Added THR file optimization script

Author: markroland

readme.md

@@ -54,6 +54,18 @@ Pattern classes are made up of at least 4 methods:
 
 Once you've completed your design, submit a Pull Request and if it works, I'll merge it in. Thanks in advance!
 
+## Optimize a THR track
+
+When creating tracks, it may be that there are far too many points than necessary - the sand table
+may not be able to render the track with the precision specified. Since each instruction is processed
+this may lead to an unnecessarily slow drawing time. In order to prevent this I have created a THR
+optimization script that uses the drawing devices table and ball size to simplify the path to avoid
+unnecessary drawing steps.
+
+```
+node ./scripts/optimize-thr.mjs {path_to_thr_file}
+```
+
 ## Patterns
 
 - XY Coordinates

scripts/optimize-thr.mjs

@@ -0,0 +1,102 @@
+import fs from 'fs';
+import readline from 'readline';
+import path from 'path';
+
+// Add definition for __dirname in ES modules
+// const __dirname = path.dirname(new URL(import.meta.url).pathname);
+
+// Get file path from command line arguments
+const filePath = process.argv[2];
+
+// Set the environment dimensions
+const ball_diameter_mm = 10;
+const table_diameter_mm = 406;
+
+// Calculate the normalized resolution (where 1.0 is the full radius of the table)
+const norm_distance_threshold = ((0.5 * ball_diameter_mm) / (0.5 * table_diameter_mm)).toFixed(3);
+
+if (!filePath) {
+  console.error('Usage: node optimize-thr.js <path-to-file.thr>');
+  process.exit(1);
+}
+
+console.log(`Ball Diameter: ${ball_diameter_mm}mm`);
+console.log(`Table Diameter: ${table_diameter_mm}mm`);
+console.log(`Normalized Threshold: ${norm_distance_threshold}`);
+
+// Create a readable stream and readline interface
+const rl = readline.createInterface({
+  input: fs.createReadStream(filePath),
+  crlfDelay: Infinity
+});
+
+let prevTheta = null;
+let prevRho = null;
+let old_instruction_count = 0;
+let new_instruction_count = 0;
+
+let new_path = [];
+
+rl.on('line', (line) => {
+
+  // Preserve comment lines
+  if (line.startsWith('#')) {
+    new_path.push([line]);
+    return;
+  }
+
+  // Skip lines that aren't position data
+  const match = line.match(/^([+-]?\d*\.?\d+)\s+([+-]?\d*\.?\d+)/);
+  if (!match) {
+    new_path.push([line]);
+    return;
+  }
+
+  // Count old lines
+  old_instruction_count++;
+
+  // Parse data from line
+  const [, num1Str, num2Str] = match;
+  const theta = parseFloat(num1Str);
+  const rho = parseFloat(num2Str);
+
+  // First data point
+  if (prevTheta === null && prevRho === null) {
+    new_path.push([theta, rho]);
+    new_instruction_count++;
+    prevTheta = theta;
+    prevRho = rho;
+    return;
+  }
+
+  // Calculate distance between two polar points
+  const distance = Math.sqrt(
+    prevRho * prevRho + rho * rho - 2 * prevRho * rho * Math.cos(theta - prevTheta)
+  );
+
+  if (distance > norm_distance_threshold) {
+    new_path.push([theta, rho]);
+    new_instruction_count++;
+    prevTheta = theta;
+    prevRho = rho;
+  }
+});
+
+rl.on('close', () => {
+
+  // Transform new_path: combine each coordinate pair into a string with a space separator.
+  // Comments are already stored as single-element arrays, so they'll just be output as-is
+  const combinedPath = new_path.map(pair => pair.length === 1 ? pair[0] : pair.join(' '));
+
+  // Determine output file path: same directory as input file but with a .opt.thr extension.
+  const parsedPath = path.parse(filePath);
+  const outputFilePath = path.join(parsedPath.dir, parsedPath.name + '.opt.thr');
+
+  // Write one line per coordinate pair with "number space number"
+  fs.writeFileSync(outputFilePath, combinedPath.join('\n'), 'utf8');
+
+  // Print info
+  console.log(`Original Point Count: ${old_instruction_count.toLocaleString()}`);
+  console.log(`Optimized Point Count: ${new_instruction_count.toLocaleString()}`);
+  console.log(`Saved to ${outputFilePath}`);
+});