Polygon Mesh need help

i have a problem with polygon mesh…i have a square and i draw a polygon…for example a “T”
at this point i should have all my square black and in the “T” area i should see what there’s under the black square polygon…
anybody can help me pls??

Could you be more precise in the description of your problem?

i have a texture in the background covered with a black square… when i draw a polygon i fill a matrix with “1” to know the area of my polygon…now i should delete this area and see the texture where in my matrix there a “1” and black where there’s “0”…and i don’t know how to do this…pls help