lulz with Aspectus\Terminal

composer.json

{
	"minimum-stability": "dev",
	"prefer-stable": true,
	"config": {
		"preferred-install": {
			"netherphp/*": "source",
			"*": "dist"
		},
		"allow-plugins": {
			"dealerdirect/phpcodesniffer-composer-installer": true,
			"netherphp/composer-plugin": true
		}
	},
	"require-dev": {
		"dealerdirect/phpcodesniffer-composer-installer": "^1.0",
		"netherphp/standards": "^0.2.9"
	},
	"require": {
		"aspectus/terminal": "^0.1.4",
		"ozdemirburak/iris": "^3.1"
	}
}

test.php

<?php

require('vendor/autoload.php');

use Aspectus\Terminal\Xterm;
use Aspectus\Terminal\Xterm\Event\MouseInputEvent;
use OzdemirBurak\Iris\Color;

use function Amp\async;
use function Amp\delay;

class Roflwalker {

	protected Xterm
	$X;

	protected int
	$Width;

	protected int
	$Height;

	protected int
	$MX = -1;

	protected int
	$MY = -1;

	protected Color\Hex
	$Colour;

	protected int
	$Iter = 0;

	protected float
	$Time = 0.0;

	protected int
	$Framelimit = 60;

	protected int
	$Pace = 4;

	public function
	__Construct(Xterm $X, int $Width, int $Height) {
		$this->X = $X;
		$this->Width = $Width;
		$this->Height = $Height;
		$this->Colour = new Color\Hex('#FF0000');
		$this->Time = microtime(TRUE);

		return;
	}

	public function
	__Destroy() {

		//$this->Reset();
		return;
	}

	public function
	OnMouseInput(MouseInputEvent $Event):
	void {

		$this->MX = $Event->x;
		$this->MY = $Event->y;

		return;
	}

	public function
	Next():
	void {

		$Time = microtime(TRUE);
		$Frametime = ($Time - $this->Time);
		$Framerate = 1 / $Frametime;
		$Framemult = 1 + (1 - ($Framerate / 60));

		if($Frametime < 1 / $this->Framelimit)
		return;

		$PosX = 0;
		$PosY = 0;
		$R = 0;
		$G = 0;
		$B = 0;
		$Spun = 0;
		$Spin = 0;

		while($PosX < $this->Width) {
			$PosY = 0;
			$Spin = (int)(1 * $Framemult);

			$this->Colour = $this->Colour->Spin($Spin);
			$Spun += $Spin;

			$R = hexdec($this->Colour->Red());
			$G = hexdec($this->Colour->Green());
			$B = hexdec($this->Colour->Blue());

			while($PosY < $this->Height) {
				($this->X)
				->RGB($R, $G, $B)
				->MoveCursorTo($PosY, $PosX)
				->Write('#');

				$PosY += 1;
			}

			$PosX += 1;
		}

		($this->X)
		->MoveCursorTo(0, 0)
		->Write(sprintf(
			'Iteration: %d %.2f %.2f ',
			$this->Iter,
			$Framerate,
			$Framemult
		));

		$this->Colour = $this->Colour->Spin(
			(int)($Spun * 0.9)
			* -1
		);

		$this->Iter += 1;
		$this->Time = $Time;
		$this->X->Flush();

		return;
	}

	public function
	Prepare():
	static {

		($this->X)
		->EraseDisplay()
		->BgDefault()
		->Default()
		->SetPrivateModeHideCursor()
		->SetPrivateModeTrackMouseOnPressAndRelease()
		->SetPrivateModeTrackMouseAll()
		//->Subscribe(
		//	MouseInputEvent::class,
		//	$this->OnMouseInput(...)
		//)
		->Flush();

		return $this;
	}

};

class Terminlol {

	protected Aspectus\Terminal\Xterm
	$X;

	protected int
	$Width;

	protected int
	$Height;

	public function
	__Construct() {

		$this->X = new Aspectus\Terminal\Xterm;
		$this->Width = (int)`tput cols`;
		$this->Height = (int)`tput lines`;

		$this->X
		->Write(sprintf('Ready: %d x %d', $this->Width, $this->Height))
		->Flush();

		return;
	}

	public function
	Run():
	void {

		$Func = async(function () {

			$Game = new Roflwalker($this->X, $this->Width, $this->Height);
			$Game->Prepare();

			while(TRUE) {
				$Game->Next();
				delay(0.0);
			}

			return;
		});

		$Func->Await();
		return;
	}

};

$Term = new Terminlol;
$Term->Run();

Yea been playing around with manual framerate limiter but ended up recreating what delay is. Can't avoid the drift when it happens anyway, except if you suspend every other line.

I will put a framebuffer implementation in Aspectus eventually (i had a different design and now im left with "migrating" the code to the new one). Said framebuffer you COULD use a tick method (repeat) that renders it, in the meantime, things write on it. But that does not save you from drift when the processing is taking longer than the interval.