Why does this crash

[flamingairplane]

Godot Version

4.2.2

I was trying to increase the players movement smoothly and I got to this but after running it crashed.

#Movemet Modes
if Input.is_action_pressed("Sprint"):
	while current_speed < sprinting_speed:
		current_speed + 0.1
else:
	while current_speed > walikng_speed:
		current_speed - 0.1

[choirmaestro]

In my experience, the while function is not very forgiving. If the game is just freezing upon you pressing sprint, it’s probably that. Try switching each ‘while’ with an ‘if’ instead. (not tested)

[tayacan]

You made an infinite while loop. The reason it’s infinite is that you never actually update the value of current_speed. If you do:

#Movemet Modes
if Input.is_action_pressed("Sprint"):
	while current_speed < sprinting_speed:
		current_speed = current_speed + 0.1
else:
	while current_speed > walikng_speed:
		current_speed = current_speed - 0.1

Then it will actually update the value, and thus the while loop will eventually end, and your game won’t crash. However, it won’t do what you want (changing speed smoothly), because this whole while loop will be run in a single frame!

Basically, all the code you write in the _process and _physics_process will be run repeatedly, every frame. For this reason, it’s pretty rare that you want to use a while-loop in either of these functions (but it does happen).

In order to update the speed smoothly, you’ll want to just update it once per frame:

#Movemet Modes
if Input.is_action_pressed("Sprint"):
	if current_speed < sprinting_speed:
		current_speed = current_speed + 0.1
else:
	if current_speed > walikng_speed:
		current_speed = current_speed - 0.1

This still isn’t a very good way to do it, though, for several reasons:

• How fast the speed changes will depend on the framerate
• It’s possible to overshoot the target speed, so you can end up, for example, at a speed slightly faster than the sprint speed, or slightly slower than walking speed

To fix the first problem, choose a higher value than 0.1, but then multiply it by delta. To fix the second problem, use the move_toward function, which will never go past its target value. That way, you can also drop the if-statements checking if the speed is too low or high.

#Movemet Modes
if Input.is_action_pressed("Sprint"):
	current_speed = move_toward(current_speed, sprinting_speed, 5 * delta)
else:
	current_speed = move_toward(current_speed, walking_speed, 5 * delta)

[flamingairplane]

Thank you so much, but a question I had about your solution. What exactly does delta do in this context?

[tayacan]

delta is the time between the last two frames. By multiplying with it, you ensure that the acceleration is independent of the framerate.

Imagine, for example, that sometimes a frame takes one second, and sometimes it takes two seconds (obviously, in reality frames are much faster, but 1 and 2 are easy numbers to think about). We want to accelerate - for example - 5 m/s, so we ask for the speed to change with 5 * delta. If a frame takes one second to run, that means we increase the speed by 5, but if a frame takes two seconds to run, we instead increase the speed by 10. And in the more likely scenario where a frame takes, say, 1/60th of a second, we increase the speed by 5/60, which is roughly 0.08333.