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Re: [Public WebGL] Weird alpha issue.



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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