Initial commit — Amirine Cosplay Lights

Arduino Uno + WS2812B LED strip controller with a text-based lightshow
system. Shows are defined as .txt files (hex color + fade duration per step),
converted to PROGMEM headers by convert_all.py, and navigated at runtime
via a debounced button (tap/double-tap/hold). BSD 2-Clause license.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

arduino/cosplay_lights/cosplay_lights.ino

@@ -0,0 +1,113 @@
+/*
+ * Amirine Cosplay Lights
+ *
+ * Plays lightshows defined in shows.h on a WS2812B LED strip.
+ * A single button navigates between shows:
+ *   1 tap  — next show
+ *   2 taps — previous show
+ *   hold   — reset to show 0 (slow blue pulse)
+ *
+ * To add or update shows:
+ *   1. Add or edit a .txt file in converter/shows/
+ *   2. Run:   make shows
+ *   3. Run:   make upload
+ *
+ * Required library: FastLED  (Sketch > Include Library > Manage Libraries)
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "config.h"
+#include "led_controller.h"
+#include "button.h"
+#include "shows.h"
+
+// Milliseconds between LED updates. 16ms ≈ 60 refreshes/second.
+#define UPDATE_INTERVAL_MS  16
+
+// ---- Color math --------------------------------------------------------
+
+// Interpolate a single 8-bit channel from a to b by ratio t (0.0 – 1.0).
+static uint8_t lerp_channel(uint8_t a, uint8_t b, float t) {
+    return (uint8_t)(a + (b - a) * t);
+}
+
+// Blend two colors: t=0.0 returns 'from', t=1.0 returns 'to'.
+static CRGB blend_colors(CRGB from, CRGB to, float t) {
+    return CRGB(
+        lerp_channel(from.r, to.r, t),
+        lerp_channel(from.g, to.g, t),
+        lerp_channel(from.b, to.b, t)
+    );
+}
+
+// ---- Playback state ----------------------------------------------------
+
+static uint8_t  s_show_index  = 0;           // which show is active (index into SHOWS[])
+static ShowDef  s_show;                       // active show, read from PROGMEM once on load
+static uint16_t s_step_index  = 0;           // current step within the active show
+static uint32_t s_step_start  = 0;           // millis() when this step began
+static CRGB     s_from_color  = CRGB::Black; // color at the start of this transition
+
+// Load show at 'index', resetting playback to the first step.
+static void load_show(uint8_t index) {
+    s_show_index = index;
+    s_show       = read_show_def(&SHOWS[index]);
+    s_step_index = 0;
+    s_step_start = millis();
+    s_from_color = CRGB::Black;
+}
+
+// How far through the current step we are (0.0 – 1.0).
+// Returns 1.0 immediately for instant steps (duration_ms == 0).
+static float step_progress(const Step& step) {
+    if (step.duration_ms == 0) return 1.0f;
+    uint32_t elapsed = millis() - s_step_start;
+    float t = (float)elapsed / step.duration_ms;
+    return (t < 1.0f) ? t : 1.0f;
+}
+
+// Complete the current step and advance to the next (loops at end of show).
+static void advance_step(CRGB reached_color) {
+    s_from_color = reached_color;
+    s_step_index = (s_step_index + 1) % s_show.length;
+    s_step_start = millis();
+}
+
+// ---- Arduino entry points ----------------------------------------------
+
+void setup() {
+    leds_begin();
+    button_begin(BUTTON_PIN);
+    load_show(0);   // start on show 0 — slow blue pulse
+}
+
+void loop() {
+    // ---- Button navigation ----
+    ButtonEvent evt = button_update();
+    if (evt == BTN_TAP) {
+        // Next show, wrapping around to 0 after the last one.
+        load_show((s_show_index + 1) % SHOW_COUNT);
+    }
+    if (evt == BTN_DOUBLE_TAP) {
+        // Previous show, wrapping around to the last one from show 0.
+        load_show((s_show_index + SHOW_COUNT - 1) % SHOW_COUNT);
+    }
+    if (evt == BTN_HOLD) {
+        // Reset to show 0 (blue pulse) from any position.
+        load_show(0);
+    }
+
+    // ---- Playback ----
+    Step  step    = read_step(&s_show.steps[s_step_index]);
+    CRGB  to      = CRGB(step.r, step.g, step.b);
+    float t       = step_progress(step);
+
+    leds_apply_color(blend_colors(s_from_color, to, t));
+    leds_show();
+
+    if (t >= 1.0f) {
+        advance_step(to);
+    }
+
+    delay(UPDATE_INTERVAL_MS);
+}