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Attention | Topic was automatically imported from the old Question2Answer platform. |
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Asked By | Boohooligan |
Hi,
I’m trying to create a basic enemy AI that has two states: IDLE and WANDER.
I’m using Navmesh 3D demo from Godot’s asset store.
If stop_distance is set to 1.0, the AI will pathfind to a single location, then once (target_position - transform.origin).length() evaluates to value of about 5.7 the AI stops pathfinding never reaching the IDLE state again (tested with print() statements).
Setting the stop_distance to above 5.7 correctly switches between IDLE and WANDER states and AI proceeds to pathfind.
Any idea why this might be happening?
extends KinematicBody
var move_speed = 3.0
enum STATE {IDLE, WANDER}
var state = STATE.IDLE
onready var start_position = get_global_transform().origin
onready var target_position = get_global_transform().origin
var nav = null
var path = []
var stop_distance = 1.0
func _ready():
nav = get_parent() # Navigation node is parent of enemy node in the scene tree during run-time
func _process(delta):
match state:
STATE.IDLE:
var next_waypoint = Vector3(rand_range(5, 20), translation.y, rand_range(5, 20))
target_position = start_position + next_waypoint
var p = nav.get_simple_path(start_position, target_position, true)
if not p.empty():
path = Array(p)
path.invert()
state = STATE.WANDER
STATE.WANDER:
var to_walk = delta * move_speed
var to_watch = Vector3.UP
while to_walk > 0 and path.size() >= 2:
var pfrom = path[path.size() - 1]
var pto = path[path.size() - 2]
to_watch = (pto - pfrom).normalized()
var d = pfrom.distance_to(pto)
if d <= to_walk:
path.remove(path.size() - 1)
to_walk -= d
else:
path[path.size() - 1] = pfrom.linear_interpolate(pto, to_walk / d)
to_walk = 0
var atpos = path[path.size() - 1]
var atdir = to_watch
atdir.y = 0
var t = Transform()
t.origin = atpos
t = t.looking_at(atpos + atdir, Vector3.UP)
set_transform(t)
if path.size() < 2:
path = []
set_process(false)
if (target_position - transform.origin).length() < stop_distance:
start_position = get_global_transform().origin
state = STATE.IDLE
Optional: Why divide to_walk by d for the rate argument in pfrom.linear_interpolate(pto, to_walk / d)?
Answer: this ensures the enemy AI lerps to destination at constant speed until the end, otherwise it will begin to slow down as it approaches the destination.
Optional 2: Why does the Navmesh3D demo project inverts the path array(after converting it to Array)? Unfortunately it’s not documented or explained in their code.
Answer: removing last element from array is more efficient rather than from the beginning.