Improve level-up animation and unit audio assets

scripts/generate-sfx.mjs

@@ -0,0 +1,78 @@
+import { mkdir, writeFile } from 'node:fs/promises';
+import { dirname, join } from 'node:path';
+
+const sampleRate = 44100;
+const outputPath = join('src', 'assets', 'audio', 'sfx', 'level-up.wav');
+
+function envelope(time, start, duration) {
+  const local = time - start;
+  if (local < 0 || local > duration) {
+    return 0;
+  }
+  const attack = 0.018;
+  const release = 0.22;
+  if (local < attack) {
+    return local / attack;
+  }
+  if (local > duration - release) {
+    return Math.max(0, (duration - local) / release);
+  }
+  return 1;
+}
+
+function tone(time, frequency, start, duration, gain, wave = 'sine') {
+  const amp = envelope(time, start, duration) * gain;
+  if (amp <= 0) {
+    return 0;
+  }
+  const phase = Math.PI * 2 * frequency * (time - start);
+  if (wave === 'triangle') {
+    return amp * (2 / Math.PI) * Math.asin(Math.sin(phase));
+  }
+  return amp * Math.sin(phase);
+}
+
+function sampleAt(time) {
+  const notes = [
+    { start: 0, frequency: 523.25, gain: 0.22, duration: 0.52 },
+    { start: 0.09, frequency: 659.25, gain: 0.2, duration: 0.56 },
+    { start: 0.18, frequency: 783.99, gain: 0.18, duration: 0.62 },
+    { start: 0.31, frequency: 1046.5, gain: 0.16, duration: 0.7 }
+  ];
+
+  const chord = notes.reduce((sum, note) => sum + tone(time, note.frequency, note.start, note.duration, note.gain), 0);
+  const shimmer =
+    tone(time, 1318.51, 0.42, 0.36, 0.055, 'triangle') +
+    tone(time, 1567.98, 0.52, 0.28, 0.042, 'triangle');
+  return Math.max(-0.92, Math.min(0.92, chord + shimmer));
+}
+
+function wavBuffer(samples) {
+  const bytesPerSample = 2;
+  const dataSize = samples.length * bytesPerSample;
+  const buffer = Buffer.alloc(44 + dataSize);
+  buffer.write('RIFF', 0);
+  buffer.writeUInt32LE(36 + dataSize, 4);
+  buffer.write('WAVE', 8);
+  buffer.write('fmt ', 12);
+  buffer.writeUInt32LE(16, 16);
+  buffer.writeUInt16LE(1, 20);
+  buffer.writeUInt16LE(1, 22);
+  buffer.writeUInt32LE(sampleRate, 24);
+  buffer.writeUInt32LE(sampleRate * bytesPerSample, 28);
+  buffer.writeUInt16LE(bytesPerSample, 32);
+  buffer.writeUInt16LE(16, 34);
+  buffer.write('data', 36);
+  buffer.writeUInt32LE(dataSize, 40);
+
+  samples.forEach((sample, index) => {
+    buffer.writeInt16LE(Math.round(sample * 32767), 44 + index * bytesPerSample);
+  });
+  return buffer;
+}
+
+await mkdir(dirname(outputPath), { recursive: true });
+const duration = 1.12;
+const samples = Array.from({ length: Math.floor(sampleRate * duration) }, (_, index) => sampleAt(index / sampleRate));
+await writeFile(outputPath, wavBuffer(samples));
+console.log(`Generated ${outputPath}`);