[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Public WebGL] Weird alpha issue.
> But the problem isn't alpha issues with images. It is issues with alpha
> in compositing with the HTML page which would probably also happen with
> vertex colors having alpha < 1.0.
I agree - this has nothing to do with alpha issues in textures or 2D
canvasses. It's all to do with destination-alpha rendering contexts and
fragment shaders that write alpha<1.0...for whatever reason...not
necessarily from texture.
There are actually multiple problems that this test is currently
1) When you ask for a rendering context WITHOUT destination alpha - do you
actually get what you're asking for? (Not currently in Minefield - and the
last time I could test it, not in Chrome when it's using ANGLE under
Windows. Chrome does seem to get this right for OpenGL rendering
2) Does the compositor correctly composite destination-alpha rendering
contexts into the HTML page? (Currently, Minefield and Chrome disagree on
how this is done for partially transparent pixels - I don't know which of
them is correct - I suspect that whether a destination-alpha buffer
constitutes a pre-multiplied-alpha canvas is the bone of contention here).
3) When you write an alpha==0.0 pixel from your shader, will the pixel be
unconditionally culled (as both Chrome and Minefield do right now) - or
will the pixel's Z value be written to the depth buffer and a zero written
into the destination alpha plane (as the OpenGL ES 2.0 spec implies -
since it doesn't support glAlphaFunc)?
You are currently subscribed to email@example.com.
To unsubscribe, send an email to firstname.lastname@example.org with
the following command in the body of your email: