Pathfinding and roaming states

[Monster25]

I've been using pathfinding for a while now in my game (top down shooter). The enemies are supposed to have 2 different states whenever they are not engaged, idle and roam. While in idle they stay still and while they are roaming they pick a random direction and move there until an alarm makes them pick again between idle and roam just to make them act a bit more natural. I've succesfuly implemented the pathfinding using motion planning for when the enemies chase you or when they are startled and look for you in your last position but for some reason when I try to use the same code but calculate the end coordinates for the roaming path they won't budge at all.
This is the code found in their roaming state:

scr_enemy_movement();
//Pathfinding
var cx = (lengthdir_x(1,enemy_angle)/32)*32+16;
var cy = (lengthdir_y(1,enemy_angle)/32)*32+16;
if (mp_grid_path(global.grid,path,x,y,cx,cy,1))
{
path_start(path, movespeed,path_action_stop, false);
}

the enemy movement script calculates their movespeed and for some reason if I try and use lengthdir_x and lengthdir_y to calculate the end of their path they won't move at all but if I place the player's coordinates or any other hard coordinate instead, they will move accordingly and correctly.

I'm not sure what's happening and why this is not working, is the pathfinding not able to use lengthdir calculations?

 

[The-any-Key]

Are you sure get a path?

 

[Monster25]

Yes they do receive a path, while in any other state they do, if it involves hard coordinates they do but if I calculate them with lengthdir_x they suddenly don't

 

[Monster25]

I don't understand why it works with the volatile coordinates of the player which keep changing but it won't work with the lengthdirs since they get their coordinates the same volatile way.

 

[Monster25]

bump

 

[Monster25]

I've tried creating a separate object like a flag where the enemy is supposed to move and use its coordinates instead but it still won't work, it also clutters the game a lot.

 

[anomalous]

Always output your expected values if you run into an issue. It will usually give you some clues as to what's going on.

scr_enemy_movement();
//Pathfinding
var cx = (lengthdir_x(1,enemy_angle)/32)*32+16;
var cy = (lengthdir_y(1,enemy_angle)/32)*32+16;
show_debug_message("cx = " + string(cx);
show_debug_message("cy = " + string(cy);
if (mp_grid_path(global.grid,path,x,y,cx,cy,1))
{
show_debug_message("path found");
path_start(path, movespeed,path_action_stop, false);
}

 

[Monster25]

Allright I did as you suggested, the cx and cy are being calculated correctly but the path won't start at all.

 

[Monster25]

I've tracked the problem down to the statement
if (mp_grid_path(global.grid,path,x,y,cx,cy,1))
the result of this is always 0. If I switch cx and cy with the player's x and y it suddenly works, the same happens for any constant coordinates.

 

[anomalous]

I still think your cx/cy are incorrect.
var cy = (lengthdir_y(1,enemy_angle)/32)*32+16;

That's your destination y? lengthdir 1 will be between -1 and 1? Thats what, the upper right of your room?
Then /32*32..that's not snapping to grid, you truncate for that like div 32 *32. +16 is moving to the center of the tile, that's the only thing that looks correct to me.

Normally I expect to see an origination x/y ADDED to the lengthdirx/y values.
so var cx = (x) + lengthdir_x...

In any case, if that's not it, I suggest you draw a circle at x/y and cx/cy, and use draw mp grid (the debug where it shows you the grids green/red collision), and you will see the issue.

 

[Monster25]

Oh it seems you are right, the lengthdirs are missing the origination x/y but how can I make them become negative if they need to be? I've added them both but the enemy seems to move to the south east only like he's adding x and y.

 

[Monster25]

this is the updated code
var cx = x+(lengthdir_x(1,enemy_angle)/32)*32+16;
var cy = y+(lengthdir_y(1,enemy_angle)/32)*32+16;
show_debug_message("cx = " + string(cx));
show_debug_message("cy = " + string(cy));
if (mp_grid_path(global.grid,roam,x,y,cx,cy,1))
{
show_debug_message("path found");
path_start(roam, movespeed,path_action_stop, false);
}
else
show_debug_message("path not found");

I've drawn the circles as well and it seems he always goes to the south east.

 

[Jesse Jaramillo]

If you would like, i have essentially perfected my version of pathfinding(chasing the player) and roaming AI for my enemy objects in a game i have been working on.
Link to my post is here: https://forum.yoyogames.com/index.php?threads/dungeon-dwellers-very-early-build.25453/
if you want me to explain how i went about creating this effect let me know and ill try to break it down as best as possible.