LineUtility.Simplify

参数

描述

通过删除位于指定容差范围内的点，生成原始线条的简化版本。

例如，你可以使用此函数缩减由数千个点构成的复杂线条。可以将该线条缩减至数百个甚至更少的点，同时仍然保持与原始线条非常接近的形状。你可以通过调整容差（较高的容差值会导致生成线条中的点较少）来生成同一线条的多个不同细节级别的版本。然后，可以使用 LODGroup 系统显示生成的线条。

Simplify 算法基于Ramer Douglas Peucker 算法；它创建一条非常接近所提供线条但点较少的线条（由容差值确定）。

注释：该函数能够处理大量的点，因为它是非递归的。此函数的 2D 版本比此函数的性能要好，因为它使用了一种更简单的点评估方式。

其他资源：LineRenderer.Simplify。

以下示例演示如何将线简化应用到现有的线中。

using System.Collections.Generic;
using System.Linq;
using UnityEngine;

// This example shows how to apply line simplification to a line that already contains points.
[RequireComponent(typeof(LineRenderer))]
public class SimpleExampleLineUtility : MonoBehaviour
{
    public float tolerance = 1;
    void Start()
    {
        // Get the points.
        var lineRenderer = GetComponent<LineRenderer>();
        int pointsBefore = lineRenderer.positionCount;
        var points = new Vector3[pointsBefore];
        lineRenderer.GetPositions(points);

        // Simplify.
        var simplifiedPoints = new List<Vector3>();
        LineUtility.Simplify(points.ToList(), tolerance, simplifiedPoints);

        // Assign back to the line renderer.
        lineRenderer.positionCount = simplifiedPoints.Count;
        lineRenderer.SetPositions(simplifiedPoints.ToArray());

        Debug.Log("Line reduced from " + pointsBefore + " to " + lineRenderer.positionCount);
    }
}

以下示例演示如何使用 pointsToKeep 参数返回索引列表。该列表随后可用于简化保留该列表中点的线段。仍可向所得简化线段中添加其他点。

using System.Collections.Generic;
using System.Linq;
using UnityEngine;

// This example shows how to use the pointsToKeep parameter to generate a new simplified version of the line.
[RequireComponent(typeof(LineRenderer))]
public class SimpleExampleLineUtilityPointsToKeep : MonoBehaviour
{
    public float tolerance = 1;
    void Start()
    {
        // Get the points.
        var lineRenderer = GetComponent<LineRenderer>();
        int pointsBefore = lineRenderer.positionCount;
        var points = new Vector3[pointsBefore];
        lineRenderer.GetPositions(points);

        // Simplify.
        var pointsToKeep = new List<int>();
        LineUtility.Simplify(points.ToList(), tolerance, pointsToKeep);

        var simplifiedPoints = new Vector3[pointsToKeep.Count];
        for (int i = 0; i < simplifiedPoints.Length; ++i)
        {
            simplifiedPoints[i] = points[pointsToKeep[i]];
        }

        // Assign back to the line renderer.
        lineRenderer.positionCount = simplifiedPoints.Length;
        lineRenderer.SetPositions(simplifiedPoints);

        Debug.Log("Line reduced from " + pointsBefore + " to " + lineRenderer.positionCount);
    }
}

本示例生成一条正弦波形状的线段，并提供一个 GUI 来自定义线段生成和简化参数。

using System.Collections.Generic;
using UnityEngine;

// This example creates a sine wave and then simplifies it using the LineUtility.
// The parameters can be adjusted through an in game GUI to allow for experimentation.
[RequireComponent(typeof(LineRenderer))]
public class LineUtilityExample : MonoBehaviour
{
    public int numberOfPoints = 1000;
    public float length = 50;
    public float waveHeight = 10;
    public float tolerance = 0.1f;

    private LineRenderer lineRenderer;
    private List<Vector3> points = new List<Vector3>(); // Generated points before LineOptimizer is used.
    private List<Vector3> simplifiedPoints = new List<Vector3>(); // Simplified points after LineOptimizer is used.

    public void Start()
    {
        lineRenderer = GetComponent<LineRenderer>();
    }

    // Generates the sine wave points.
    public void GeneratePoints()
    {
        points.Clear();
        float halfWaveHeight = waveHeight * 0.5f;
        float step = length / numberOfPoints;
        for (int i = 0; i < numberOfPoints; ++i)
        {
            points.Add(new Vector3(i * step, Mathf.Sin(i * step) * halfWaveHeight, 0));
        }
    }

    // Simplify the line using the LineOptimizer.
    public void SimplifyLine()
    {
        simplifiedPoints.Clear();
        LineUtility.Simplify(points, tolerance, simplifiedPoints);
        lineRenderer.positionCount = simplifiedPoints.Count;
        lineRenderer.SetPositions(simplifiedPoints.ToArray());
    }

    // Draw a simple GUI slider with a label.
    private static float GUISlider(string label, float value, float min, float max)
    {
        GUILayout.BeginHorizontal(GUILayout.Width(Screen.width / 2.0f));
        GUILayout.Label(label + "(" + value + ") :", GUILayout.Width(150));
        var val = GUILayout.HorizontalSlider(value, min, max);
        GUILayout.EndHorizontal();
        return val;
    }

    public void OnGUI()
    {
        GUILayout.Label("LineUtility.Simplify", GUI.skin.box);

        // We use GUI.changed to detect if a value was changed via the GUI, if it has we can then re-generate the points and simplify the line again.
        GUI.changed = false;

        numberOfPoints = (int)GUISlider("Number of Points", numberOfPoints, 0, 1000);
        length = GUISlider("Length", length, 0, 100);
        waveHeight = GUISlider("Wave Height", waveHeight, 0, 100);
        if (GUI.changed)
            GeneratePoints();

        tolerance = GUISlider("Simplify Tolerance", tolerance, 0, 2);
        if (GUI.changed)
            SimplifyLine();

        float percentRemoved = 100.0f - ((float)lineRenderer.positionCount / numberOfPoints) * 100.0f;
        if (tolerance > 0.0f)
            GUILayout.Label("Points after simplification: " + lineRenderer.positionCount + "(Removed " + percentRemoved.ToString("##.##") + "%)");
    }
}