[compositing] Add plus-darker blend mode

• From: Dean Jackson <dino@apple.com>
• Date: Mon, 19 Jan 2015 16:31:04 -0800
• To: FX <public-fx@w3.org>
• Message-Id: <CC6F69E4-E704-4FA2-84B4-2D736D095D30@apple.com>

Our designers at Apple often request a blending operation that is not supported in the CSS Compositing and Blending specification: plus-darker. You can find many examples and discussion of this mode if you Bing on the Google.

We’d like to add this mode to Level 2.

Details are here: http://en.wikipedia.org/wiki/Blend_modes#Addition

The math is pretty simple:

R = min(0, (1 - D) + (1 - S))

(We should maybe consider adding plus-lighter as well, and subtractive modes based on designer feedback)

Dean

Received on Tuesday, 20 January 2015 00:31:35 UTC