Heres the Grid object:
Room Size: 3456x3456
NEW ROOM EVENT
///New Grid when any room starts
cell_width = 64; //Cell Width of grid
cell_height = 64; //Cell Height of grid
hcells = room_width/cell_width; //Number of horizontalcells
vcells = room_height/cell_height; //Number of verticalcells
global.grid = mp_grid_create(0,0,hcells,vcells,cell_width,cell_height); //Create the Grid
mp_grid_add_instances(global.grid, obj_solid, false) //Add instances to grid
DRAW EVENT:
draw_set_alpha(0.1);
mp_grid_draw(global.grid)
for (var i=0; i< room_width ; i+=64)
{
draw_line(i,0,i,room_height);
}
for (i = 0; i< room_height;i+=64)
draw_line(0,i,room_width,i);
draw_set_alpha(1);