modify ease of dripping over already painted areas

[bigjcr]

Hi, I noticed ease of dripping is different when painting over clean areas and already painted areas (color flows further over paint). Yet I haven't been able to find the factor which makes it different, how can I modify inkpainter so that ease of dripping is the same no matter where I paint?

What I want to do is to make color spread to be the same as ink dripping, I have been playing around with HeightDrip.shader, PaintHeight.shader and InkPainterFoundation.cginc, but I haven't been able to get such results, every factor in shiftZ seems to end up affecting both dripping and color spread, I haven't found which one affects only color spread.

Thanks.