1using UnityEngine;
2using UnityEditor;
3
4public class Object2Terrain : EditorWindow
5{
6
7    [MenuItem("Terrain/Object to Terrain", false, 2000)]
8    static void OpenWindow()
9    {
10
11        EditorWindow.GetWindow<Object2Terrain>(true);
12    }
13
14    private int resolution = 512;
15    private Vector3 addTerrain;
16    int bottomTopRadioSelected = 0;
17    static string[] bottomTopRadio = new string[] { "Bottom Up", "Top Down" };
18    private float shiftHeight = 0f;
19
20    void OnGUI()
21    {
22
23        resolution = EditorGUILayout.IntField("Resolution", resolution);
24        addTerrain = EditorGUILayout.Vector3Field("Add terrain", addTerrain);
25        shiftHeight = EditorGUILayout.Slider("Shift height", shiftHeight, -1f, 1f);
26        bottomTopRadioSelected = GUILayout.SelectionGrid(bottomTopRadioSelected, bottomTopRadio, bottomTopRadio.Length, EditorStyles.radioButton);
27
28        if (GUILayout.Button("Create Terrain"))
29        {
30
31            if (Selection.activeGameObject == null)
32            {
33
34                EditorUtility.DisplayDialog("No object selected", "Please select an object.", "Ok");
35                return;
36            }
37
38            else
39            {
40
41                CreateTerrain();
42            }
43        }
44    }
45
46    delegate void CleanUp();
47
48    void CreateTerrain()
49    {
50
51        //fire up the progress bar
52        ShowProgressBar(1, 100);
53
54        TerrainData terrain = new TerrainData();
55        terrain.heightmapResolution = resolution;
56        GameObject terrainObject = Terrain.CreateTerrainGameObject(terrain);
57
58        Undo.RegisterCreatedObjectUndo(terrainObject, "Object to Terrain");
59
60        MeshCollider collider = Selection.activeGameObject.GetComponent<MeshCollider>();
61        CleanUp cleanUp = null;
62
63        //Add a collider to our source object if it does not exist.
64        //Otherwise raycasting doesn't work.
65        if (!collider)
66        {
67
68            collider = Selection.activeGameObject.AddComponent<MeshCollider>();
69            cleanUp = () => DestroyImmediate(collider);
70        }
71
72        Bounds bounds = collider.bounds;
73        float sizeFactor = collider.bounds.size.y / (collider.bounds.size.y + addTerrain.y);
74        terrain.size = collider.bounds.size + addTerrain;
75        bounds.size = new Vector3(terrain.size.x, collider.bounds.size.y, terrain.size.z);
76
77        // Do raycasting samples over the object to see what terrain heights should be
78        float[,] heights = new float[terrain.heightmapWidth, terrain.heightmapHeight];
79        Ray ray = new Ray(new Vector3(bounds.min.x, bounds.max.y + bounds.size.y, bounds.min.z), -Vector3.up);
80        RaycastHit hit = new RaycastHit();
81        float meshHeightInverse = 1 / bounds.size.y;
82        Vector3 rayOrigin = ray.origin;
83
84        int maxHeight = heights.GetLength(0);
85        int maxLength = heights.GetLength(1);
86
87        Vector2 stepXZ = new Vector2(bounds.size.x / maxLength, bounds.size.z / maxHeight);
88
89        for (int zCount = 0; zCount < maxHeight; zCount++)
90        {
91
92            ShowProgressBar(zCount, maxHeight);
93
94            for (int xCount = 0; xCount < maxLength; xCount++)
95            {
96
97                float height = 0.0f;
98
99                if (collider.Raycast(ray, out hit, bounds.size.y * 3))
100                {
101
102                    height = (hit.point.y - bounds.min.y) * meshHeightInverse;
103                    height += shiftHeight;
104
105                    //bottom up
106                    if (bottomTopRadioSelected == 0)
107                    {
108
109                        height *= sizeFactor;
110                    }
111
112                    //clamp
113                    if (height < 0)
114                    {
115
116                        height = 0;
117                    }
118                }
119
120                heights[zCount, xCount] = height;
121                rayOrigin.x += stepXZ[0];
122                ray.origin = rayOrigin;
123            }
124
125            rayOrigin.z += stepXZ[1];
126            rayOrigin.x = bounds.min.x;
127            ray.origin = rayOrigin;
128        }
129
130        terrain.SetHeights(0, 0, heights);
131
132        EditorUtility.ClearProgressBar();
133
134        if (cleanUp != null)
135        {
136
137            cleanUp();
138        }
139    }
140
141    void ShowProgressBar(float progress, float maxProgress)
142    {
143
144        float p = progress / maxProgress;
145        EditorUtility.DisplayProgressBar("Creating Terrain...", Mathf.RoundToInt(p * 100f) + " %", p);
146    }
147}