How do I stop a camera from rendering to a RenderTexture?

Question

I have a camera in my scene that has a Target Texture set as a Render Texture. I want that camera to render the scene into the Render Texture, but then stop rendering anymore, essentially freezing the frame into the Render Texture. How can I achieve this? Disabling the camera or setting its target texture to null seems to just make the Render Texture appear invisible.

derHugo derHugo · Accepted Answer · 2020-09-17T07:04:50

If you want to have like a snapshot function you could do it like this

public class SnapshotController : MonoBehaviour
{
    [Tooltip("If you want to capture a specific camera drag it here, otherwise the MainCamera will be used")]
    [SerializeField] private Camera _camera;
 
    [Tooltip("If you have a specific RenderTexture for the snapshot drag it here, otherwise one will be generated on runtime")]   
    [SerializeField] private RenderTexture _renderTexture;
    
    private void Awake()
    {
        if(!_camera) _camera = Camera.main;
    
        if(!_renderTexture)
        {
            _renderTexture = new RenderTexture(Screen.width, Screen.height , 24 , RenderTextureFormat.ARGB32);
            _renderTexture.useMipMap = false;
            _renderTexture.antiAliasing =1;
        }
    }
    
    public void Snapshot(Action<Texture2D> onSnapshotDone)
    {
        StartCoroutine(SnapshotRoutine(onSnapshotDone));
    }
    
    private IEnumerator SnapshotRoutine (Action<Texture2D> onSnapshotDone)
    {
        // this also captures gui, remove if you don't wanna capture gui
        yield return new WaitForEndOfFrame(); 
               
        // If RenderTexture.active is set any rendering goes into this RenderTexture
        // instead of the GameView
        RenderTexture.active = _renderTexture;
        _camera.targetTexture = _renderTexture;
               
        // renders into the renderTexture
        _camera.Render();
     
        // Create a new Texture2D        
        var result = new Texture2D(Screen.width,Screen.height,TextureFormat.ARGB32,false);
        // copies the pixels into the Texture2D          
        result.ReadPixels(new Rect(0,0,Screen.width,Screen.height),0,0,false);
        result.Apply();
       
        // reset the RenderTexture.active so nothing else is rendered into our RenderTexture      
        RenderTexture.active = null;
        _camera.targetTexture = null;
    
        // Invoke the callback with the resulting snapshot Texture
        onSnapshotDone?.Invoke(result);
    }
}

You would then use it like e.g.

// Pass in a callback telling the routine what to do when the snapshot is ready
xy.GetComponent<SnapshotController>(). Snapshot(HandleNewSnapshotTexture);

...

private void HandleNewSnapshotTexture (Texture2D texture)
{
    var material = GetComponent<Renderer>().material;

    // IMPORTANT! Textures are not automatically GC collected. 
    // So in order to not allocate more and more memory consider actively destroying
    // a texture as soon as you don't need it anymore
    if(material.mainTexture) Destroy (material.mainTexture);     

    material.mainTexture = texture;
}

How do I stop a camera from rendering to a RenderTexture?

2 Answers