[android-developers] Re: HTC and LG haven't implemented Android in the right way

AFAIK it is possible to specify point size array along with vertex
array. Enabling point sprites turns points to textured quads. Turn on
bilinear filtering and alpha test or blending. Of course the texture
should depict a star.

On 29 сен, 23:26, Kostya Vasilyev <kmans...@gmail.com> wrote:
> 29.09.2011 23:01, MobileVisuals ?????:
>
> > I claim that HTC HD doesn't support OpenGL ES 2.0, because size
> > attenuation is a part of OpenGL ES 1.1 and it is not supported.
>
> Quite possibly, you're right...
>
> > So HTC hasn't implemented the things that they say in the
> > specification, but why not?
>
> Who knows?
>
> You could contact their support, but even if they provide a plausible
> answer (and that's a big "if"), it's not going to magically fix all the
> HTC devices out there...
>
> > Thanks for the idea, do you mean like this?
>
> > Scale to small size if the sprite is far away.
> > Scale to medium size if the sprite is medium distance.
> > Scale to big size if the sprite is close.
>
> More or less - you are currently doing continuous range scaling of your
> sprites (I presume). If you replace them with texture mapped quads, you
> could always use the same image, or pick one of the ones predefined at
> various scale factors, to improve the image quality and performance.
> Sort of like mip-mapping.
>
> But that's not the core idea - the main thing is to replace attenuated
> points with texture mapped quads.
>
> > That could work for other animations, but it would be very slow for my
> > star cluster animations. There are hundreds of stars in each cluster.
> > As it is now, I draw each star cluster in one single glDrawArrays
> > call. That makes it fast.
>
> Hundreds doesn't sound too bad - at those poly counts, it's the fill
> rate (overdraw) that can kill performance. But since sprites are
> typically small, it probably won't be an issue.
>
> > Wouldn't I have to make one glDrawArrays call for each one of the
> > stars if I had to scale them in different sizes? That would mean
> > hundreds of glDrawArrays calls instead of one.
>
> Not the way I'm reading the docs (mind you, my GL is more than a little
> rusty - last time I worked with 3D was more than 10 years ago)....
>
> But it seems like you should be able to draw all quads that use the same
> texture in one call, using GL_TRIANGLES or GL_QUADS (not _STRIP or _FAN,
> because those are always joined). This can product transparency
> artifacts depending on their z-order, so you'd need to sort the quads
> according to their texture and z-order both.
>
> Or just forgo the mipmapping for initial tests, then there's be one less
> thing to worry about with respect to sorting.
>
> > A point sprite is a screen-aligned element of variable size that is
> > defined by a single point. Would it really be a sprite if it was
> > mapped to a quad polygon?
>
> If it looks like a sprite, and quacks like a sprite...
>
> --
> Kostya Vasilyev

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