Alpha overlay in line drawing in cocos2d-iphone

Hi all,

Im a beginner in cocos2d.
Im working on a line drawing app in which I draw lines of various colors. I’ve modified and implemented it from a source and the problem Im facing is color blending. On the line edges, in order to do anti aliasing, fade out color is applied on them. When I draw another line over it, the lines look not that much good i.e the overlay of the blending is visible as fading out color as in the image in
.

I tried using {GL_ONE, GL_ONE_MINUS_SRC_ALPHA} and {GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA} as the blend functions and also tried some others, but couldn’t get the correct blending. I can’t solve this for the last three days.
Can some one help me to sort this out??