(main)+kill threads when avalanche has completed

After the so-called "avalanche", where the fractal has finished
forming as there are no more candidates for toppling, we no longer
need the threads to be working.  As an intensive operation, it makes
no sense to continue processing when we are sure there is no further
dynamic behaviour possible.

Using a tick based solution, every DELTA ticks we check if the
avalanche is completed.  If so, we clean up all the threads AND ensure
that we no longer need to be checking for avalanches.

1 files changed, 30 insertions, 3 deletions

diff --git a/main.c b/main.c
index dd8a1ac..65a6954 100644
--- a/main.c
+++ b/main.c
@@ -56,9 +56,19 @@ void *compute_thread(void *input)
   return NULL;
 }
 
-int main(void)
+bool completed_avalanche(state_t *state)
 {
-  state_t state    = {NULL, 512, 512, 0, true, pow(2, 20)};
+  for (size_t i = 0; i < state->dwidth; ++i)
+    for (size_t j = 0; j < state->dwidth; ++j)
+      if (state->data[(i * state->dwidth) + j] >= 4)
+        return false;
+  return true;
+}
+
+int main(int argc, char *argv[])
+{
+  // Setup "default" state
+  state_t state    = {NULL, 512, 512, 0, true, pow(2, 16)};
   state.data       = calloc(state.dwidth * state.dwidth, sizeof(*state.data));
   state.multiplier = state.window_len / state.dwidth;
   state.data[(state.dwidth * state.dwidth / 2) + (state.dwidth / 2)] =
@@ -85,7 +95,9 @@ int main(void)
   InitWindow(state.window_len, state.window_len, "Abelian sand pile");
   SetTargetFPS(60);
 
-  while (!WindowShouldClose())
+  const int DELTA = 100;
+  bool done       = false;
+  for (uint64_t ticks = 0, prev_ticks = 0; !WindowShouldClose(); ++ticks)
   {
     if (IsKeyPressed(KEY_UP) || IsKeyDown(KEY_UP))
     {
@@ -108,6 +120,21 @@ int main(void)
         camera.zoom = zoom;
     }
 
+    if (ticks - prev_ticks > DELTA && !done)
+    {
+      printf("Checking if avalanche is complete!\n");
+      if (completed_avalanche(&state))
+      {
+        state.thread_alive = false;
+        pthread_join(thread_a, NULL);
+        pthread_join(thread_b, NULL);
+        pthread_join(thread_c, NULL);
+        pthread_join(thread_d, NULL);
+        done = true;
+      }
+      prev_ticks = ticks;
+    }
+
     if (IsMouseButtonDown(MOUSE_BUTTON_LEFT))
     {
       Vector2 delta = Vector2Scale(GetMouseDelta(), -1.0f / camera.zoom);