Re: [fxtf-drafts] [compositing] Question: How to properly blend and composite isolated groups (#440)

Thanks for that explanation. It looks like I misread what separable blend modes was (I though it meant the blend mode was applied separately per composite layer, not per color component of RGB).

So it seems that the mix-blend-mode is only applied when the groups are blended together? I tried to follow that through with adding a color D to the example and tried to then see if that would work:

```html
<div id="A" style="background-color: rgba(255, 255, 255, 1.0);">
  <div id="B" style="background-color: rgba(0, 128, 0, 0.25);">
    <div id="C" style="background-color: rgba(255, 0, 0, 0.5); mix-blend-mode: difference;">
      <div id="D" style="background-color: rgba(0, 0, 255, 0.25);">Test Element</div>
    </div>
  </div>
</div>
```

```
Root Group
  - #A
  - #B
  - isolated group
    - #C 
    - #D
```

```
rootGroup = normal(normal(root backdrop, A), B)
isolatedGroup = normal(C, D)
difference(rootGroup, isolatedGroup)
```

That almost worked but wasn't quite the right color. I tried `difference` with the isolateGroup as well but that didn't seem to work either.

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Received on Monday, 1 November 2021 16:59:23 UTC