RenderTexture.active

Description

Currently active render texture.

All rendering goes into the active RenderTexture. If the active RenderTexture is null everything is rendered in the main window.

Setting RenderTexture.active is the same as calling Graphics.SetRenderTarget. Typically you change or query the active render texture when implementing custom graphics effects; if all you need is to make a Camera render into a texture then use Camera.targetTexture instead.

When a RenderTexture becomes active its hardware rendering context is automatically created if it hasn't been created already.

Additional resources: Graphics.SetRenderTarget.

using UnityEngine;
using System.Collections;

// Get the contents of a RenderTexture into a Texture2D
public class ExampleClass : MonoBehaviour
{
    static public Texture2D GetRTPixels(RenderTexture rt)
    {
        // Remember currently active render texture
        RenderTexture currentActiveRT = RenderTexture.active;

        // Set the supplied RenderTexture as the active one
        RenderTexture.active = rt;

        // Create a new Texture2D and read the RenderTexture image into it
        Texture2D tex = new Texture2D(rt.width, rt.height);
        tex.ReadPixels(new Rect(0, 0, tex.width, tex.height), 0, 0);
        tex.Apply();

        // Restore previously active render texture
        RenderTexture.active = currentActiveRT;
        return tex;
    }
}