The Issue

In the relatively short amount of time that I've spent creating in PICO-8 and viewing other PICO-8 developers' creations, I've realized that jittery diagonal movement seems to be one of the most common issues in PICO-8 projects. Through online searches, I've seen a few different methods of preventing this problem, but so far I haven't seen anything that also accounts for accelerating/decelerating velocity. The cart and code below showcases the solution (heavily inspired by the code from two of @Krystman's Lazy Devs videos: https://www.youtube.com/watch?v=oBjZ1W50brM and https://www.youtube.com/watch?v=stoDWgR-kF8) that I'm currently using in a WIP game. I'm wondering what other solutions users have found, and would greatly appreciate feedback on how my current method can be improved.

Notes: the code below is not the same code I am using in my WIP game, so recommendations on how to save tokens or make my code cleaner may not be applicable. Additionally, I am not actually following @Krystman's tutorial series, I only used the aforementioned videos for ideas on this specific issue, so if the code was improved on later in the series, I have not seen it.

Cart

smoothdiagonalmovement

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smoothdiagonalmovement

by tuballion

Cart #smoothdiagonalmovement-0 | 2024-09-01 | Code ▽ | Embed ▽ | License: CC4-BY-NC-SA

Code

function _init()
	x=60
	y=60
	xv=0
	yv=0
	speed=2
	accel=0.3
	olddir=0
	destutter=false
	toggle="normal"

	function smooth(x1,x2,x3)
		return (x1-x2)*x3
	end
end

function _update()
	if btnp(🅾️) then
		if toggle=="normal" then
			toggle="smooth"
			pal(8,12,1)
		else
			toggle="normal"
			pal(8,8,1)
		end
	end

	local input=btn()&0xf
	local inputarr={1,2,0,3,5,6,3,4,8,7,4,0,1,2,0}
	local dir=inputarr[input] or 0
	local dxarr={-1,1,0,0,-0.71,0.71,0.71,-0.71}
	local dyarr={0,0,-1,1,-0.71,-0.71,0.71,0.71}
	local dx=dxarr[dir] or 0
	local dy=dyarr[dir] or 0

	xv+=smooth(dx*speed,xv,accel)
	yv+=smooth(dy*speed,yv,accel)

	if dir>=5 and toggle=="smooth" then
		local xspeed=abs(xv)
		local yspeed=abs(yv)

		if dir!=olddir or toggle!=oldtoggle then
			destutter=false
		elseif abs(xspeed-yspeed)<0.1 and not destutter then
			x=flr(x+0.5)
			y=flr(y+0.5)

			local newspeed=(xspeed+yspeed)/2

			xv=dx*newspeed
			yv=dy*newspeed

			destutter=true
		end
	end

	oldtoggle=toggle

	olddir=dir

	x+=xv
	y+=yv
end

function _draw()
	cls()
	spr(1,x,y)
	print(toggle,1,1,8)
end