Add: draw the screen at a steady pace, also during fast-forward

During fast-forward, the game was drawing as fast as it could. This
means that the fast-forward was limited also by how fast we could
draw, something that people in general don't expect.

To give an extreme case, if you are fully zoomed out on a busy
map, fast-forward would be mostly limited because of the time it
takes to draw the screen.

By decoupling the draw-tick and game-tick, we can keep the pace
of the draw-tick the same while speeding up the game-tick. To use
the extreme case as example again, if you are fully zoomed out
now, the screen only redraws 33.33 times per second, fast-forwarding
or not. This means fast-forward is much more likely to go at the
same speed, no matter what you are looking at.

1 files changed, 15 insertions, 9 deletions

diff --git a/src/video/cocoa/cocoa_v.mm b/src/video/cocoa/cocoa_v.mm
index c9e6768a8..d065630b7 100644
--- a/src/video/cocoa/cocoa_v.mm
+++ b/src/video/cocoa/cocoa_v.mm
@@ -636,7 +636,8 @@ void VideoDriver_Cocoa::GameLoop()
 {
 	auto cur_ticks = std::chrono::steady_clock::now();
 	auto last_realtime_tick = cur_ticks;
-	auto next_tick = cur_ticks;
+	auto next_game_tick = cur_ticks;
+	auto next_draw_tick = cur_ticks;
 
 	for (;;) {
 		@autoreleasepool {
@@ -672,8 +673,14 @@ void VideoDriver_Cocoa::GameLoop()
 				last_realtime_tick += delta;
 			}
 
-			if (cur_ticks >= next_tick || (_fast_forward && !_pause_mode)) {
-				next_tick = cur_ticks + std::chrono::milliseconds(MILLISECONDS_PER_TICK);
+			if (cur_ticks >= next_game_tick || (_fast_forward && !_pause_mode)) {
+				next_game_tick = cur_ticks + std::chrono::milliseconds(MILLISECONDS_PER_TICK);
+
+				::GameLoop();
+			}
+
+			if (cur_ticks >= next_draw_tick) {
+				next_draw_tick = cur_ticks + std::chrono::milliseconds(MILLISECONDS_PER_TICK);
 
 				bool old_ctrl_pressed = _ctrl_pressed;
 
@@ -682,16 +689,15 @@ void VideoDriver_Cocoa::GameLoop()
 
 				if (old_ctrl_pressed != _ctrl_pressed) HandleCtrlChanged();
 
-				::GameLoop();
-
+				InputLoop();
 				UpdateWindows();
 				this->CheckPaletteAnim();
+
 				this->Draw();
-			} else {
+			}
+
+			if (!_fast_forward || _pause_mode) {
 				CSleep(1);
-				NetworkDrawChatMessage();
-				DrawMouseCursor();
-				this->Draw();
 			}
 		}
 	}