If you have only fully transparent / fully opaque parts in your texture (like in your example), you should use depthwrite in combination with an alphafunc. Look at textures/karith/e8bgrate01b for example. The alphafunc GE128 will discard all pixels with an alpha value < 127, and depthwrite will write the remaining pixels to the depth buffer, so anything further away is masked out.
If you need true alpha blending, the renderer would have to sort the surfaces back-to-front for correct rendering, but the renderer sorts only by shader type (skybox, opaque surface, transparent surface, particle, etc.).