Clear Rect in Render Texture

[Hebbe]

Hi!

I'm using pixi 4.5.3 and can't find a way to clear out an rectangle from my transparent render texture. Seems that all blend modes have gl.ONE_MINUS_SRC_ALPHA in them 

Is there any hack around this?

I have a large renderTexture with mostly static bitmap text and I want to update only parts that have changed for better performance. Is there any other way to update only part of an rendertexture while retaining transparency?

Thanks!

 

[ivan.popelyshev]

There's a branch for that case, make your own blendMode: https://github.com/pixijs/pixi.js/pull/4049 , the build is here: https://pixijs.download/dev-blendmodes-class/pixi.js

var gl = app.renderer.gl; //the context
var mySuperBlendMode = new PIXI.BlendMode(gl.ONE, gl.ONE); //its actually kinda ADD ;)

sprite.blendMode = mySuperBlendMode;

Unfortunately its too heavy change for pixi-v4 , so it will be introduced in v5. For now you can just use the branch, its up-to-date

UPD. Do remember that both canvas and texture are premultiplied by default, that means (R*a, G*a, B*a, a) are stored instead (R,G,B,a). All coefficients are applied to those numbers.

[dmko]

I forgot to followup on your erase mode update... thanks for doing that btw! Is this the same answer? (will be native in v5 only)

[ivan.popelyshev]

Yes, answer is the same, but now there are a number of people who use that feature. And I updated the branch before I answered this one post.