Unity畫貝塞爾曲線自定義圖片組件

頭一回寫這個文章，也是就分享一點自己的學習心得，并且記錄下自己做過的這個功能，

事實上我這也是借鑒了大佬的代碼，統籌琢磨出來的，比較初級，但是有用，

話不多說，上效果圖：

如圖所見，展現出來的功能組件很簡單，就是一個繼承了Image并且多加了幾個變數的自定義組件 ，實作的就是右邊將圖片作為元素繪制成一條貝塞爾曲線，

控制點串列中的點資料我做的還不夠智能，暫時用第一個和最后一個表示這條線的起點和終點，而其他的點都是這條貝塞爾曲線的極點了，

“密集度 mesh數量”可以看成是要生成多少個圖片元素

“mesh寬度”可以看成你要生成圖片元素的大小

反正就那個意思，很簡單，我就不多啰嗦了，看見這篇文章的朋友完全可以直接下來用，大家也可以根據我的代碼進行拓展的，看懂原來的垃圾代碼就好了嘿嘿~（手都滑稽）

public static class Bezier
{
    /// <summary>
    /// 獲取繪制點
    /// </summary>
    /// <param name="controlPoints">控制點串列</param>
    /// <param name="density">密度</param>
    /// <returns></returns>
    public static Vector3[] GetPointList(List<Vector2> controlPoints, int density)
    {
        List<Vector3> points = new List<Vector3>();
        for(int i = 0; i <= density; i++)
        {
            points.Add(BezierMath(i / (float)density, controlPoints.Count - 1, controlPoints));
        }
        return points.ToArray();
    }

    /// <summary>
    /// 貝塞爾曲線的函式
    /// </summary>
    /// <param name="t">分段引數</param>
    /// <param name="lineNum">線段數量</param>
    /// <param name="controlPoints">錨點串列</param>
    /// <returns></returns>
    public static Vector2 BezierMath(float t, int lineNum, List<Vector2> controlPoints)
    {
        Vector2 result = new Vector2();

        for (int i = 0; i <= lineNum; i++)
        {
            float temp = BaseBezier(t, i, lineNum);
            result.x += controlPoints[i].x * temp;
            result.y += controlPoints[i].y * temp;
        }

        return result;
    }
    /// <summary>
    /// 貝塞爾基函式
    /// </summary>
    /// <param name="t">引數</param>
    /// <param name="index">線段序號</param>
    /// <param name="lineNum">線段數量</param>
    /// <returns></returns>
    public static float BaseBezier(float t, int index, int lineNum)
    {
        float result = Factorial(lineNum) * Mathf.Pow(t, index) * Mathf.Pow(1 - t, lineNum - index) / (Factorial(index) * Factorial(lineNum - index));
        return result;
    }

    /// <summary>
    /// Factorial 階乘
    /// </summary>
    /// <param name="step"></param>
    /// <returns></returns>
    public static int Factorial(int step)
    {
        int result = 1;
        for (int j = step; j > 1; j--)
        {
            result *= j;
        }
        return result;
    }
}

public class BezierMeshImage : Image
{
    /// <summary> 密集度 mesh數量 </summary>
    public int density = 50;
    /// <summary> mesh 寬度  </summary>
    public float width;
    /// <summary> 控制點串列 </summary>
    public List<Vector2> controlList = new List<Vector2>();

    /// <summary> 貝塞爾點陣列 </summary>
    Vector3[] bezierPoints;

    protected override void OnPopulateMesh(VertexHelper vh)
    {
        bezierPoints = Bezier.GetPointList(controlList, density);
        vh.Clear();
        for (int index = 0; index < bezierPoints.Length; index++)
        {
            Vector3 baseVector = bezierPoints[index];
            var i = index * 4;
            vh.AddVert(baseVector + new Vector3(-width/2, -width/2, 1), color, new Vector2(0f, 0f));
            vh.AddVert(baseVector + new Vector3(-width/2, width/2, 1), color, new Vector2(0f, 1f));
            vh.AddVert(baseVector + new Vector3(width/2, width/2, 1), color, new Vector2(1f, 1f));
            vh.AddVert(baseVector + new Vector3(width/2, -width/2, 1), color, new Vector2(1f, 0f));
            vh.AddTriangle(i, i + 1, i + 2);
            vh.AddTriangle(i + 2, i + 3, i);
        }
    }
}

[CustomEditor(typeof(BezierMeshImage))] // 定義子類的編輯器擴展
public class BezierMeshImageEditor : ImageEditor
{
    private BezierMeshImage be;
    public List<Vector2> pointList;
    public static bool isOpenList;
    public override void OnInspectorGUI()
    {
        base.OnInspectorGUI();
        be = (BezierMeshImage)base.target;
        //be.controlV2 = EditorGUILayout.Vector2Field("控制點坐標", be.controlV2);
        be.density = EditorGUILayout.IntField("密集度 mesh數量", be.density);
        be.width = EditorGUILayout.FloatField("mesh 寬度 ", be.width);
        pointList = be.controlList;
        isOpenList = EditorGUILayout.Foldout(isOpenList, "控制點串列");
        if(isOpenList)
        {
            for(int i = 0; i < pointList.Count; i++)
            {
                pointList[i] = EditorGUILayout.Vector2Field(name, pointList[i]);
            }
            EditorGUILayout.BeginHorizontal();
            if (GUILayout.Button("+"))
            {
                Vector2 point = new Vector2();
                point = EditorGUILayout.Vector2Field(name, point);
                pointList.Add(point);
            }
            if (GUILayout.Button("-"))
            {
                if (pointList.Count > 0)
                    pointList.RemoveAt(pointList.Count - 1);
            }
            EditorGUILayout.EndHorizontal();            
        }
        be.controlList = pointList;
        if (HasPreviewGUI())
        {
            be.enabled = false;
            be.enabled = true;
        }
    }

}