【Unity渲染】Camera RenderToCubemap 渲染到立方體紋理

Unity聖典 傳送門：http://www.ceeger.com/Script/Camera/Camera.RenderToCubemap.html

Camera.RenderToCubemap 有4個重載

（1）bool  RenderToCubemap(Cubemap cubemap)

　　  bool  RenderToCubemap(Cubemap cubemap,int faceMask)

　　可以用於在編輯器中生成場景靜態立方體貼圖。faceMask是一個bitfield比特數，表示那個立方貼圖面應該被渲染，每個位對

應於一個面。比特數是Cubemapface枚舉的整型值。默認的所有六個立方貼圖面都被渲染（默認值63的低6位是打開的）。

// Render scene from a given point into a static cube map.
//從給定的點渲染場景到以靜態立方貼圖
// Place this script in Editor folder of your project.
//放置這個腳本到工程的Editor文件夾中
// Then use the cubemap with one of Reflective shaders!
//然后用一個Reflective shaders 來使用這個立方貼圖
class RenderCubemapWizard extends ScriptableWizard {
    var renderFromPosition : Transform;
    var cubemap : Cubemap;

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

    function OnWizardCreate () {
        // create temporary camera for rendering
        //為渲染創建臨時相機
        var go = new GameObject( "CubemapCamera", Camera );
        // place it on the object
        //放置它到物體上
        go.transform.position = renderFromPosition.position;
        go.transform.rotation = Quaternion.identity;

        // render into cubemap
        //渲染到立方貼圖    
        go.camera.RenderToCubemap( cubemap );

        // destroy temporary camera
        //銷毀臨時相機
        DestroyImmediate( go );
    }

    @MenuItem("GameObject/Render into Cubemap")
    static function RenderCubemap () {
        ScriptableWizard.DisplayWizard.<RenderCubemapWizard>(
        "Render cubemap", "Render!");
    }
}

（2）bool  RenderToCubemap(RenderTexture cubemap)

         bool  RenderToCubemap(RenderTexture cubemap,int faceMask)

        這個用於實時反射到立方貼圖渲染紋理。這是非常耗時的，尤其是所有六個立方貼圖面在每一幀中都被渲染。

如果渲染失敗這個函數將返回false，某些顯卡不支持這個函數。

　　同時,一定要將 RenderTexture.isCubemap = true

using UnityEngine;
using System.Collections;
using UnityEngine.UI;
using UnityEditor;

// Attach this script to an object that uses a Reflective shader.
// Realtime reflective cubemaps!
//附加這個腳本到使用了Reflective shader的物體上 
//實時反射立方貼圖
[ExecuteInEditMode]
public class RealtimeCubemap :MonoBehaviour
{
    int cubemapSize = 128;
    //一幀渲染一面
    bool oneFacePerFrame = false; 
    Camera cam = null;
    RenderTexture cubemap = null;
    Material mat = null;

    void Start()
    {
        //在啟動時渲染所有六個面
        UpdateCubemap(63);
    }

    void LateUpdate()
    {
        if (oneFacePerFrame)
        {
            int faceToRender = Time.frameCount % 6;
            int faceMask = 1 << faceToRender;
            UpdateCubemap(faceMask);
        }
        else
        {
            //所有六個面
            UpdateCubemap(63);
        }
    }

    
void UpdateCubemap (int faceMask )
{
    if (cam == null)
    {
        GameObject go = new GameObject("CubemapCamera", typeof(Camera));

        //隱藏在場景中
        go.hideFlags = HideFlags.HideAndDontSave;
        go.transform.position = transform.position;
        go.transform.rotation = Quaternion.identity;
        cam = go.GetComponent<Camera>();

        ///不要渲染較遠的部分
        cam.farClipPlane = 100;
        cam.enabled = false;
    }
    if (mat == null)
    {
        mat = new Material(Shader.Find("Custom/RealtimeCubemap"));
        mat.hideFlags = HideFlags.HideAndDontSave;
        GetComponent<Renderer>().material = mat;
    }

    if (cubemap == null)
    {
        cubemap = new RenderTexture(cubemapSize, cubemapSize, 16);
        cubemap.isPowerOfTwo = true;
        cubemap.isCubemap = true;
        cubemap.hideFlags = HideFlags.HideAndDontSave;
        mat.SetTexture("_Cubemap", cubemap);
    }

    cam.transform.position = transform.position;
    cam.RenderToCubemap(cubemap, faceMask);
}

    void OnDisable()
    {
        DestroyImmediate(cam);
        DestroyImmediate(cubemap);
    }

}