mp_grid_create(left,top,hcells,vcells,cellwidth,cellheight) This function creates the grid. It returns an index that must be used in all other calls. You can create and maintain multiple grid structures at the same moment. left and top indicate the position of the top-left corner of the grid. hcells and vcells indicate the number of horizontal and vertical cells. Finally cellwidth and cellheight indicate the size of the cells.

mp_grid_add_instances(id,obj,prec) Marks all cells that intersect an instance of the indicated object as being forbidden. You can also use an individual instance by making obj the id of the instance. Also you can use the keyword all to indicate all instances of all objects. prec indicates whether precise collision checking must be used (will only work if precise checking is enabled for the sprite used by the instance).

mp_grid_path(id,path,xstart,ystart,xgoal,ygoal,allowdiag) Computes a path through the grid. path must indicate an existing path that will be replaced by the computer path. xstart and ystart indicate the start of the path and xgoal and ygoal the goal. allowdiag indicates whether diagonal moves are allowed instead of just horizontal or vertical. The function returns whether it succeeded in finding a path. (Note that the path is independent of the current instance; It is a path through the g rid, not a path for a specific instance.)