Re: Utility of background-composite and background-blend-mode?

On Fri, Feb 1, 2013 at 10:52 AM, Rik Cabanier <cabanier@gmail.com> wrote:

> On Thu, Jan 31, 2013 at 1:41 PM, Robert O'Callahan <robert@ocallahan.org>wrote:
>
>> What is the difference between background-blend-mode:<MODE> and
>> mix-blend-mode: background <MODE>?
>>
>
> 'background-blend-mode' specifies how the background images blend with
> each other. Conceptually, the background blend and composite with each
> other and the resulting bitmap is then used as the element's background.
> 'mix-blend-mode: background <MODE>' allows you to specify the blend mode
> on that background image.
>

Was this answer correct? It looks to me like "background-composite"
specifies "how the background images blend with each other".

In fact, I am completely confused. background-blend-mode says "Each
background image will blend with the element's background and the
background images at a lower z-index." So if there's just one background
image, which of mix-blend-mode:background <mode>" and
"background-blend-mode" controls how that image blends with the element's
background (which I assume means "backdrop"?)?

A description of the processing model --- a pseudo-algorithm for drawing
--- would be really helpful.

Rob
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