[opensource-dev] Review Request: VWR-24420: PNG images which specify "background color" lose alpha layer when imported.

[Dave Booth]

Thats a pretty good bit of thinking out loud there, Ponzu....

Personally I'd say thats a "clean" fix for this. However it all depends 
on how things are stored server-side - if the asset server code 
automatically assumes that every texture has an alpha channel and 
supplies a "solid" one for those where the upload doesnt provide one, 
any benefit of specifying at upload time is moot.

On 1/10/2011 10:34, Ponzu wrote:
> A common cause of z-buffer problems in SL is textures that do not 
> *need* an alpha channel that contain one anyway.  Lots of content in 
> SL is created by rank amateurs (me for example).
>
> What if the upload dialog had a check box?
>
>     [ ] This texture should have an alpha channel.
>
> If the box is not checked, the alpha channel is removed.  If it is 
> checked, it is retained, unless it is not there, in which case the 
> user gets an error message.
>
> Just thinking out loud.
>
> ponzu
>
> On Sun, Jan 9, 2011 at 9:59 AM, Thickbrick Sleaford 
> <thickbrick.sleaford at gmail.com <mailto:thickbrick.sleaford at gmail.com>> 
> wrote:
>
>     This is an automatically generated e-mail. To reply, visit:
>     http://codereview.secondlife.com/r/74/
>
>
>     Review request for Viewer.
>     By Thickbrick Sleaford.
>
>
>       Description
>
>     Current code composites RGBA PNG images that contain a bKGD chunk down to RGB, discarding the alpha channel. This patch removes that code, since it contradicts purpose of the bKGD chunk as described in the PNG spec and as commonly used.
>
>
>       Testing
>
>     Tested uploading the 2 images attached to VWR-24420 with and without the patch. Before patch, "bad alpha.png" was uploaded as RGB, after patch, both images were uploaded as RGBA.
>
>     *Bugs: * VWR-24420 <http://jira.secondlife.com/browse/VWR-24420>
>
>
>       Diffs
>
>         * doc/contributions.txt (UNKNOWN)
>         * indra/llimage/llpngwrapper.h (UNKNOWN)
>         * indra/llimage/llpngwrapper.cpp (UNKNOWN)
>
>     View Diff <http://codereview.secondlife.com/r/74/diff/>
>
>
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