feat: Add --seek command line option for fast-forward debugging

This feature allows developers to jump to a specific time in the demo sequence (e.g., './demo64k --seek 10.5'). It simulates the game logic, audio state (rendering silent buffers), and visual physics (compute shaders) from t=0 up to the target time before starting real-time playback. Audio initialization is refactored to separate device init and start.

1 files changed, 36 insertions, 8 deletions

diff --git a/src/main.cc b/src/main.cc
index fb0b412..75143c0 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -130,12 +130,15 @@ float* generate_tone(float *buffer, float freq) {
 
 int main(int argc, char **argv) {
   bool fullscreen_enabled = false;
+  double seek_time = 0.0;
 
 #ifndef STRIP_ALL
   for (int i = 1; i < argc; ++i) {
     if (strcmp(argv[i], "--fullscreen") == 0) {
       fullscreen_enabled = true;
-      break;
+    } else if (strcmp(argv[i], "--seek") == 0 && i + 1 < argc) {
+      seek_time = atof(argv[i + 1]);
+      i++;
     }
   }
 #else
@@ -166,12 +169,9 @@ int main(int argc, char **argv) {
   double last_beat_time = 0.0;
   int beat_count = 0;
 
-  while (!platform_should_close()) {
-    platform_poll();
-
-    double current_time = platform_get_time();
-    if (current_time - last_beat_time > SECONDS_PER_BEAT / 2.0) { // 8th notes
-      last_beat_time = current_time;
+  auto update_game_logic = [&](double t) {
+    if (t - last_beat_time > SECONDS_PER_BEAT / 2.0) { // 8th notes
+      last_beat_time = t; // Sync to t
 
       const int step = beat_count % 16;
 
@@ -203,6 +203,34 @@ int main(int argc, char **argv) {
 
       ++beat_count;
     }
+  };
+
+#ifndef STRIP_ALL
+  if (seek_time > 0.0) {
+    printf("Seeking to %.2f seconds...\n", seek_time);
+    
+    // Simulate audio/game logic
+    // We step at ~60hz
+    const double step = 1.0/60.0;
+    for (double t = 0.0; t < seek_time; t += step) {
+      update_game_logic(t);
+      audio_render_silent((float)step);
+    }
+    
+    // Simulate Visuals
+    gpu_simulate_until((float)seek_time);
+  }
+#endif
+
+  // Start real audio
+  audio_start();
+
+  while (!platform_should_close()) {
+    platform_poll();
+
+    double current_time = platform_get_time() + seek_time; // Offset logic time
+    
+    update_game_logic(current_time);
 
     int width, height;
     glfwGetFramebufferSize(platform_get_window(), &width, &height);
@@ -221,4 +249,4 @@ int main(int argc, char **argv) {
   gpu_shutdown();
   platform_shutdown();
   return 0;
-}
+}
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