No, I actually haven't been able to. It threw me for a loop
because I was expecting non-premultiplied because that's what the PNG
spec says. What do you want to do with non-premultiplied that you are
having trouble doing with premultiplied?
-Anton
On May 29, 4:40 am, djp <[email protected]> wrote:
> I was wandering if you managed to load a RGBA texture without pre-
> multiplied alpha.
>
> I'm working with an assumption that every texture is alpha pre-
> multiplied, because I was unable to load a RGBA texture without pre-
> multiplication (on G1). I'd love to know if it's possible or not.
>
> Thanks,
> David
>
> On May 28, 9:56 pm, Anton <[email protected]> wrote:
>
> > The ball.png that you reference above is 30x30 pixels. As MrChaz
> > said, you must use power of two sized bitmaps. Otherwise the
> > texImage2D function will not accept your texture. It seems likely
> > that that is what is going on here. Also, this works in the 16 bits
> > per pixel modes as well. You don't need a separate alpha channel in
> > your frame buffer to do alpha compositing, so a simple RGB454 frame
> > buffer works, which is what you get if you use a SimpleEGLConfigChooser
> > (false) to select your pixel format. 16bpp formats are twice as fast
> > when it comes to rendering as 32bpp formats (if your fill rate
> > limited, and if you're rendering a 2D game with sprites then you
> > probably are).
>
> > Another word of caution, PNG files are supposed to (if you follow
> > the spec) have non-premultiplied alpha channels. But it seems that
> > not many people actually follow the standard, and so you can find PNG
> > files that do it either way. If your PNG files are in fact using non-
> > premultiplied alpha then the glBlendFunction should be
> > (GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA). If they use
> > premultiplied alpha then it should be as MrChaz said (GL10.GL_ONE,
> > GL10.GL_ONE_MINUS_SRC_ALPHA). If you use the first and see dark halos
> > around all of your sprites then you probably have premultiplied alpha
> > PNGs.
>
> > As a side note, premultiplied alpha is better for a number of
> > reasons. It simplifies a number of compositing operations and treats
> > all of the color and alpha channels in a uniform way. It also allows
> > for super-luminous pixels.
>
> > -Anton
>
> > On May 27, 7:00 pm, Nate <[email protected]> wrote:
>
> > > I am rendering this PNG with no transparency just
> > > fine:http://n4te.com/temp/test.png
> > > However if I try to render this PNG (with transparency) with the exact
> > > same code, I just get a white box:http://n4te.com/temp/ball.png
>
> > > I am loading the PNG into a texture like this:
> > > Bitmap bitmap = BitmapFactory.decodeStream(input);
> > > int[] temp = new int[1];
> > > gl.glGenTextures(1, temp, 0);
> > > textureID = temp[0];
> > > gl.glBindTexture(GL10.GL_TEXTURE_2D, textureID);
> > > gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER,
> > > GL10.GL_NEAREST);
> > > gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER,
> > > GL10.GL_NEAREST); // GL_LINEAR for quality.
> > > gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S,
> > > GL10.GL_CLAMP_TO_EDGE);
> > > gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T,
> > > GL10.GL_CLAMP_TO_EDGE);
> > > GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);
> > > bitmap.recycle();
>
> > > I am using this blending:
> > > gl.glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA);
>
> > > How is it possible to render a PNG with transparency in OpenGL ES?
>
> > > Thanks!
> > > -Nate
>
>
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google
Groups "Android Developers" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/android-developers?hl=en
-~----------~----~----~----~------~----~------~--~---
