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Re: [Public WebGL] Weird alpha issue.



I've been running with the validator turned on - turning it off didn't
make a bit of difference.  FWIW: I'm getting the same results on the
Minefield/Linux 64bit version.  I get no errors/warnings/messages in the
Error console and no GL errors in either Minefield or Chrome (although I
may not be checking absolutely everywhere).

I've tried three chrome builds under Win7/32bit:

    9.0.567.0              -- Canary, fresh install - 10 minutes ago.
    8.0.553.25            -- Dev channel.
    7.0.501.0(56955) -- I forget where this came from.

...always the same result, light smoke under Chrome, dark under Minefield.

Is it possible that some "default" setting in the WebKit stuff is set
differently by Chrome & Minefield?  Maybe other tests have been
overriding that default - and I'm not?

Unless there are other suggestions, I'll start reducing it down to the
simplest case I can and put up an example page.  That might take a day
or two though - I have some other commitments to handle first.

  -- Steve


On 10/30/2010 04:54 PM, Benoit Jacob wrote:
> I'm a bit clueless here; since you're getting this in current nightlies, we do share the same code with WebKit for WebGL texture format conversions, so that can't be the explanation.
>
> Does it make any difference when you go to about:config and toggle the preference webgl.shader_validator?
>
> Benoit
>
> ----- Original Message -----
>   
>> I have Minefield set up to auto-update and it actually updated just as
>> I
>> started typing this email - so I guess I have the latest! ...and the
>> color is still much darker than in Chrome.
>>
>> I took a pair of side-by-side screenshots with the latest versions of
>> both browsers:
>>
>> http://www.sjbaker.org/tmp/smoke_differences.png
>>
>> (It's kinda hard to see the smoke on the Minefield side - but it's
>> much
>> more obvious in motion).
>>
>> If it helps, the texture map is in:
>>
>> http://www.sjbaker.org/tmp/Smoke.png
>>
>> -- Steve
>>
>>
>>
>> On 10/30/2010 11:08 AM, Benoit Jacob wrote:
>>     
>>> What's your Minefield build? Two weeks ago, I landed important
>>> texture fixes that could be related to that. Please try with the
>>> latest nightly:
>>>
>>> http://nightly.mozilla.org/
>>>
>>> Benoit
>>>
>>> ----- Original Message -----
>>>
>>>       
>>>> I'm running some particle system tests - using an RGBA .png image
>>>> with
>>>> fuzzy mid-grey translucent smoke puffs. There are lots of particles
>>>> layered on top of each other.
>>>>
>>>> What's odd is that the smoke puff is much lighter in color on
>>>> Chrome
>>>> than it is on Minefield - even with both browsers running
>>>> side-by-side
>>>> on the exact same Win7/32bit/nVidia machine displaying the exact
>>>> same
>>>> scene. Everything else in the scene looks utterly identical in the
>>>> two
>>>> windows.
>>>>
>>>> I'm kinda suspecting some funky thing going on with pre-multiplied
>>>> alpha. Is someone messing with my texture?
>>>>
>>>> DETAILS:
>>>>
>>>> The setup for drawing is:
>>>>
>>>> gl.enable ( gl.DEPTH_TEST ) ;
>>>> gl.depthMask ( false ) ;
>>>> gl.enable ( gl.BLEND ) ;
>>>> gl.blendFunc ( gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA ) ;
>>>>
>>>> ...with everything else left at default values.
>>>>
>>>> The frag shader says:
>>>>
>>>> float4 color = texture2D ( fire, UV ).rgba * (1.0-smokeAmount) +
>>>> texture2D ( smoke, UV ).rgba * smokeAmount ;
>>>> color.a *= timeVaryingAlpha ;
>>>> gl_FragColor = color ;
>>>> }
>>>>
>>>> ...and in this case, smokeAmount is 1.0 (so we should see only the
>>>> smoke
>>>> map...and that works) and timeVaryingAlpha varies between 0.0 and
>>>> 1.0
>>>> as
>>>> you'd expect.
>>>>
>>>> My image 'onload' function says:
>>>>
>>>> gl.bindTexture ( gl.TEXTURE_2D, texture ) ;
>>>> gl.pixelStorei ( gl.UNPACK_FLIP_Y_WEBGL, true);
>>>> gl.texImage2D ( gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA,
>>>> gl.UNSIGNED_BYTE, image ) ;
>>>> gl.generateMipmap ( gl.TEXTURE_2D ) ;
>>>> gl.bindTexture ( gl.TEXTURE_2D, null ) ;
>>>>
>>>> Help!
>>>>
>>>> -- Steve
>>>>
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