ZBrushCentral

Brush setup - not tuching the surrounding geometry

Well im not sure how i can explain this. Is there a way to set the brush to just look at the white areas in the Alpha texture?
It feel like the brushes i have now will deform the surface around it.I want the original geometry intact like if i use projection master if you know what i mean?

like the brush compined with the drag stroke if i remember the name corectly

I want to create a brush to create cracks in a surface. i want to do this freehand an i dont want the dragstroke but withou the surrounding (near where i paint) to rise or lower.

Is it poosible?