使用 Mesh API 创建径向进度指示器

版本： 2023.2+

此示例演示如何使用网格Unity 的主要图形原语。网格体构成了 3D 世界的很大一部分。Unity 支持三角或四边形多边形网格。Nurbs、Nurms、Subdiv 曲面必须转换为多边形。更多信息
请参阅术语表API 将视觉内容绘制到视觉元素实例化或派生自 C# 的可视化树的节点VisualElement类。您可以设置外观样式、定义行为并将其作为 UI 的一部分显示在屏幕上。更多信息
请参阅术语表.

注意：网格 API 是面向高级用户的工具。在 2022.1 及更高版本中，如果您只想生成简单的几何体，请改用矢量 API。有关详细信息，请参阅使用矢量 API 创建径向进度指示器。

示例概述

此示例创建显示进度的自定义控件，作为加载栏的替代方法。进度指示器在显示百分比的标签周围的部分填充环中显示进度值。它支持一个介于 0 和 100 之间的值，该值决定了填充环的量。

您可以在此 GitHub 存储库中找到此示例创建的已完成文件。

先决条件

本指南适用于熟悉 Unity 编辑器、UI 工具包和 C# 脚本的开发人员。在开始之前，请熟悉以下内容：

创建径向进度指示器及其自定义网格

创建一个 C# 脚本来定义RadialProgress类，并将控件公开给 UXML 和 UI Builder。

使用任何模板创建 Unity 项目。
创建一个名为radial-progress以存储您的文件。
在radial-progress文件夹中，创建一个名为RadialProgress.cs内容如下：

using Unity.Collections;
using UnityEngine;
using UnityEngine.UIElements;

namespace MyUILibrary
{
    /// <summary>
    /// An element that displays progress inside a partially filled circle
    /// </summary>
    [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");

        // These are the meshes this control uses.
        EllipseMesh m_TrackMesh;
        EllipseMesh m_ProgressMesh;

        // This is the label that displays the percentage.
        Label m_Label;

        // This is the number of outer vertices to generate the circle.
        const int k_NumSteps = 200;

        // This is the number that the Label displays as a percentage.
        float m_Progress;

        /// <summary>
        /// A value between 0 and 100
        /// </summary>
        [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);

            // Create meshes for the track and the progress.
            m_ProgressMesh = new EllipseMesh(k_NumSteps);
            m_TrackMesh = new EllipseMesh(k_NumSteps);

            // 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 += context => GenerateVisualContent(context);

            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()
        {
            if (customStyle.TryGetValue(s_ProgressColor, out var progressColor))
            {
                m_ProgressMesh.color = progressColor;
            }

            if (customStyle.TryGetValue(s_TrackColor, out var trackColor))
            {
                m_TrackMesh.color = trackColor;
            }

            if (m_ProgressMesh.isDirty || m_TrackMesh.isDirty)
                MarkDirtyRepaint();
        }

        // The GenerateVisualContent() callback method calls DrawMeshes().
        static void GenerateVisualContent(MeshGenerationContext context)
        {
            RadialProgress element = (RadialProgress)context.visualElement;
            element.DrawMeshes(context);
        }

        // DrawMeshes() uses the EllipseMesh utility class to generate an array of vertices and indices, for both the
        // "track" ring (in grey) and the progress ring (in green). It then passes the geometry to the MeshWriteData
        // object, as returned by the MeshGenerationContext.Allocate() method. For the "progress", only a slice of
        // the index arrays is used to progressively reveal parts of the mesh.
        void DrawMeshes(MeshGenerationContext context)
        {
            float halfWidth = contentRect.width * 0.5f;
            float halfHeight = contentRect.height * 0.5f;

            if (halfWidth < 2.0f || halfHeight < 2.0f)
                return;

            m_ProgressMesh.width = halfWidth;
            m_ProgressMesh.height = halfHeight;
            m_ProgressMesh.borderSize = 10;
            m_ProgressMesh.UpdateMesh();

            m_TrackMesh.width = halfWidth;
            m_TrackMesh.height = halfHeight;
            m_TrackMesh.borderSize = 10;
            m_TrackMesh.UpdateMesh();

            // Draw track mesh first
            var trackMeshWriteData = context.Allocate(m_TrackMesh.vertices.Length, m_TrackMesh.indices.Length);
            trackMeshWriteData.SetAllVertices(m_TrackMesh.vertices);
            trackMeshWriteData.SetAllIndices(m_TrackMesh.indices);

            // Keep progress between 0 and 100
            float clampedProgress = Mathf.Clamp(m_Progress, 0.0f, 100.0f);

            // Determine how many triangle are used to depending on progress, to achieve a partially filled circle
            int sliceSize = Mathf.FloorToInt((k_NumSteps * clampedProgress) / 100.0f);

            if (sliceSize == 0)
                return;

            // Every step is 6 indices in the corresponding array
            sliceSize *= 6;

            var progressMeshWriteData = context.Allocate(m_ProgressMesh.vertices.Length, sliceSize);
            progressMeshWriteData.SetAllVertices(m_ProgressMesh.vertices);

            var tempIndicesArray = new NativeArray<ushort>(m_ProgressMesh.indices, Allocator.Temp);
            progressMeshWriteData.SetAllIndices(tempIndicesArray.Slice(0, sliceSize));
            tempIndicesArray.Dispose();
        }

    }
}

创建自定义网格

创建名为EllipseMesh.cs内容如下：

using UnityEngine;
using UnityEngine.UIElements;

namespace MyUILibrary
{
    public class EllipseMesh
    {
        int m_NumSteps;
        float m_Width;
        float m_Height;
        Color m_Color;
        float m_BorderSize;
        bool m_IsDirty;
        public Vertex[] vertices { get; private set; }
        public ushort[] indices { get; private set; }

        public EllipseMesh(int numSteps)
        {
            m_NumSteps = numSteps;
            m_IsDirty = true;
        }

        public void UpdateMesh()
        {
            if (!m_IsDirty)
                return;

            int numVertices = numSteps * 2;
            int numIndices = numVertices * 6;

            if (vertices == null || vertices.Length != numVertices)
                vertices = new Vertex[numVertices];

            if (indices == null || indices.Length != numIndices)
                indices = new ushort[numIndices];

            float stepSize = 360.0f / (float)numSteps;
            float angle = -180.0f;

            for (int i = 0; i < numSteps; ++i)
            {
                angle -= stepSize;
                float radians = Mathf.Deg2Rad * angle;

                float outerX = Mathf.Sin(radians) * width;
                float outerY = Mathf.Cos(radians) * height;
                Vertex outerVertex = new Vertex();
                outerVertex.position = new Vector3(width + outerX, height + outerY, Vertex.nearZ);
                outerVertex.tint = color;
                vertices[i * 2] = outerVertex;

                float innerX = Mathf.Sin(radians) * (width - borderSize);
                float innerY = Mathf.Cos(radians) * (height - borderSize);
                Vertex innerVertex = new Vertex();
                innerVertex.position = new Vector3(width + innerX, height + innerY, Vertex.nearZ);
                innerVertex.tint = color;
                vertices[i * 2 + 1] = innerVertex;

                indices[i * 6] = (ushort)((i == 0) ? vertices.Length - 2 : (i - 1) * 2); // previous outer vertex
                indices[i * 6 + 1] = (ushort)(i * 2); // current outer vertex
                indices[i * 6 + 2] = (ushort)(i * 2 + 1); // current inner vertex

                indices[i * 6 + 3] = (ushort)((i == 0) ? vertices.Length - 2 : (i - 1) * 2); // previous outer vertex
                indices[i * 6 + 4] = (ushort)(i * 2 + 1); // current inner vertex
                indices[i * 6 + 5] = (ushort)((i == 0) ? vertices.Length - 1 : (i - 1) * 2 + 1); // previous inner vertex
            }

            m_IsDirty = false;
        }

        public bool isDirty => m_IsDirty;

        void CompareAndWrite(ref float field, float newValue)
        {
            if (Mathf.Abs(field - newValue) > float.Epsilon)
            {
                m_IsDirty = true;
                field = newValue;
            }
        }

        public int numSteps
        {
            get => m_NumSteps;
            set
            {
                m_IsDirty = value != m_NumSteps;
                m_NumSteps = value;
            }
        }

        public float width
        {
            get => m_Width;
            set => CompareAndWrite(ref m_Width, value);
        }

        public float height
        {
            get => m_Height;
            set => CompareAndWrite(ref m_Height, value);
        }

        public Color color
        {
            get => m_Color;
            set
            {
                m_IsDirty = value != m_Color;
                m_Color = value;
            }
        }

        public float borderSize
        {
            get => m_BorderSize;
            set => CompareAndWrite(ref m_BorderSize, value);
        }

    }
}

设置自定义控件的样式

创建一个名为 USS 文件RadialProgress.uss内容如下：

.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);
    }

在 UI 文档中使用自定义控件并测试

使用 UI 生成器添加控件并应用 USS 样式表。使用不同的控件测试控件Progress值。

创建名为RadialProgressExample.uxml.
双击RadialProgressExample.uxml在 UI Builder 中打开它。
在“库”窗口中，选择“项目”>“自定义控件”> UxmlSerializedData > MyUILibrary。
将 RadialProgress 拖到“层次结构”窗口。
在 UI Builder 的 StyleSheets 部分中，将RadialProgress.uss作为现有的 USS。
在“层次结构”窗口中，选择“RadialProgress”。
在检查器一个Unity 窗口，显示有关当前选定游戏对象、资产或项目设置的信息，允许您检查和编辑值。更多信息
请参阅术语表窗口，请输入radial-progress在“名称”框中。
在“检查器”窗口中，在“进度”框中输入不同的值。中的百分比视口用户在屏幕上应用的可见区域。
在术语表中查看更改，绿色进度环将调整大小。

创建逻辑以使用动态值更新进度

创建一个 C# MonoBehaviour 脚本来更新Progress控件的属性，其中包含用于演示目的的动态值。在radial-progress文件夹中，创建一个名为RadialProgressComponent.cs内容如下：

using MyUILibrary;
using UnityEngine;
using UnityEngine.UIElements;

[RequireComponent(typeof(UIDocument))]
public class RadialProgressComponent : MonoBehaviour
{
    RadialProgress m_RadialProgress;

    void OnEnable()
    {
        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;
    }
}

在运行时测试进度指示器

在 Unity 中，选择“游戏对象”>“UI 工具包”>“UI 文档”。
在“层次结构”窗口中选择 UIDocument。
将RadialProgressComponent.cs添加为 UIDocument 的组件游戏对象Unity 场景中的基本对象，可以表示角色、道具、风景、相机、航路点等。游戏对象的功能由附加到它的组件定义。更多信息
请参阅术语表.
进入播放模式。进度指示器出现在场景场景包含游戏的环境和菜单。将每个唯一的场景文件视为一个独特的关卡。在每个场景中，你放置你的环境、障碍物和装饰品，基本上是将你的游戏设计和构建成碎片。更多信息
请参阅术语表，进度环和值动态变化。

其他资源

创建自定义控件

使用 Painter2D API 创建径向进度指示器

并行细分

手册

使用 Mesh API 创建径向进度指示器

示例概述

先决条件

创建径向进度指示器及其自定义网格

创建自定义网格

设置自定义控件的样式

在 UI 文档中使用自定义控件并测试

创建逻辑以使用动态值更新进度

在运行时测试进度指示器

其他资源