# When I set a RenderTexture instance as the mask of another RenderTexture, failed

**URL:** <https://phaser.discourse.group/t/when-i-set-a-rendertexture-instance-as-the-mask-of-another-rendertexture-failed/1693>\
**Category:** Phaser 3\
**Created:** [March 15, 2019, 7:40am UTC](https://phaser.discourse.group/t/when-i-set-a-rendertexture-instance-as-the-mask-of-another-rendertexture-failed/1693 "2019-03-15T07:40:28Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![foukenma](https://yyz2.discourse-cdn.com/free1/user_avatar/phaser.discourse.group/foukenma/32/700_2.png) [@foukenma](https://phaser.discourse.group/u/foukenma)\
**Post date:** [March 15, 2019, 7:40am UTC](https://phaser.discourse.group/t/when-i-set-a-rendertexture-instance-as-the-mask-of-another-rendertexture-failed/1693/1 "2019-03-15T07:40:29Z")

</div>

I create a renderTexture, and drawFrame something on this renderTexture, then I make another renderTexture, and want to set this renderTexture to be the mask of the former, but the console output

```javascript
Uncaught TypeError: Cannot read property 'loadIdentity' of undefined
    at GraphicsWebGLRenderer [as renderWebGL] (phaser.js:143312)

```

```javascript
// code like 
let A = this.add.renderTexture( x, y, width, height );
A.drawFrame( key, frame );
let B = this.make.renderTexture( { x, y, width, height } );
A.setMask( B.createBitmapMask() )

```