Dang! It sure is weird whatever it is. I wondered if it is something to do with alpha doing something odd. All I do is load an RGB PNG image and copy the red channel into the alpha channel. It has been working fine before when I uploaded only the alpha channel as a GL_ALPHA texture, but now I upload and use the whole RGBA I get these dumb lines on the screen. Blend mode is GL_ONE,GL_ONE.
[Edit] It seems that GL_ONE,GL_ONE produces the white lines, whereas GL_SRC_ALPHA,GL_ONE does not, even if the entire source alpha is 1.0.
[Edit] It seems that GL_ONE,GL_ONE produces the white lines, whereas GL_SRC_ALPHA,GL_ONE does not, even if the entire source alpha is 1.0.