unity 相机fade脚本示例

//Class to fade from camera 0 to 1, and back from 1 to 0
//This class assumes there are only two scene cameras
//---------------------------------------
using UnityEngine;
using System.Collections;
//---------------------------------------
public class CameraFader : MonoBehaviour
{
    //---------------------------------------
    //Reference to cameras (all cameras in the scene to be composited)
    public Camera[] Cameras;

    //Reference to camera color (color to multiply with render)
    public Color[] CamCols = null;

    //Fade in/out time in seconds (total time for a fade in one direction)
    public float FadeTime = 2.0f;

    //Final material to apply to render (Can be used to apply a shader to final rendered pixels)
    public Material Mat = null;
    //---------------------------------------
    // Use this for initialization
    void Start () 
    {
        //Assign render textures to each camera
        foreach(Camera C in Cameras)
            C.targetTexture = new RenderTexture(Screen.width, Screen.height, 24); //Create texture
    }
    //---------------------------------------
    //This function is called once per frame after the camera has 
    //finished rendering but before the render is shown
    //It has a companion function OnPreRender (which is called before rendering)
    void OnPostRender()
    {
        //Define screen rect
        Rect ScreenRct = new Rect(0,0,Screen.width,Screen.height);

        //Source Rect
        Rect SourceRect = new Rect(0,1,1,-1);

        //Render each camera to their target texture
        for(int i = 0; i<Cameras.Length; i++)
        {
            //Render camera
            Cameras[i].Render();

            //Draw camera textures to screen using this camera
            GL.PushMatrix();
            GL.LoadPixelMatrix(); //Get pixel space matrix
            Graphics.DrawTexture(ScreenRct, Cameras[i].targetTexture, SourceRect, 0,0,0,0, CamCols[i]); //Draws each camera as layer
            GL.PopMatrix(); //Reset matrix
        }
    }
    //---------------------------------------
    //This function is called afer OnPostRender
    //And when final pixels are to be shown on screen
    //src = current render from camera
    //dst = texture to be shown on screen
    void OnRenderImage(RenderTexture src, RenderTexture dst)
    {
        //Frame finished rendering, now push final pixels to screen with Mat applied (can apply custom shader here)
        Graphics.Blit(src, dst, Mat);
    }
    //---------------------------------------
    //Function to lerp between color From to Color To over period TotalTime
    //This function is used to fade alpha for topmost rendered camera CamCols[1]
    public IEnumerator Fade(Color From, Color To, float TotalTime)
    {
        float ElapsedTime = 0f;

        //Loop while total time is not met
        while(ElapsedTime <= TotalTime)
        {
            //Update color
            CamCols[1] = Color.Lerp(From, To, ElapsedTime/TotalTime);

            //Wait until next frame
            yield return null;

            //Update Time
            ElapsedTime += Time.deltaTime;
        }

        //Apply final color
        CamCols[1] = Color.Lerp(From, To, 1f);
    }
    //---------------------------------------
    //Sample update function for testing camera functionality
    //Press space bar to fade in and out between cameras
    void Update()
    {
        //Fade camera in or out when space is pressed
        if(Input.GetKeyDown(KeyCode.Space))
        {
            StopAllCoroutines();

            //Should we fade out or in
            if(CamCols[1].a <= 0f)
                StartCoroutine(Fade(CamCols[1], new Color(0.5f,0.5f,0.5f,1f), FadeTime)); //Fade in
            else
                StartCoroutine(Fade(CamCols[1], new Color(0.5f,0.5f,0.5f,0f), FadeTime)); //Fade out
        }
    }
    //---------------------------------------
}