Sprite's containsPoint method check alpha

[liajoy]

Hello!

`Sprite` support `containsPoint` method, But it just check the point is in the sprite area depend on width and height not by imageData.

For example, if the sprite image is a totally transparent image, `containsPoint` should always return false.

My thought maybe like this

1. extract `imageData` from `app.stage`

2. check the pixel relative to the point is alpha

Any better advise to do this?

Thank you!

[ivan.popelyshev]

Here, two threads for you: 

https://github.com/pixijs/pixi.js/issues/5311

SUMMARY:

there are several ways, but nothing is packaged in pixi, because their authors weren't ready to publish it. You have to do it and be a hero who makes a plugin.

[liajoy]

thanks!

[liajoy]

hello again! I've saw those 'guide'. Thanks so much.
I just want to know if some point is contained of some sprite. Seems there's no need to concern about shader?
Another question is `extract.pixels()` will return something wrong if the displayObject shifted and out of the box. Seems it didn't count the `transform` of displayObject?

const circle = new PIXI.Graphics();

circle.x = 200;

circle.beginFill(0xabcdef);
circle.drawCircle(0, 0, 100);
circle.endFill();

const pixels = app.renderer.extract.pixels(circle); // [0, ...0]

So in some situation, `extract.pixels()` doesn't work perfectly, use 2d canvas is the only way to get the correct pixels?

 

[ivan.popelyshev]

> Another question is `extract.pixels()` will return something wrong if the displayObject shifted and out of the box

Known bug, its too difficult to fix because all my possible fixes were very big, difficult , and thy were rejected. Try use your own code based on `extract`: manually call `renderer.render` and `readPixels` instead.

As for graphics, why do you need extract it? Its already have perfect containsPoint() method.

For graphics containsPoint() exists, for sprites you can analyze original textures and make a packed bitmap out of them, no need to use `extract` at all.