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Re: [Public WebGL] Weird alpha issue.



Oh - and the actual version information is:

Build identifier: Mozilla/5.0 (Windows NT 6.1; rv:2.0b8pre) Gecko/20101030
Firefox/4.0b8pre


> 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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