Re: [css4-images] custom blending effects

Hi Rik,

On 27/11/2011, at 3:42 PM, Rik Cabanier wrote:

> What if we extend the SVG compositing spec to include CSS and provide the ability to do a custom blend using glsl? It seems pretty straightforward to come up with a syntax since the notation is basic.
> If we combine this with transitions, it seems that this would be powerful and also enable your use case.

I have no attachment to the syntax or approach I suggested, so sure. I'd like to see your proposal.

I just wanted to float the idea since I'd seen a lot of interest for cross-fade on The Twitters, and figured we could provide even more useful transitions (blends/whatever-you-want-to-call-them).

Dean

> 
> We do need to come up with a way to calculate background in a HTML context both for compositing and filters...
> 
> Rik
> 
> 
> On Thu, Nov 24, 2011 at 3:13 PM, Dean Jackson <dino@apple.com> wrote:
> This is a completely half-baked proposal, but I figured it was ok to embarrass myself on this list rather than forget about the idea. This is definitely not a proposal from Apple as a whole. Just one fool mumbling in public.
> 
> The cross-fade() function is going to be extremely useful. However, cross-fading is one of many blending operations [*]. IIRC SMPTE (and the larger SMIL spec) list a set of predefined functions like wipe, iris, dissolve, etc.
> 
> [*] The terminology is going to be confusing. Typically such operations are called 'transitions' but that term already has a meaning in CSS. Obviously 'blending' here isn't the same operation as you typically associate with compositing and Photoshop-like effects. We're just talking about moving from one image to another image over time.
> 
> I wonder if we should add another operation to CSS 4 images that allows more blending operations. My suggestion would be to allow a CSS Shader with three hard-coded inputs (like cross-fade): image1, image2 and amount of blend (0 - 1). This would allow for some pretty snazzy effects.
> 
> cross-fade would just be the special/common case of e.g. image-blend(crossfade, image1, image2, 0.4)
> 
> [1] Here's the SMIL set of predefined transitions: http://www.w3.org/TR/2005/REC-SMIL2-20050107/smil-transitions.html
> 
> Dean
> 
> 
>