Add: make modal windows update more smooth

Basically, modal windows had their own thread-locking for what
drawing was possible. This is a bit nonsense now we have a
game-thread. And it makes much more sense to do things like
NewGRFScan and GenerateWorld in the game-thread, and not in a
thread next to the game-thread.

This commit changes that: it removes the threads for NewGRFScan
and GenerateWorld, and just runs the code in the game-thread.
On regular intervals it allows the draw-thread to do a tick,
which gives a much smoother look and feel.

It does slow down NewGRFScan and GenerateWorld ever so slightly
as it spends more time on drawing. But the slowdown is not
measureable on my machines (with 700+ NewGRFs / 4kx4k map and
a Debug build).

Running without a game-thread means NewGRFScan and GenerateWorld
are now blocking.

1 files changed, 7 insertions, 19 deletions

diff --git a/src/genworld_gui.cpp b/src/genworld_gui.cpp
index bf4d327a7..f26d43ac3 100644
--- a/src/genworld_gui.cpp
+++ b/src/genworld_gui.cpp
@@ -29,6 +29,7 @@
 #include "error.h"
 #include "newgrf_townname.h"
 #include "townname_type.h"
+#include "video/video_driver.hpp"
 
 #include "widgets/genworld_widget.h"
 
@@ -1312,10 +1313,10 @@ static void _SetGeneratingWorldProgress(GenWorldProgress cls, uint progress, uin
 	static_assert(lengthof(percent_table) == GWP_CLASS_COUNT + 1);
 	assert(cls < GWP_CLASS_COUNT);
 
-	/* Do not run this function if we aren't in a thread */
-	if (!IsGenerateWorldThreaded() && !_network_dedicated) return;
-
-	if (IsGeneratingWorldAborted()) HandleGeneratingWorldAbortion();
+	if (IsGeneratingWorldAborted()) {
+		HandleGeneratingWorldAbortion();
+		return;
+	}
 
 	if (total == 0) {
 		assert(_gws.cls == _generation_class_table[cls]);
@@ -1328,10 +1329,6 @@ static void _SetGeneratingWorldProgress(GenWorldProgress cls, uint progress, uin
 		_gws.percent = percent_table[cls];
 	}
 
-	/* Don't update the screen too often. So update it once in every once in a while... */
-	if (!_network_dedicated && std::chrono::steady_clock::now() < _gws.next_update) return;
-	_gws.next_update = std::chrono::steady_clock::now() + std::chrono::milliseconds(MODAL_PROGRESS_REDRAW_TIMEOUT);
-
 	/* Percentage is about the number of completed tasks, so 'current - 1' */
 	_gws.percent = percent_table[cls] + (percent_table[cls + 1] - percent_table[cls]) * (_gws.current == 0 ? 0 : _gws.current - 1) / _gws.total;
 
@@ -1350,21 +1347,12 @@ static void _SetGeneratingWorldProgress(GenWorldProgress cls, uint progress, uin
 		DEBUG(net, 1, "Map generation percentage complete: %d", _gws.percent);
 		last_percent = _gws.percent;
 
-		/* Don't continue as dedicated never has a thread running */
 		return;
 	}
 
 	SetWindowDirty(WC_MODAL_PROGRESS, 0);
-	MarkWholeScreenDirty();
-
-	/* Release the rights to the map generator, and acquire the rights to the
-	 * paint thread. The 'other' thread already has the paint thread rights so
-	 * this ensures us that we are waiting until the paint thread is done
-	 * before we reacquire the mapgen rights */
-	_modal_progress_work_mutex.unlock();
-	_modal_progress_paint_mutex.lock();
-	_modal_progress_work_mutex.lock();
-	_modal_progress_paint_mutex.unlock();
+
+	VideoDriver::GetInstance()->GameLoopPause();
 }
 
 /**