Unity3d中，terrain还是比较耗的，DrawCall数也比较多，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
代码还有诸多问题，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 DevDebug.Log("Selection.objects.Length <= 0");
12 return;
13 }
14
15 var terrainObj = Selection.objects[0] as GameObject;
16 if (terrainObj == null)
17 {
18 DevDebug.Log("terrainObj == null");
19 return;
20 }
21
22 var terrain = terrainObj.GetComponent<Terrain>();
23 if (terrain == null)
24 {
25 DevDebug.Log("terrain == null");
26 return;
27 }
28
29 var terrainData = terrain.terrainData;
30 if (terrainData == null)
31 {
32 DevDebug.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;
108 mesh.Optimize();
109
110 // 地形渲染 [dev] 目前不支持光照，有待改善
111 var mat = new Material(Shader.Find("Custom/TerrainDiffuse"));
112 for (int i = 0; i < terrainData.splatPrototypes.Length; i++)
113 {
114 var sp = terrainData.splatPrototypes[i];
115 mat.SetTexture("_Texture" + i, sp.texture);
116 }
117
118 string transName = "[dev]MeshFromTerrainData";
119 var t = terrainObj.transform.parent.Find(transName);
120 if (t == null)
121 {
122 GameObject go = new GameObject(transName, typeof(MeshFilter), typeof(MeshRenderer), typeof(MeshCollider));
123 t = go.transform;
124 }
125
126 t.parent = terrainObj.transform.parent;
127 t.position = terrainObj.transform.position;
128 t.gameObject.layer = terrainObj.layer;
129 t.GetComponent<MeshFilter>().sharedMesh = mesh;
130 t.GetComponent<MeshCollider>().sharedMesh = mesh;
131 t.GetComponent<MeshRenderer>().sharedMaterial = mat;
132
133 t.gameObject.SetActive(true);
134 terrainObj.SetActive(false);
135 }
136 }
TerrainToMeshConverter
渲染地形的shader如下：
1 Shader "Custom/TerrainDiffuse"
2 {
3 Properties
4 {
5 _Texture0 ("Texture 1", 2D) = "white" {}
6 _Texture1 ("Texture 2", 2D) = "white" {}
7 _Texture2 ("Texture 3", 2D) = "white" {}
8 _Texture3 ("Texture 4", 2D) = "white" {}
9 }
10
11 SubShader
12 {
13 Tags { "RenderType"="Opaque" }
14 LOD 200
15
16 Pass
17 {
18 CGPROGRAM
19 #pragma vertex Vert
20 #pragma fragment Frag
21
22 sampler2D _Texture0;
23 sampler2D _Texture1;
24 sampler2D _Texture2;
25 sampler2D _Texture3;
26
27 struct VertexData
28 {
29 float4 Pos : POSITION;
30 float4 Tangent : TANGENT;
31 float2 uv : TEXCOORD0;
32 };
33
34 struct V2F
35 {
36 float4 Pos : SV_POSITION;
37 float4 Color : COLOR;
38 float2 uv : TEXCOORD0;
39 };
40
41 V2F Vert(VertexData v)
42 {
43 V2F o;
44 o.Pos = mul(UNITY_MATRIX_MVP, v.Pos);
45 o.Color = v.Tangent;
46 o.uv = v.uv;
47 return o;
48 }
49
50 float4 Frag(V2F i) : COLOR
51 {
52 float4 t0 = tex2D(_Texture0, i.uv);
53 float4 t1 = tex2D(_Texture1, i.uv);
54 float4 t2 = tex2D(_Texture2, i.uv);
55 float4 t3 = tex2D(_Texture3, i.uv);
56
57 return t0 * i.Color.x + t1 * i.Color.y + t2 * i.Color.z + t3 * i.Color.w;
58 }
59
60 ENDCG
61 }
62 }
63 }
Shader
生成的mesh与原terrain对比如下，左边为mesh，右边为terrain:
性能对比如下：
mesh:
terrain:
转载请注明出处：
http://www.cnblogs.com/jietian331/p/5831062.html
时间： 2024-10-13 15:24:03