Blending Problem

I'm having a little trouble with blending in my Asteroids game. The asteroids are png files with transparency, this way when they overlap you don't see the black box around the asteroids because it's transparent.

Here's how I'm using blending.

Code:

glEnable( GL_BLEND );
    glBlendFunc(GL_SRC_ALPHA, GL_ONE);

Here's what I'm talking about
http://i14.photobucket.com/albums/a3...ions-Aster.png

So basically I want the pixels around the asteroid to be transparent, but the actual asteroid pixels to not show through.

In Direct3D you do this:

1. Create color map.
2. Create alpha map (White = opaque, black = transparent)
3. Create dds file that merges alpha channel with color channels
4. Set blend mode to: SRC_BLEND - SRC_ALPHA, DEST_BLEND - INV_SRC_ALPHA
5. Render

Perhaps you can 'port' that to GL.

Sample: