[fxtf-drafts] [compositing-2] Example 2 in section 3.4 for mix-blend-mode is misleading (#549)

Overruler has just created a new issue for https://github.com/w3c/fxtf-drafts:

== [compositing-2] Example 2 in section 3.4 for mix-blend-mode is misleading ==
[Section 3.4 mix-blend-mode](https://drafts.fxtf.org/compositing/#mix-blend-mode) Example 2 uses screen blending mode with colors that give the impression of additive blending. However, the 3 colors "red", "lime" and "blue" are only a singular special case for which additive and screen blending produce the same result; this is not the case in general.

To avoid giving this false impression, rather than "red", "lime" and "blue", the three colors could be changed to "fuchsia", "green" and "green":

```
<svg style="background-color: black;">
  <style>circle { mix-blend-mode: screen; }</style>
  <circle cx="40" cy="40" r="40" fill="fuchsia"></circle>
  <circle cx="80" cy="40" r="40" fill="green"></circle>
  <circle cx="60" cy="80" r="40" fill="green"></circle>
</svg>
```

Under additive blending these colors would also sum to produce white, but under screen blending mode they don't:
![Screenshot (58)](https://github.com/w3c/fxtf-drafts/assets/3786941/413660dc-f543-4c39-b9a6-91e6b99e9777)


Please view or discuss this issue at https://github.com/w3c/fxtf-drafts/issues/549 using your GitHub account


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Received on Friday, 9 February 2024 17:49:34 UTC