Added a tool to visualise behaviour of ChunkSelector

I actually intended to write a tool for debugging generation, but it turns out this, as an intermediary step, is also useful and a whole bunch of fun to play with.

tools/simulate-chunk-selector.php

@@ -0,0 +1,171 @@
+<?php
+
+declare(strict_types=1);
+
+namespace pocketmine\tools\simulate_chunk_selector;
+
+use pocketmine\player\ChunkSelector;
+use pocketmine\utils\AssumptionFailedError;
+use pocketmine\world\format\Chunk;
+use pocketmine\world\World;
+use Webmozart\PathUtil\Path;
+use function assert;
+use function count;
+use function dirname;
+use function fwrite;
+use function getopt;
+use function imagearc;
+use function imagecolorallocate;
+use function imagecreatetruecolor;
+use function imagefill;
+use function imagefilledrectangle;
+use function imagepng;
+use function imagerectangle;
+use function imagesavealpha;
+use function is_dir;
+use function is_string;
+use function mkdir;
+use function realpath;
+use function scandir;
+use function str_pad;
+use function strval;
+use const SCANDIR_SORT_NONE;
+use const STDERR;
+use const STR_PAD_LEFT;
+
+require dirname(__DIR__) . '/vendor/autoload.php';
+
+function newImage(int $scale, int $radius) : \GdImage{
+	$image = imagecreatetruecolor($scale * $radius * 2, $scale * $radius * 2);
+	if($image === false){
+		throw new AssumptionFailedError();
+	}
+	imagesavealpha($image, true);
+
+	$black = imagecolorallocate($image, 0, 0, 0);
+	if($black === false){
+		throw new AssumptionFailedError();
+	}
+	imagefill($image, 0, 0, $black);
+	return $image;
+}
+
+function render(int $radius, int $baseX, int $baseZ, int $chunksPerStep, int $scale, \GdImage $image, int $chunkColor, int $offsetX, int $offsetZ, string $outputFolder) : void{
+	echo "Render start: radius $radius, chunks per step $chunksPerStep\n";
+	$iterator = (new ChunkSelector())->selectChunks($radius, $baseX, $baseZ);
+
+	$middleOffsetX = $scale * ($radius + $offsetX);
+	$middleOffsetZ = $scale * ($radius + $offsetZ);
+
+	$frame = 0;
+	$seen = [];
+	while($iterator->valid()){
+		$frame++;
+
+		$black = imagecolorallocate($image, 0, 0, 0);
+		$yellow = imagecolorallocate($image, 255, 255, 51);
+		$red = imagecolorallocate($image, 255, 0, 0);
+		if($black === false || $yellow === false || $red === false) throw new AssumptionFailedError();
+
+		for($i = 0; $i < $chunksPerStep; ++$i){
+			$chunkHash = $iterator->current();
+			if(!isset($seen[$chunkHash])){
+				$color = $chunkColor;
+				$seen[$chunkHash] = true;
+			}else{
+				$color = $yellow;
+			}
+			World::getXZ($chunkHash, $chunkX, $chunkZ);
+			$imageX = $middleOffsetX + (($chunkX - $baseX) * $scale);
+			$imageZ = $middleOffsetZ + (($chunkZ - $baseZ) * $scale);
+
+			imagefilledrectangle($image, $imageX, $imageZ, $imageX + $scale, $imageZ + $scale, $color);
+			imagerectangle($image, $imageX, $imageZ, $imageX + $scale, $imageZ + $scale, $black);
+
+			$iterator->next();
+			if(!$iterator->valid()){
+				break;
+			}
+		}
+		imagearc($image, $middleOffsetX, $middleOffsetZ, $radius * $scale * 2, $radius * $scale * 2, 0, 360, $red);
+
+		imagepng($image, Path::join($outputFolder, "frame" . str_pad(strval($frame), 5, "0", STR_PAD_LEFT) . ".png"));
+		echo "\rRendered step $frame";
+	}
+	echo "\n";
+}
+
+$radius = null;
+$baseX = 10000 >> Chunk::COORD_BIT_SIZE;
+$baseZ = 10000 >> Chunk::COORD_BIT_SIZE;
+
+$nChunksPerStep = 32;
+$scale = 10;
+
+if(count(getopt("", ["help"])) !== 0){
+	echo "Required parameters:\n";
+	echo "--output=path/to/dir: Output folder to put the generated images into (will attempt to create if it doesn't exist)\n";
+	echo "--radius=N: Radius of chunks to render (default $radius)\n";
+	echo "\n";
+	echo "Optional parameters:\n";
+	echo "--baseX=N: Base X coordinate to use for simulation (default $baseX\n";
+	echo "--baseZ=N: Base Z coordinate to use for simulation (default $baseZ)\n";
+	echo "--scale=N: Height/width of square of pixels to use for each chunk (default $scale)\n";
+	echo "--chunksPerStep=N: Number of chunks to process in each frame (default $nChunksPerStep)\n";
+	exit(0);
+}
+
+foreach(getopt("", ["radius:", "baseX:", "baseZ:", "scale:", "chunksPerStep:"]) as $name => $value){
+	if(!is_string($value) || (string) ((int) $value) !== $value){
+		fwrite(STDERR, "Value for --$name must be an integer\n");
+		exit(1);
+	}
+	$value = (int) $value;
+	match($name){
+		"radius" => ($radius = $value),
+		"baseX" => ($baseX = $value),
+		"baseZ" => ($baseZ = $value),
+		"scale" => ($scale = $value),
+		"chunksPerStep" => ($nChunksPerStep = $value),
+		default => throw new AssumptionFailedError("getopt() returned unknown option")
+	};
+}
+if($radius === null){
+	fwrite(STDERR, "Please specify a radius using --radius\n");
+	exit(1);
+}
+
+$outputDirectory = null;
+foreach(getopt("", ["output:"]) as $name => $value){
+	assert($name === "output");
+	if(!is_string($value)){
+		fwrite(STDERR, "Value for --$name must be a string\n");
+		exit(1);
+	}
+	if(!@mkdir($value) && !is_dir($value)){
+		fwrite(STDERR, "Output directory $value could not be created\n");
+		exit(1);
+	}
+	$files = scandir($value, SCANDIR_SORT_NONE);
+	if($files !== false && count($files) > 2){ //always returns . and ..
+		fwrite(STDERR, "Output directory $value is not empty\n");
+		exit(1);
+	}
+	$realPath = realpath($value);
+	if($realPath === false){
+		throw new AssumptionFailedError();
+	}
+	$outputDirectory = $realPath;
+}
+if($outputDirectory === null){
+	fwrite(STDERR, "Please specify an output directory using --output\n");
+	exit(1);
+}
+$image = newImage($scale, $radius);
+
+$black = imagecolorallocate($image, 0, 0, 0);
+$green = imagecolorallocate($image, 0, 220, 0);
+if($black === false || $green === false){
+	throw new AssumptionFailedError();
+}
+render($radius, $baseX, $baseZ, $nChunksPerStep, $scale, $image, $green, 0, 0, $outputDirectory);