uncapped FPS: fix viewport chopiness and reset after park load

src/game.c

@@ -670,6 +670,7 @@ int game_load_sv6(const char *path)
 	reset_loaded_objects();
 	map_update_tile_pointers();
 	reset_0x69EBE4();
+	gOpenRCT2ResetFrameSmoothing = true;
 	return 1;
 }
 

src/interface/window.c

@@ -156,6 +156,13 @@ void window_dispatch_update_all()
 	RCT2_CALLPROC_EBPSAFE(0x006EE411);	// handle_text_input
 }
 
+void window_update_all_viewports()
+{
+	for (rct_window *w = g_window_list; w < RCT2_NEW_WINDOW; w++)
+		if (w->viewport != NULL)
+			viewport_update_position(w);
+}
+
 /**
  * 
  *  rct2: 0x006E77A1
@@ -169,10 +176,7 @@ void window_update_all()
 		return;
 
 	gfx_draw_all_dirty_blocks();
-
-	for (w = g_window_list; w < RCT2_NEW_WINDOW; w++)
-		if (w->viewport != NULL)
-			viewport_update_position(w);
+	window_update_all_viewports();
 
 	// 1000 tick update
 	RCT2_GLOBAL(0x009DEB7C, sint16) += RCT2_GLOBAL(0x009DE588, sint16);

src/interface/window.h

@@ -459,6 +459,7 @@ extern rct_window* g_window_list;
 extern ride_list_item _window_track_list_item;
 
 void window_dispatch_update_all();
+void window_update_all_viewports();
 void window_update_all();
 rct_window *window_create(int x, int y, int width, int height, uint32 *event_handlers, rct_windowclass cls, uint16 flags);
 rct_window *window_create_auto_pos(int width, int height, uint32 *event_handlers, rct_windowclass cls, uint16 flags);

src/openrct2.c

@@ -42,6 +42,10 @@ bool gOpenRCT2Headless = false;
 
 bool gOpenRCT2ShowChangelog;
 
+// This needs to be set when a park is loaded. It could also be used to reset other important states, it should then be renamed
+// to something more general.
+bool gOpenRCT2ResetFrameSmoothing = false;
+
 /** If set, will end the OpenRCT2 game loop. Intentially private to this module so that the flag can not be set back to 0. */
 int _finished;
 
@@ -231,6 +235,21 @@ void openrct2_dispose()
 	platform_free();
 }
 
+/**
+ * Determines whether its worth tweening a sprite or not when frame smoothing is on.
+ */
+static bool sprite_should_tween(rct_sprite *sprite)
+{
+	if (sprite->unknown.linked_list_type_offset == SPRITE_LINKEDLIST_OFFSET_VEHICLE)
+		return true;
+	if (sprite->unknown.linked_list_type_offset == SPRITE_LINKEDLIST_OFFSET_PEEP)
+		return true;
+	if (sprite->unknown.linked_list_type_offset == SPRITE_LINKEDLIST_OFFSET_UNKNOWN)
+		return true;
+
+	return false;
+}
+
 /**
  * Run the main game loop until the finished flag is set at 40fps (25ms interval).
  */
@@ -250,6 +269,7 @@ static void openrct2_loop()
 		if (gConfigGeneral.uncap_fps) {
 			currentTick = SDL_GetTicks();
 			if (!uncappedinitialized) {
+				// Reset sprite locations
 				uncapTick = SDL_GetTicks();
 				for (uint16 i = 0; i < MAX_SPRITES; i++) {
 					spritelocations1[i].x = spritelocations2[i].x = g_sprite_list[i].unknown.x;
@@ -258,28 +278,51 @@ static void openrct2_loop()
 				}
 				uncappedinitialized = 1;
 			}
+
 			while (uncapTick <= currentTick && currentTick - uncapTick > 25) {
+				// Get the original position of each sprite
 				for (uint16 i = 0; i < MAX_SPRITES; i++) {
 					spritelocations1[i].x = g_sprite_list[i].unknown.x;
 					spritelocations1[i].y = g_sprite_list[i].unknown.y;
 					spritelocations1[i].z = g_sprite_list[i].unknown.z;
 				}
+				
+				// Update the game so the sprite positions update
 				rct2_update();
+				if (gOpenRCT2ResetFrameSmoothing) {
+					gOpenRCT2ResetFrameSmoothing = false;
+					continue;
+				}
+
+				// Get the next position of each sprite
 				for (uint16 i = 0; i < MAX_SPRITES; i++) {
 					spritelocations2[i].x = g_sprite_list[i].unknown.x;
 					spritelocations2[i].y = g_sprite_list[i].unknown.y;
 					spritelocations2[i].z = g_sprite_list[i].unknown.z;
 				}
+
 				uncapTick += 25;
 			}
+
+			// Tween the position of each sprite from the last position to the new position based on the time between the last
+			// tick and the next tick.
 			float nudge = 1 - ((float)(currentTick - uncapTick) / 25);
 			for (uint16 i = 0; i < MAX_SPRITES; i++) {
-				if (!(g_sprite_list[i].unknown.linked_list_type_offset == SPRITE_LINKEDLIST_OFFSET_VEHICLE || g_sprite_list[i].unknown.linked_list_type_offset == SPRITE_LINKEDLIST_OFFSET_PEEP || g_sprite_list[i].unknown.linked_list_type_offset == SPRITE_LINKEDLIST_OFFSET_UNKNOWN)) {
+				if (!sprite_should_tween(&g_sprite_list[i]))
 					continue;
-				}
-				sprite_move(spritelocations2[i].x + (sint16)((spritelocations1[i].x - spritelocations2[i].x) * nudge), spritelocations2[i].y + (sint16)((spritelocations1[i].y - spritelocations2[i].y) * nudge), spritelocations2[i].z + (sint16)((spritelocations1[i].z - spritelocations2[i].z) * nudge), &g_sprite_list[i]);
+
+				sprite_move(
+					spritelocations2[i].x + (sint16)((spritelocations1[i].x - spritelocations2[i].x) * nudge),
+					spritelocations2[i].y + (sint16)((spritelocations1[i].y - spritelocations2[i].y) * nudge),
+					spritelocations2[i].z + (sint16)((spritelocations1[i].z - spritelocations2[i].z) * nudge),
+					&g_sprite_list[i]
+				);
 				invalidate_sprite(&g_sprite_list[i]);
 			}
+
+			// Viewports need to be updated to reduce chopiness of those which follow sprites
+			window_update_all_viewports();
+
 			platform_process_messages();
 			rct2_draw();
 			platform_draw();
@@ -288,10 +331,12 @@ static void openrct2_loop()
 				fps = 0;
 				secondTick = SDL_GetTicks();
 			}
+
+			// Restore the real positions of the sprites so they aren't left at the mid-tween positions
 			for (uint16 i = 0; i < MAX_SPRITES; i++) {
-				if (!(g_sprite_list[i].unknown.linked_list_type_offset == SPRITE_LINKEDLIST_OFFSET_VEHICLE || g_sprite_list[i].unknown.linked_list_type_offset == SPRITE_LINKEDLIST_OFFSET_PEEP || g_sprite_list[i].unknown.linked_list_type_offset == SPRITE_LINKEDLIST_OFFSET_UNKNOWN)) {
+				if (!sprite_should_tween(&g_sprite_list[i]))
 					continue;
-				}
+
 				sprite_move(spritelocations2[i].x, spritelocations2[i].y, spritelocations2[i].z, &g_sprite_list[i]);
 			}
 		} else {
@@ -307,7 +352,10 @@ static void openrct2_loop()
 			lastTick = currentTick;
 
 			platform_process_messages();
+
 			rct2_update();
+			gOpenRCT2ResetFrameSmoothing = false;
+
 			rct2_draw();
 			platform_draw();
 		}

src/openrct2.h

@@ -35,6 +35,7 @@ extern char gOpenRCT2StartupActionPath[512];
 extern char gExePath[MAX_PATH];
 extern bool gOpenRCT2Headless;
 extern bool gOpenRCT2ShowChangelog;
+extern bool gOpenRCT2ResetFrameSmoothing;
 
 bool openrct2_initialise();
 void openrct2_launch();

src/scenario.c

@@ -30,6 +30,7 @@
 #include "management/research.h"
 #include "management/news_item.h"
 #include "object.h"
+#include "openrct2.h"
 #include "peep/staff.h"
 #include "platform/platform.h"
 #include "ride/ride.h"
@@ -178,6 +179,7 @@ int scenario_load(const char *path)
 			reset_loaded_objects();
 			map_update_tile_pointers();
 			reset_0x69EBE4();
+			gOpenRCT2ResetFrameSmoothing = true;
 			return 1;
 		}