RE: [css3] support for filters

I agree that the performance of blending in a non GPU accelerated world will be low, especially if you apply animation. The drawing model of most browsers is probably also not designed to read back underlying pixels.
With a GPU, you can use a pixel shader to get the blending effect which should perform very well. I'm unsure how video and plug-ins would work. Maybe there will be a rule that they are not allowed to have blending applied to them or that they will ignore it.

Having filters as a first pass is more feasible. Browsers already need to know the element's bitmap to do transitions and animations so they should be able to apply a filter to it.

Rik

From: Simon Fraser [mailto:smfr@me.com]
Sent: Thursday, January 06, 2011 3:56 PM
To: Rik Cabanier
Cc: Paul Irish; Cameron McCormack; Charles Pritchard; ed@opera.com; www-style@w3.org; Dan Clark
Subject: Re: [css3] support for filters

On Jan 6, 2011, at 3:48 PM, Rik Cabanier wrote:


It looks like people want Adobe PDF/Flash style blending in addition to filters.  :)
It would be great if we could even add blending to the HTML imaging model. PDF style blending is probably overkill but Flash style should be sufficient.
(ps filters and blending are very different concepts. I think it will be a lot harder to implement blending than filters)

Adobe has ample documentation and knowledge about this so we can certainly help out here.

Applying blend modes that require reading the destination pixels imposes severe constraints on the rendering model used by the browsers, and I think we should, initially at least, stay away from graphical operations that require reading the destination pixels.

The rendering pipeline used by modern browsers is now much more complex than simply drawing into a bitmap. They may use islands of OpenGL content, and other OS-supplied, GPU-based rendering frameworks to present parts of the content like video and plug-ins. Supporting blending in such an environment, while maintaining acceptable rendering performance may not be possible.

Simon