Unity3d之将terrain转化成mesh

Unity3d中，terrain还是比较耗的，为了优化性能，可能需要将terrain转化成mesh。

现提供一工具，思路是根据terrain高度图生成mesh等。

可参考： http://wiki.unity3d.com/index.php?title=TerrainObjExporter

转载请注明出处：

 http://www.cnblogs.com/jietian331/p/5831062.html

 

代码如下：

  1 using UnityEditor;
  2 using UnityEngine;
  3 
  4 public class TerrainToMeshConverter : ScriptableObject
  5 {
  6     [MenuItem("Custom/Convert terrain to mesh")]
  7     static void Init()
  8     {
  9         if (Selection.objects.Length <= 0)
 10         {
 11             Debug.Log("Selection.objects.Length <= 0");
 12             return;
 13         }
 14 
 15         var terrainObj = Selection.objects[0] as GameObject;
 16         if (terrainObj == null)
 17         {
 18             Debug.Log("terrainObj == null");
 19             return;
 20         }
 21 
 22         var terrain = terrainObj.GetComponent<Terrain>();
 23         if (terrain == null)
 24         {
 25             Debug.Log("terrain == null");
 26             return;
 27         }
 28 
 29         var terrainData = terrain.terrainData;
 30         if (terrainData == null)
 31         {
 32             Debug.Log("terrainData == null");
 33             return;
 34         }
 35 
 36         int vertexCountScale = 4;       // [dev] 将顶点数稀释 vertexCountScale*vertexCountScale 倍
 37         int w = terrainData.heightmapWidth;
 38         int h = terrainData.heightmapHeight;
 39         Vector3 size = terrainData.size;
 40         float[, ,] alphaMapData = terrainData.GetAlphamaps(0, 0, terrainData.alphamapWidth, terrainData.alphamapHeight);
 41         Vector3 meshScale = new Vector3(size.x / (w - 1f) * vertexCountScale, 1, size.z / (h - 1f) * vertexCountScale);
 42         Vector2 uvScale = new Vector2(1f / (w - 1f), 1f / (h - 1f)) * vertexCountScale * (size.x / terrainData.splatPrototypes[0].tileSize.x);     // [dev] 此处有问题，若每个图片大小不一，则出问题。日后改善
 43 
 44         w = (w - 1) / vertexCountScale + 1;
 45         h = (h - 1) / vertexCountScale + 1;
 46         Vector3[] vertices = new Vector3[w * h];
 47         Vector2[] uvs = new Vector2[w * h];
 48         Vector4[] alphasWeight = new Vector4[w * h];            // [dev] 只支持4张图片
 49 
 50         // 顶点，uv，每个顶点每个图片所占比重
 51         for (int i = 0; i < w; i++)
 52         {
 53             for (int j = 0; j < h; j++)
 54             {
 55                 int index = j * w + i;
 56                 float z = terrainData.GetHeight(i * vertexCountScale, j * vertexCountScale);
 57                 vertices[index] = Vector3.Scale(new Vector3(i, z, j), meshScale);
 58                 uvs[index] = Vector2.Scale(new Vector2(i, j), uvScale);
 59 
 60                 // alpha map
 61                 int i2 = (int)(i * terrainData.alphamapWidth / (w - 1f));
 62                 int j2 = (int)(j * terrainData.alphamapHeight / (h - 1f));
 63                 i2 = Mathf.Min(terrainData.alphamapWidth - 1, i2);
 64                 j2 = Mathf.Min(terrainData.alphamapHeight - 1, j2);
 65                 var alpha0 = alphaMapData[j2, i2, 0];
 66                 var alpha1 = alphaMapData[j2, i2, 1];
 67                 var alpha2 = alphaMapData[j2, i2, 2];
 68                 var alpha3 = alphaMapData[j2, i2, 3];
 69                 alphasWeight[index] = new Vector4(alpha0, alpha1, alpha2, alpha3);
 70             }
 71         }
 72 
 73         /*
 74          * 三角形
 75          *     b       c
 76          *      *******
 77          *      *   * *
 78          *      * *   *
 79          *      *******
 80          *     a       d
 81          */
 82         int[] triangles = new int[(w - 1) * (h - 1) * 6];
 83         int triangleIndex = 0;
 84         for (int i = 0; i < w - 1; i++)
 85         {
 86             for (int j = 0; j < h - 1; j++)
 87             {
 88                 int a = j * w + i;
 89                 int b = (j + 1) * w + i;
 90                 int c = (j + 1) * w + i + 1;
 91                 int d = j * w + i + 1;
 92 
 93                 triangles[triangleIndex++] = a;
 94                 triangles[triangleIndex++] = b;
 95                 triangles[triangleIndex++] = c;
 96 
 97                 triangles[triangleIndex++] = a;
 98                 triangles[triangleIndex++] = c;
 99                 triangles[triangleIndex++] = d;
100             }
101         }
102 
103         Mesh mesh = new Mesh();
104         mesh.vertices = vertices;
105         mesh.uv = uvs;
106         mesh.triangles = triangles;
107         mesh.tangents = alphasWeight;       // 将地形纹理的比重写入到切线中
108 
109         string transName = "[dev]MeshFromTerrainData";
110         var t = terrainObj.transform.parent.Find(transName);
111         if (t == null)
112         {
113             GameObject go = new GameObject(transName, typeof(MeshFilter), typeof(MeshRenderer), typeof(MeshCollider));
114             t = go.transform;
115         }
116 
117         // 地形渲染
118         MeshRenderer mr = t.GetComponent<MeshRenderer>();
119         Material mat = mr.sharedMaterial;
120         if (!mat)
121             mat = new Material(Shader.Find("Custom/Environment/TerrainSimple"));
122 
123         for (int i = 0; i < terrainData.splatPrototypes.Length; i++)
124         {
125             var sp = terrainData.splatPrototypes[i];
126             mat.SetTexture("_Texture" + i, sp.texture);
127         }
128 
129         t.parent = terrainObj.transform.parent;
130         t.position = terrainObj.transform.position;
131         t.gameObject.layer = terrainObj.layer;
132         t.GetComponent<MeshFilter>().sharedMesh = mesh;
133         t.GetComponent<MeshCollider>().sharedMesh = mesh;
134         mr.sharedMaterial = mat;
135 
136         t.gameObject.SetActive(true);
137         terrainObj.SetActive(false);
138 
139         Debug.Log("Convert terrain to mesh finished!");
140     }
141 }

TerrainToMeshConverter