c#代碼實現軸向鏤空效果

適用說明：

本文僅適用於模型比較簡單，網格沿軸向分佈的模型，如正方體，長方體等。

效果說明：

模型的貼圖是完整的，但需要動態的按網格數來創建貼圖實現指定效果，如下：

（鏤空前）

（鏤空後）

實現步驟：

一、獲取網格數據

[System.Serializable]
public struct MeshStruct  {
    public int[] triangles;       // 網格的三角形
    public Vector2[] uvs;         // 網格的UV座標
    public MeshStruct(int[] triangles,Vector2[] uvs)
    {
        this.vertices = vertices;
        this.triangles = triangles;
        this.uvs = uvs;
    }
}

以上結構體說明需要獲取到的網格信息

二、限制獲取顏色區域

using UnityEngine;
using UnityEngine.UI;
using UnityEngine.Events;
using System.Collections.Generic;

public static class TextureUtility
{
    /// <summary>
    /// 利用貼圖獲取網格貼圖
    /// </summary>
    /// <param name="meshStruct"></param>
    /// <param name="texture"></param>
    /// <returns></returns>
    public static Texture2D GetLineTexture(MeshStruct meshData, Texture2D texture)
    {
        int width = texture.width;
        int height = texture.height;
        Texture2D newTexture = new Texture2D(width, height, TextureFormat.ARGB32, false);
        newTexture.alphaIsTransparency = true;
        Color[] colors = new Color[width * height];
        for (int i = 0; i < colors.Length; i++){
            colors[i] = Color.clear;
        }
        newTexture.SetPixels(colors);

        for (int k = 0; k < meshData.triangles.Length - 2; k += 3)
        {
            Vector2[] _uvs = new Vector2[3];
            int tID1 = meshData.triangles[k];
            int tID2 = meshData.triangles[k + 1];
            int tID3 = meshData.triangles[k + 2];

            _uvs[0] = meshData.uvs[tID1];
            _uvs[1] = meshData.uvs[tID2];
            _uvs[2] = meshData.uvs[tID3];

            for (int i = 0; i < _uvs.Length; ++i)
            {
                for (int j = i + 1; j < _uvs.Length; ++j)
                {
                    if (_uvs[i].x == _uvs[j].x || _uvs[i].y == _uvs[j].y)//軸向
                    {
                        float uvx1 = _uvs[i].x;
                        float uvy1 = _uvs[i].y;
                        float uvx2 = _uvs[j].x;
                        float uvy2 = _uvs[j].y;

                        int px1 = (int)(uvx1 * width);
                        int py1 = (int)(uvy1 * height);
                        int px2 = (int)(uvx2 * width);
                        int py2 = (int)(uvy2 * height);

                        int minpx = px1 < px2 ? px1 : px2;
                        int minpy = py1 < py2 ? py1 : py2;

                        int pw = Mathf.FloorToInt(Mathf.Abs((uvx1 - uvx2) * width));
                        int ph = Mathf.FloorToInt(Mathf.Abs((uvy1 - uvy2) * height));

                        for (int m = 0; m <= ph; m++)
                        {
                            for (int n = 0; n <= pw; n++)
                            {
                                Color colorline = texture.GetPixel(minpx + n, minpy + m);
                                newTexture.SetPixel(minpx + n, minpy + m, colorline);
                            }
                        }
                    }
                }
            }
        }
        newTexture.Apply();
        return newTexture;
    }
}

三、修改材質球shader類型

由於standard材質球不支持雙面顯示效果，這裏使用這個Shader:

Particles/Alpha Blended

    public static Material GetParticalMaterial(Texture texture)
    {
        // Unity has a built-in shader that is useful for drawing
        // simple colored things.
        Shader shader = Shader.Find("Particles/Alpha Blended");
        Material particMat = new Material(shader);
        particMat.mainTexture = texture;
        return particMat;
    }