From a016a156e76f7394c5632da325ab0b453cfb3b37 Mon Sep 17 00:00:00 2001
From: Paweł Redman <pawel.redman@gmail.com>
Date: Mon, 26 Mar 2018 14:19:50 +0200
Subject: Independent game timing.

---
 src/game/game.cpp | 65 ++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 45 insertions(+), 20 deletions(-)

(limited to 'src/game/game.cpp')

diff --git a/src/game/game.cpp b/src/game/game.cpp
index f76b478..44ea95d 100644
--- a/src/game/game.cpp
+++ b/src/game/game.cpp
@@ -92,6 +92,8 @@ void state_t::start(void)
 	soldier = new unit_soldier_t(this);
 	soldier->place(&world, v2f_t(2.5, 0.5));
 	select(rectf_t(v2f_t(0.5, 0.5), v2f_t(2.5, 0.5)));
+
+	resume();
 }
 
 void state_t::stop(void)
@@ -179,34 +181,57 @@ void state_t::spawn_soldier(v2f_t x)
 		soldier->destroy();
 }
 
-void state_t::tick(double now_, double dt_)
+void state_t::pause(void)
+{
+	paused = true;
+}
+
+void state_t::resume(void)
+{
+	t0 = nclock();
+	frames_since_t0 = 0;
+
+	paused = false;
+}
+
+
+#define TIME_DELTA ((ntime_t)1000000000 / 60)
+
+void state_t::tick(ntime_t time_)
 {
-	union {
-		double d;
-		uint32_t i;
-	} u;
+	size_t target, frames_this_tick = 0;
 
 	if (paused)
 		return;
 
-	if (dt > 0.05)
-		dt = 0.05;
-	else
-		dt = dt_;
+	target = (time_ - t0) / TIME_DELTA;
+
+	while (frames_since_t0 < target) {
+		// FIXME: Is this non-deterministic enough?
+		dice_prng.seed(dice_prng.next() ^ time);
 
-	now += dt;
+		// setting up old variables (refactor them out eventually)
+		now = time * 1.0e-9;
+		dt = TIME_DELTA * 1.0e-9;
 
-	// FIXME: Is this non-deterministic enough?
-	u.d = now;
-	dice_prng.seed(dice_prng.next() ^ u.i);
-	u.d = dt;
-	dice_prng.seed(dice_prng.next() ^ u.i);
+		// on_think can insert/erase elements of awake_entities so iterate
+		// over a copy of it.
+		auto copy = awake_entities;
+		for (entity_t *ent : copy)
+			ent->on_think();
 
-	// on_think can insert/erase elements of awake_entities so iterate
-	// over a copy of it.
-	auto copy = awake_entities;
-	for (entity_t *ent : copy)
-		ent->on_think();
+		frames++;
+		frames_since_t0++;
+		frames_this_tick++;
+		time += TIME_DELTA;
+
+		if (frames_this_tick == 3) {
+			t0 = time_;
+			frames_since_t0 = 0;
+			frames_behind++;
+			break;
+		}
+	}
 }
 
 die_t::die_t(size_t sides_)
-- 
cgit