On Mon, Sep 19, 2016 at 3:48 PM, Amelia Bellamy-Royds < amelia.bellamy.royds@gmail.com> wrote: > Changing how opacity works is not an option. It is a group property, not > an inherited one. It takes the rendered and composited group, and adjusts > alpha. For its original purpose in 2D SVG, this is essential. You can > create an image from many different shapes, one for each color, and have it > fade in and out as a whole, without revealing the underlying layering. > > Would it be possible to instead add a different property (say, "alpha"), > which *is* inheritable, not group, and adjusts the alpha of every paint > operation by that factor? It would be similar to applying opacity to leaf > nodes, but you could set it once on the group and have it inherit. It would > also have to apply to each background, text, etc., separately, so that > container elements with a mix of child content plus their own > background/text wouldn't end up compounding the transparency of their > children. > That doesn't sound very useful because it means that each painting operation will alpha blend/interact with what came before. I can't think of a scenario where you'd want that. Can you provide an example? > For any child element that you *wanted* to treat as a flattened layer, > you would set alpha=1 and opacity=*alpha-factor* (possibly using CSS > variables to keep track of what your alpha factor is). > > Those of you who know more than me about how compositing is implemented, > does this sound feasible? > > Otherwise, my best recommendation to people who want the 3D opacity effect > is to use CSS variables to set your alpha factor on your group, and then > use opacity:var(--alpha) on any (flat) layer that actually includes painted > content. > > Unfortunately, however, for now that means not being able to use CSS > animations/transitions or web animation to transition alpha. We're still > waiting for typed CSS custom properties that can be interpolated. > > ~ABR >
Received on Monday, 19 September 2016 14:58:45 UTC