Question: How do you implement pathfinding in GameMaker?


GameMaker Studio provides robust tools for creating pathfinding behaviors in games. To implement pathfinding, GameMaker uses functions associated with the mp_grid system, which is part of the Motion Planning functions.

Here's how to implement pathfinding:

Step 1: Create a Grid for Pathfinding

Firstly, create an mp_grid that corresponds to the room where your object will be using pathfinding:

var cell_size = 32; // Define the size of each grid cell global.myGrid = mp_grid_create(0, 0, room_width/cell_size, room_height/cell_size, cell_size, cell_size);

Step 2: Add Obstacles to the Grid

Identify solid objects or obstacles and add them to the grid so that the pathfinding algorithm can avoid them:

mp_grid_add_instances(global.myGrid, obj_wall, false); // Replace 'obj_wall' with your obstacle instance

Step 3: Create a Path

When you want your object to move from one point to another, you create a path for it:

var path_index = path_add(); // Creates a new path and stores the index if(mp_grid_path(global.myGrid, path_index, x, y, target_x, target_y, false)) { path_start(path_index, speed, path_action_stop, true); // Start following the path } else { // Path could not be created, handle this situation }

In this code, target_x and target_y represent the coordinates of the destination. The path_start function then moves the instance along the created path at a given speed.

Step 4: Destroying Paths and Grids When Done

Remember to clean up your paths and grids when they are no longer needed to free up memory:

path_delete(path_index); mp_grid_destroy(global.myGrid);

You can call these in the appropriate event, such as the object's destruction event or the room end event.

Additional Notes

  • Adjust the cell_size depending on the precision you need and the performance cost you're willing to accept.
  • You can also use mp_grid_cell_is_empty to check if a cell in the grid is empty (no collision detected) before adding an instance there.
  • If your game features dynamic obstacles, you'll need to regularly update the grid using mp_grid_clear_all and re-add instances to the grid.

This outline provides a basic idea of how to implement pathfinding in GameMaker Studio. For complex games, you may need to delve deeper into the documentation and tailor the pathfinding to fit your specific needs.

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