//should work something like this code taken from gridtest//

/*
int scl = 20;
int cols, rows;

int grid[][];

void setup() {
  size(400,400);  
  background(0);
  
  cols = width / scl;
  rows = height/ scl;
  
  grid = new int[cols][rows];
  
}


void draw() {
  
  background(0);
  
  if (mousePressed) {
    int curcol = mouseX / scl;
    int currow = mouseY / scl;
    grid[curcol][currow] = 1;
    //line( mouseX,mouseY,pmouseX,pmouseY);
  }
  
  for (int i = 0; i < cols; i++) {
    for (int j = 0; j < rows; j++) {
      int val = grid[i][j];
      if (val == 1) rect(i*scl,j*scl,scl,scl);   
    }
  }
  
  
}*/