Unity 烘焙材质到单一贴图的脚本

原地址：http://www.cocoachina.com/gamedev/gameengine/2011/0406/2756.html

这个脚本由 CocoaChina 版主 “四角钱” 分享，可以将复杂的材质（比如有法线贴图的材质）进行"烘焙"，转变为单一的贴图。可用来将 Unity 的游戏移植到移动平台时候使用。请将脚本放 Editor 文件夹里，使用时选择一个 Material 材质，然后在菜单种"Custom/Bake Material"打开并调整照明和其他参数，点击Bake按钮就会生成一个单一的贴图。

class BakeMaterialSettings
{
    private static var kEditorPrefsName = "BakeMaterialSettings";

    static var kBakingLayerShouldBeUnusedInScene = 30;
    static var kStandardTexNames = new Array ("_MainTex", "_BumpMap", "_Detail", "_ParallaxMap", "_Parallax");

    var bakeAlpha = false;
    var bakeMainTexAsWhite = false;
    var minTextureResolution = 8;
    var maxTextureResolution = 2048;

    var emptyScene = false;
    var useCustomLights = false;
    var ambient = Color.black;

    static var kLights = 3;
    var enableLight = new boolean[kLights];
    var colorLight = new Color[kLights];
    var dirLight = new Vector2[kLights];

    function BakeMaterialSettings ()
    {
        Load ();
    }

    function Load ()
    {
        bakeAlpha = EditorPrefs.GetBool(kEditorPrefsName + ".bakeAlpha");
        bakeMainTexAsWhite = EditorPrefs.GetBool(kEditorPrefsName + ".bakeMainTexAsWhite");
        minTextureResolution = EditorPrefs.GetInt(kEditorPrefsName + ".minTextureResolution", 8);
        maxTextureResolution = EditorPrefs.GetInt(kEditorPrefsName + ".maxTextureResolution", 2048);

        emptyScene = EditorPrefs.GetBool(kEditorPrefsName + ".emptyScene");
        useCustomLights = EditorPrefs.GetBool(kEditorPrefsName + ".useCustomLights");
        ambient.r = EditorPrefs.GetFloat(kEditorPrefsName + ".ambient.r");
        ambient.g = EditorPrefs.GetFloat(kEditorPrefsName + ".ambient.g");
        ambient.b = EditorPrefs.GetFloat(kEditorPrefsName + ".ambient.b");
        ambient.a = EditorPrefs.GetFloat(kEditorPrefsName + ".ambient.a", 1.0f);

        for (var q = 0; q < kLights; ++q)
        {
            enableLight[q] = EditorPrefs.GetBool(kEditorPrefsName + ".enableLight" + q);
            colorLight[q].r = EditorPrefs.GetFloat(kEditorPrefsName + ".color.r" + q, 0.5f);
            colorLight[q].g = EditorPrefs.GetFloat(kEditorPrefsName + ".color.g" + q, 0.5f);
            colorLight[q].b = EditorPrefs.GetFloat(kEditorPrefsName + ".color.b" + q, 0.5f);
            colorLight[q].a = EditorPrefs.GetFloat(kEditorPrefsName + ".color.a" + q, 1.0f);
            dirLight[q].x = EditorPrefs.GetFloat(kEditorPrefsName + ".dir.x" + q);
            dirLight[q].y = EditorPrefs.GetFloat(kEditorPrefsName + ".dir.y" + q);
        }
    }

    function Save ()
    {
        EditorPrefs.SetBool(kEditorPrefsName + ".bakeAlpha", bakeAlpha);
        EditorPrefs.SetBool(kEditorPrefsName + ".bakeMainTexAsWhite", bakeMainTexAsWhite);
        EditorPrefs.SetInt(kEditorPrefsName + ".minTextureResolution", minTextureResolution);
        EditorPrefs.SetInt(kEditorPrefsName + ".maxTextureResolution", maxTextureResolution);

        EditorPrefs.GetBool(kEditorPrefsName + ".emptyScene", emptyScene);
        EditorPrefs.SetBool(kEditorPrefsName + ".useCustomLights", useCustomLights);
        EditorPrefs.SetFloat(kEditorPrefsName + ".ambient.r", ambient.r);
        EditorPrefs.SetFloat(kEditorPrefsName + ".ambient.g", ambient.g);
        EditorPrefs.SetFloat(kEditorPrefsName + ".ambient.b", ambient.b);
        EditorPrefs.SetFloat(kEditorPrefsName + ".ambient.a", ambient.a);

        for (var q = 0; q < kLights; ++q)
        {
            EditorPrefs.SetBool(kEditorPrefsName + ".enableLight" + q, enableLight[q]);
            EditorPrefs.SetFloat(kEditorPrefsName + ".color.r" + q, colorLight[q].r);
            EditorPrefs.SetFloat(kEditorPrefsName + ".color.g" + q, colorLight[q].g);
            EditorPrefs.SetFloat(kEditorPrefsName + ".color.b" + q, colorLight[q].b);
            EditorPrefs.SetFloat(kEditorPrefsName + ".color.a" + q, colorLight[q].a);
            EditorPrefs.SetFloat(kEditorPrefsName + ".dir.x" + q, dirLight[q].x);
            EditorPrefs.SetFloat(kEditorPrefsName + ".dir.y" + q, dirLight[q].y);
        }
    }
}

class BakeMaterial extends EditorWindow
{
    private static var kMateriBakeNodeName = "__MateriaBakeSetup";
    private static var kWindowMinSize = Vector2 (300, 386);

    private static var settings : BakeMaterialSettings;
    private static var visible : boolean = false;

    private var camera : GameObject;
    private var plane : GameObject;
    private var previewTexture : Texture;
    private var lights : GameObject[] = new GameObject[BakeMaterialSettings.kLights];
    private var stateChanged = false;

    private var texViewScrollPosition = Vector2.zero;
    private var lastMaterial : Material;

    private var originalScene = "";

    private var scheduleBakeOnNextUpdate = false;

    private function SetupScene ()
    {
        DestroyScene ();
        var oldGo = GameObject.Find(kMateriBakeNodeName);
        if (oldGo)
            DestroyImmediate (oldGo);
        camera = new GameObject (kMateriBakeNodeName, Camera);
        plane = GameObject.CreatePrimitive (PrimitiveType.Plane);

        var cam = camera;
        cam.camera.backgroundColor = Color.black;
        cam.camera.clearFlags = CameraClearFlags.SolidColor;
        cam.camera.orthographic = true;
        cam.camera.orthographicSize = 5.0;
        cam.camera.cullingMask = 1 << settings.kBakingLayerShouldBeUnusedInScene;

        plane.transform.parent = cam.transform;
        plane.transform.position = Vector3.forward * 10.0;
        plane.transform.rotation = Quaternion.Euler (0, 0, 180) * Quaternion.Euler (-90, 0, 0);
        plane.layer = settings.kBakingLayerShouldBeUnusedInScene;

        for (var l in lights)
        {
            l = new GameObject ("Light", Light);
            l.light.type = LightType.Directional;
            l.light.cullingMask = 1 << settings.kBakingLayerShouldBeUnusedInScene;
            l.transform.parent = cam.transform;
            l.active = false;
        }
    }

    private function UpdateScene (m : Material)
    {
        for (q = 0; q < settings.kLights; ++q)
        {
            lights[q].active = settings.useCustomLights & settings.enableLight[q];
            lights[q].light.color = settings.colorLight[q];
            lights[q].transform.rotation =
                Quaternion.AngleAxis(settings.dirLight[q].x, Vector3.up) *
                Quaternion.AngleAxis(settings.dirLight[q].y, Vector3.right);
        }

        if (settings.useCustomLights)
            RenderSettings.ambientLight = settings.ambient;
        else if (settings.emptyScene)
            RenderSettings.ambientLight = Color.white;

        plane.renderer.material = m;
    }

    private function DestroyScene ()
    {
        GameObject.DestroyImmediate (camera);
        GameObject.DestroyImmediate (plane);
        GameObject.DestroyImmediate (previewTexture);
    }

    function UpdateMaterialPreview (m : Material) : RenderTexture
    {
        if (!m)
            return;

        var saveAmbientLight = RenderSettings.ambientLight;
        var saveMainTexture = m.mainTexture;
        if (settings.bakeMainTexAsWhite)
            m.mainTexture = null;

        // setup
        if (!camera)
            SetupScene ();
        camera.SetActiveRecursively(true);
        UpdateScene (m);

        var res = FindLargestTextureResolution (plane.renderer.sharedMaterial, settings.minTextureResolution, settings.maxTextureResolution);
        var rt = RenderCameraToRenderTexture (camera.camera, res.x, res.y);

        // restore
        camera.SetActiveRecursively(false);
        RenderSettings.ambientLight = saveAmbientLight;
        m.mainTexture = saveMainTexture;

        previewTexture = rt;
        return rt;
    }

    function CaptureMaterial(m : Material)
    {
        var matAssetPath = AssetDatabase.GetAssetPath (m);
        var assetPath = System.IO.Path.Combine (System.IO.Path.GetDirectoryName (matAssetPath), System.IO.Path.GetFileNameWithoutExtension (matAssetPath));

        var rt = UpdateMaterialPreview (m);
        RenderTextureToPNG (rt, settings.bakeAlpha, assetPath + ".png");
    }

    function OnEnable ()
    {
        if (!settings)
            settings = new BakeMaterialSettings ();
        SetupScene ();
        visible = true;
    }

    function OnDisable ()
    {
        DestroyScene ();
        settings.Save ();
        visible = false;
    }

    static function GetTargetMaterial () : Material
    {
        return EditorUtility.InstanceIDToObject (Selection.activeInstanceID) as Material;
    }

    function OnSelectionChange ()
    {
        Repaint ();
    }

    function Update ()
    {
        var rebuildScene = false;
        if (scheduleBakeOnNextUpdate)
        {
            Bake ();
            scheduleBakeOnNextUpdate = false;
            rebuildScene = true;
        }

        if (originalScene == "" && EditorApplication.currentScene == "")
            settings.emptyScene = true;

        if (settings.emptyScene && originalScene == "" && EditorApplication.currentScene != "")
        {
            DestroyScene ();
            if (EditorApplication.SaveCurrentSceneIfUserWantsTo ())
            {
                originalScene = EditorApplication.currentScene;
                EditorApplication.NewScene ();
            }
            else
                settings.emptyScene = false;
            rebuildScene = true;
        }
        else if (!settings.emptyScene && originalScene != "")
        {
            EditorApplication.OpenScene (originalScene);
            rebuildScene = true;
            originalScene = "";
        }

        if (rebuildScene)
        {
            SetupScene ();
        }

        if (rebuildScene || stateChanged || !settings.emptyScene)
        {
            UpdateMaterialPreview (lastMaterial);
            Repaint ();
            stateChanged = false;
        }
    }

    function OnGUI ()
    {
        var material = GetTargetMaterial ();
        if (lastMaterial != material)
            UpdateMaterialPreview (material);
        if (material)
            lastMaterial = material;

        EditorGUILayout.BeginHorizontal();
            EditorGUILayout.BeginVertical(GUILayout.MaxWidth(200));
                if (!(originalScene == "" && EditorApplication.currentScene == ""))
                {
                    settings.emptyScene = !EditorGUILayout.BeginToggleGroup("Scene ligthing", !settings.emptyScene);
                    EditorGUILayout.EndToggleGroup();
                }
                settings.useCustomLights = EditorGUILayout.BeginToggleGroup("Custom lighting", settings.useCustomLights);
                if (settings.useCustomLights)
                {
                    EditorGUI.indentLevel = 1;
                    settings.ambient = EditorGUILayout.ColorField("Ambient", settings.ambient);
                    for (var q = 0; q < settings.kLights; ++q)
                    {
                        settings.enableLight[q] = EditorGUILayout.BeginToggleGroup("Light", settings.enableLight[q]);
                        EditorGUI.indentLevel = 2;
                            settings.colorLight[q] = EditorGUILayout.ColorField("Color", settings.colorLight[q]);
                            settings.dirLight[q] = EditorGUILayout.Vector2Field("Direction", settings.dirLight[q]);
                        EditorGUILayout.EndToggleGroup();
                    }
                }
                EditorGUI.indentLevel = 0;
                EditorGUILayout.EndToggleGroup();

                settings.bakeAlpha = EditorGUILayout.Toggle("Bake Alpha", settings.bakeAlpha);
                settings.bakeMainTexAsWhite = !EditorGUILayout.Toggle("MainTex", !settings.bakeMainTexAsWhite);
                settings.minTextureResolution = EditorGUILayout.IntField("Min Resolution", settings.minTextureResolution);
                settings.maxTextureResolution = EditorGUILayout.IntField("Max Resolution", settings.maxTextureResolution);
                settings.minTextureResolution = Mathf.Max(2, settings.minTextureResolution);
                settings.maxTextureResolution = Mathf.Max(settings.minTextureResolution, settings.maxTextureResolution);

                EditorGUILayout.BeginHorizontal();
                if (GUILayout.Button("Bake"))
                {
                    CaptureMaterial (lastMaterial);
                }
                if (GUILayout.Button("Bake Selected"))
                {
                    scheduleBakeOnNextUpdate = true;
                }
                EditorGUILayout.EndHorizontal();

            EditorGUILayout.EndVertical();

            texViewScrollPosition = EditorGUILayout.BeginScrollView (texViewScrollPosition);
                var r = GUILayoutUtility.GetAspectRect(1.0f);
                if (previewTexture)
                    EditorGUI.DrawPreviewTexture(r, previewTexture);
            EditorGUILayout.EndScrollView();
        EditorGUILayout.EndHorizontal();

        if (GUI.changed)
        {
            stateChanged = true;
        }
    }

    @MenuItem("Custom/Bake Material ...", false, 5)
    static function CreateBakeEditor()
    {
        var window = EditorWindow.GetWindow(BakeMaterial);
        window.title = "Bake Material";
        window.minSize = kWindowMinSize;
        window.Show();
    }

    @MenuItem("Custom/Bake Selected Materials", false, 4)
    static function Bake()
    {
        var instanceIDs = Selection.instanceIDs;
        var currentScene = EditorApplication.currentScene;

        var wasAlreadyVisible = BakeMaterial.visible;
        var window = EditorWindow.GetWindow(BakeMaterial);

        if (window.settings.emptyScene)
        {
            if (!EditorApplication.SaveCurrentSceneIfUserWantsTo ())
                return;
            EditorApplication.NewScene ();
        }

        window.SetupScene ();
        for (var i in instanceIDs)
        {
            var m : Material = EditorUtility.InstanceIDToObject (i) as Material;
            if (m)
                window.CaptureMaterial (m);
        }
        window.DestroyScene ();

        if (window.settings.emptyScene && currentScene)
        {
            EditorApplication.OpenScene (currentScene);
        }

        if (!wasAlreadyVisible)
            window.Close ();
    }

    static function FindLargestTextureResolution (m : Material, minTexRes : int, maxTexRes : int) : Vector2
    {
        var res = Vector2 (minTexRes, minTexRes);
        for (var n in BakeMaterialSettings.kStandardTexNames)
        {
            if (!m.HasProperty (n))
                continue;

            var t : Texture = m.GetTexture (n);
            if (!t)
                continue;

            res.x = Mathf.Max (res.x, t.width);
            res.y = Mathf.Max (res.y, t.height);
        }
        res.x = Mathf.Min (res.x, maxTexRes);
        res.y = Mathf.Min (res.y, maxTexRes);
        return res;
    }

    static function RenderCameraToRenderTexture (cam : Camera, width : int, height : int) : RenderTexture
    {
        var rt = cam.camera.targetTexture;
        if (rt && rt.width != width && rt.height != height)
            DestroyImmediate(rt);
        if (!rt)
            rt = new RenderTexture (width, height, 24);
        cam.camera.targetTexture = rt;
        cam.camera.Render ();
        return rt;
    }

    static function RenderTextureToPNG (rt : RenderTexture, bakeAlpha : boolean, assetPath : String)
    {
        RenderTexture.active = rt;

        var screenShot = new Texture2D (rt.width, rt.height, bakeAlpha? TextureFormat.ARGB32 : TextureFormat.RGB24, false);
        screenShot.ReadPixels (Rect (0, 0, rt.width, rt.height), 0, 0); 

        RenderTexture.active = null;

        var bytes = screenShot.EncodeToPNG ();
        System.IO.File.WriteAllBytes (assetPath, bytes);

        AssetDatabase.ImportAsset (assetPath, ImportAssetOptions.ForceUpdate);
    }
}