; } static void CustomStylesResolved(CustomStyleResolvedEvent evt) { RadialProgress element = (RadialProgress)evt.currentTarget; element.UpdateCustomStyles(); } // After the custom colors are resolved, this method uses them to color the meshes and (if necessary) repaint // the control. void UpdateCustomStyles() { bool repaint = false; if (customStyle.TryGetValue(s_ProgressColor, out m_ProgressColor)) repaint = true; if (customStyle.TryGetValue(s_TrackColor, out m_TrackColor)) repaint = true; if (repaint) MarkDirtyRepaint(); } void GenerateVisualContent(MeshGenerationContext context) { float width = contentRect.width; float height = contentRect.height; var painter = context.painter2D; painter.lineWidth = 10.0f; painter.lineCap = LineCap.Butt; // Draw the track painter.strokeColor = m_TrackColor; painter.BeginPath(); painter.Arc(new Vector2(width * 0.5f, height * 0.5f), width * 0.5f, 0.0f, 360.0f); painter.Stroke(); // Draw the progress painter.strokeColor = m_ProgressColor; painter.BeginPath(); painter.Arc(new Vector2(width * 0.5f, height * 0.5f), width * 0.5f, -90.0f, 360.0f * (progress / 100.0f) - 90.0f); painter.Stroke(); } } }
Create a USS file named RadialProgress.uss
with the following content:
.radial-progress { min-width: 26px; min-height: 20px; --track-color: rgb(130, 130, 130); --progress-color: rgb(46, 132, 24); --percentage-color: white; margin-left: 5px; margin-right: 5px; margin-top: 5px; margin-bottom: 5px; flex-direction: row; justify-content: center; width: 100px; height: 100px; } .radial-progress__label { -unity-text-align: middle-left; color: var(--percentage-color); }
Use UI Builder to add the control and apply the USS stylesheet. Test the control with different Progress
values.
RadialProgressExample.uxml
.RadialProgressExample.uxml
to open it in the UI Builder.RadialProgress.uss
as the existing USS.radial-progress
in the Name box.Create a C# MonoBehaviour script to update the Progress
property of the control with dynamic values for demo purposes. In the radial-progress
folder, create a C# MonoBehaviour named RadialProgressComponent.cs
with the following content:
using MyUILibrary; using UnityEngine; using UnityEngine.UIElements; [RequireComponent(typeof(UIDocument))] public class RadialProgressComponent : MonoBehaviour { RadialProgress m_RadialProgress; void Start() { var root = GetComponent<UIDocument>().rootVisualElement; m_RadialProgress = new RadialProgress() { style = { position = Position.Absolute, left = 20, top = 20, width = 200, height = 200 } }; root.Add(m_RadialProgress); } void Update() { m_RadialProgress.progress = ((Mathf.Sin(Time.time) + 1.0f) / 2.0f) * 60.0f + 10.0f; } }
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