# How to solve the dual camera, dual scene post rendering use EffectComposer

**URL:** <https://discourse.threejs.org/t/how-to-solve-the-dual-camera-dual-scene-post-rendering-use-effectcomposer/15813>\
**Category:** Questions\
**Tags:** webgl-renderer\
**Created:** [June 2, 2020, 6:23am UTC](https://discourse.threejs.org/t/how-to-solve-the-dual-camera-dual-scene-post-rendering-use-effectcomposer/15813 "2020-06-02T06:23:10Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![treasureMoment](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.threejs.org/treasuremoment/32/2552_2.png) [@treasureMoment](https://discourse.threejs.org/u/treasureMoment)\
**Post date:** [June 2, 2020, 6:23am UTC](https://discourse.threejs.org/t/how-to-solve-the-dual-camera-dual-scene-post-rendering-use-effectcomposer/15813/1 "2020-06-02T06:23:11Z")

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in my case:

> let camera = new PerspectiveCamera( fieldOfView, aspectRatio, nearPlane, farPlane );  
> let cameraOrtho = new OrthographicCamera( -width / 2, width / 2, height / 2, -height / 2, 1, 10 );
> 
> let scene = new Scene();  
> let sceneOrtho = new Scene()

Both scene and camera will be rendered to rendeder at the same time.  
Now I want to add post rendering to the first scene，But when I did this, the second scene in the scene disappeared。  
like this:

> ```
> if(this.composer) {
> this.composer.update();
> this.composer.render(delta);
> }else{
> this.renderer.render( this.scene, this.camera );
>             
> } 
> this.renderer.render( this.sceneOrtho, this.cameraOrtho );
> 
> ```

what should I do？  
Thanks

---

<div class="post-metadata">

**Author:** ![Mugen87](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.threejs.org/mugen87/32/5645_2.png) [@Mugen87](https://discourse.threejs.org/u/Mugen87)\
**Post date:** [June 2, 2020, 8:58am UTC](https://discourse.threejs.org/t/how-to-solve-the-dual-camera-dual-scene-post-rendering-use-effectcomposer/15813/2 "2020-06-02T08:58:36Z")

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Since you are performing multiple renderings for a single frame, you have to set `renderer.autoClear` to `false`. At the beginning of your `render()` function, call `renderer.clear()` manually. This approach is used in the official examples multiple times, e.g. in [webgl\_camera](https://threejs.org/examples/webgl_camera).