This function asks you to define a rectangle within the room, and then it marks all mp_grid cells "touch" that rectangle as being forbidden, meaning that the path-finding functions cannot cross them. The image below illustrates how this works:
As you can see, the rectangle defined by (50, 90) to (200, 180) marks all the equivalent mp_grid cells that it touches as being forbidden.
mp_grid_add_rectangle(id, x1, y1, x2, y2);
|id||Index of the mp_grid that is to be used|
|x1||The x coordinate of the left side of the rectangle to check.|
|y1||The y coordinate of the top side of the rectangle to check.|
|x2||The x coordinate of the right side of the rectangle to check.|
|y2||The x coordinate of the bottom side of the rectangle to check.|
mp_grid_add_rectangle(grid, 0, 0, 100,
The above code will mark as forbidden all cells of the mp_grid indexed in the variable "grid" that fall within the area 0,0 to 100,200.