Unity3D中制作CubeMap的工具

介绍将场景渲染到Cubemap，并且导出成PNG贴图的工具。

将场景渲染到CubeMap

• 首先搭建一个创景，然后创建一个cubemap，并且把camera放在合适的位置
• 把以下代码复制到一个C#文件里，并且放到根目录下的Editor文件夹里。
• 然后从顶部菜单里选择GameObject/Render into Cubemap
• 在弹出面板里填入渲染坐标（Camera坐标）和目标cubemap，点击“Render”按钮，完成！

创建Cubemap的方式有2种

• Legacy Cubemap：直接创建就行，注意设置里Readable打勾

• 先导入任意一张贴图，设置成Cubemap，参考下图的设置。

渲染到Cubemap代码：

using UnityEngine;
using UnityEditor;
using System.Collections;

public class RenderCubemapWizard : ScriptableWizard {
    public Transform renderFromPosition;
    public Cubemap cubemap;

    void OnWizardUpdate() {
        string helpString = "Select transform to render from and cubemap to render into";
        bool isValid = (renderFromPosition != null) && (cubemap != null);
    }

    void OnWizardCreate() {
        // create temporary camera for rendering
        GameObject go = new GameObject("CubemapCamera");
        go.AddComponent<Camera>();

        // place it on the object
        go.transform.position = renderFromPosition.position;
        go.transform.rotation = Quaternion.identity;

        // render into cubemap
        go.GetComponent<Camera>().RenderToCubemap(cubemap);

        // destroy temporary camera
        DestroyImmediate(go);
    }

    [MenuItem("GameObject/Render Into Cubemap")]
    static void RenderCubemap () {
        ScriptableWizard.DisplayWizard <RenderCubemapWizard> (“Render Into  Cubemap", "Render!");
    }
}

从Cubemap导出6张贴图

有时候做法是先搭建一个白模场景渲染到cubemap贴图，让原画细化贴图，再贴回到cubemap里。

• 把以下代码复制到一个C#文件里，并且放到根目录下的Editor文件夹里。
• 然后从顶部菜单里选择GameObject/Save CubeMap To Png
• 在弹出面板里填入cubemap，点击“Save”按钮，完成！导出目录是Assets根目录。
• 注意导出的6张贴图尺寸刚好是cubemap原来尺寸的1/4.

Cubemap导出6张贴图的代码：

using UnityEngine;
using UnityEditor;
using System.Collections;

public class SaveCubemapToPngWizard : ScriptableWizard {
    public Cubemap cubemap;

    void OnWizardUpdate () {
        helpString = "Select cubemap to save to individual png";
        isValid = (cubemap != null);
    }

    void OnWizardCreate() {
        int width = cubemap.width;
        int height = cubemap.height;

        Debug.Log(Application.dataPath + "/" +cubemap.name +"_PositiveX.png");
        var tex = new Texture2D (width, height, TextureFormat.RGB24, false);
        // Read screen contents into the texture        
        tex.SetPixels(cubemap.GetPixels(CubemapFace.PositiveX));        
        // Encode texture into PNG
        var bytes = tex.EncodeToPNG();      
        System.IO.File.WriteAllBytes(Application.dataPath + "/"  + cubemap.name +"_PositiveX.png", bytes);       

        tex.SetPixels(cubemap.GetPixels(CubemapFace.NegativeX));
        bytes = tex.EncodeToPNG();     
        System.IO.File.WriteAllBytes(Application.dataPath + "/"  + cubemap.name +"_NegativeX.png", bytes);       

        tex.SetPixels(cubemap.GetPixels(CubemapFace.PositiveY));
        bytes = tex.EncodeToPNG();     
        System.IO.File.WriteAllBytes(Application.dataPath + "/"  + cubemap.name +"_PositiveY.png", bytes);       

        tex.SetPixels(cubemap.GetPixels(CubemapFace.NegativeY));
        bytes = tex.EncodeToPNG();     
        System.IO.File.WriteAllBytes(Application.dataPath + "/"  + cubemap.name +"_NegativeY.png", bytes);       

        tex.SetPixels(cubemap.GetPixels(CubemapFace.PositiveZ));
        bytes = tex.EncodeToPNG();     
        System.IO.File.WriteAllBytes(Application.dataPath + "/"  + cubemap.name +"_PositiveZ.png", bytes);       

        tex.SetPixels(cubemap.GetPixels(CubemapFace.NegativeZ));
        bytes = tex.EncodeToPNG();     
        System.IO.File.WriteAllBytes(Application.dataPath + "/"  + cubemap.name +"_NegativeZ.png", bytes);       


        DestroyImmediate(tex);
    }

    [MenuItem("GameObject/Save CubeMap To Png")]
    static void SaveCubeMapToPng () {
        ScriptableWizard.DisplayWizard <SaveCubemapToPngWizard> (“Save CubeMap To Png", "Save");
    }
}