Plans: Improve performance of viewport plan rendering

src/plans.cpp

@@ -17,3 +17,33 @@ INSTANTIATE_POOL_METHODS(Plan)
 
 Plan *_current_plan = nullptr;
 Plan *_new_plan = nullptr;
+
+void PlanLine::UpdateVisualExtents()
+{
+	if (_network_dedicated) return;
+
+	if (this->tiles.size() < 2) {
+		this->viewport_extents = { INT_MAX, INT_MAX, INT_MAX, INT_MAX };
+		return;
+	}
+
+	int min_x = INT_MAX;
+	int max_x = INT_MIN;
+	int min_y = INT_MAX;
+	int max_y = INT_MIN;
+
+	for (TileIndex t : this->tiles) {
+		const int tile_x = TileX(t);
+		const int tile_y = TileY(t);
+		const int x = tile_y - tile_x;
+		const int y = tile_y + tile_x;
+
+		if (x < min_x) min_x = x;
+		if (x > max_x) max_x = x;
+		if (y < min_y) min_y = y;
+		if (y > max_y) max_y = y;
+	}
+
+	this->viewport_extents = { (int)(min_x * TILE_SIZE * 2 * ZOOM_LVL_BASE), (int)(min_y * TILE_SIZE * ZOOM_LVL_BASE),
+			(int)((max_x + 1) * TILE_SIZE * 2 * ZOOM_LVL_BASE), (int)((max_y + 1) * TILE_SIZE * ZOOM_LVL_BASE) };
+}

src/plans_base.h

@@ -31,6 +31,7 @@ struct PlanLine {
 	bool visible;
 	bool focused;
 	TileVector tiles;
+	Rect viewport_extents;
 
 	PlanLine()
 	{
@@ -153,6 +154,8 @@ struct PlanLine {
 		if (count == 0) return INVALID_TILE;
 		return TileXY(x / count, y / count);
 	}
+
+	void UpdateVisualExtents();
 };
 
 struct Plan : PlanPool::PoolItem<&_plan_pool> {

src/plans_cmd.cpp

@@ -69,6 +69,7 @@ CommandCost CmdAddPlanLine(TileIndex tile, DoCommandFlag flags, uint32 p1, uint3
 			p->lines.pop_back();
 			return CMD_ERROR;
 		}
+		pl->UpdateVisualExtents();
 		if (p->IsListable()) {
 			pl->SetVisibility(p->visible);
 			if (p->visible) pl->MarkDirty();

src/saveload/plans_sl.cpp

@@ -60,6 +60,7 @@ static void Load_PLAN()
 				const size_t tile_count = SlReadUint32();
 				pl->tiles.resize(tile_count);
 				SlArray(&pl->tiles[0], tile_count, SLE_UINT32);
+				pl->UpdateVisualExtents();
 			}
 			p->SetVisibility(false);
 		}
@@ -79,6 +80,7 @@ static void Load_PLANLINE()
 		size_t plsz = SlGetFieldLength() / sizeof(TileIndex);
 		pl->tiles.resize(plsz);
 		SlArray(&pl->tiles[0], plsz, SLE_UINT32);
+		pl->UpdateVisualExtents();
 	}
 
 	for (Plan *p : Plan::Iterate()) {

src/viewport.cpp

@@ -2419,18 +2419,47 @@ void ViewportDrawPlans(const Viewport *vp)
 	DrawPixelInfo *old_dpi = _cur_dpi;
 	_cur_dpi = &_dpi_for_text;
 
+	if (Plan::GetNumItems() != 0) {
+		const Rect bounds = {
+			ScaleByZoom(_dpi_for_text.left - 2, vp->zoom),
+			ScaleByZoom(_dpi_for_text.top - 2, vp->zoom),
+			ScaleByZoom(_dpi_for_text.left + _dpi_for_text.width + 2, vp->zoom),
+			ScaleByZoom(_dpi_for_text.top + _dpi_for_text.height + 2, vp->zoom) + (int)(ZOOM_LVL_BASE * TILE_HEIGHT * _settings_game.construction.max_heightlevel)
+		};
+
+		const int min_coord_delta = bounds.left / (int)(2 * ZOOM_LVL_BASE * TILE_SIZE);
+		const int max_coord_delta = (bounds.right / (int)(2 * ZOOM_LVL_BASE * TILE_SIZE)) + 1;
+
 		for (Plan *p : Plan::Iterate()) {
 			if (!p->IsVisible()) continue;
 			for (PlanLineVector::iterator it = p->lines.begin(); it != p->lines.end(); it++) {
 				PlanLine *pl = *it;
 				if (!pl->visible) continue;
+
+				if (
+					bounds.left   > pl->viewport_extents.right ||
+					bounds.right  < pl->viewport_extents.left ||
+					bounds.top    > pl->viewport_extents.bottom ||
+					bounds.bottom < pl->viewport_extents.top
+				) {
+					continue;
+				}
+
+				TileIndex to_tile = pl->tiles[0];
+				int to_coord_delta = (int)TileY(to_tile) - (int)TileX(to_tile);
 				for (uint i = 1; i < pl->tiles.size(); i++) {
-				const TileIndex from_tile = pl->tiles[i-1];
+					const TileIndex from_tile = to_tile;
+					const int from_coord_delta = to_coord_delta;
+					to_tile = pl->tiles[i];
+					to_coord_delta = (int)TileY(to_tile) - (int)TileX(to_tile);
+
+					if (to_coord_delta < min_coord_delta && from_coord_delta < min_coord_delta) continue;
+					if (to_coord_delta > max_coord_delta && from_coord_delta > max_coord_delta) continue;
+
 					const Point from_pt = RemapCoords2(TileX(from_tile) * TILE_SIZE + TILE_SIZE / 2, TileY(from_tile) * TILE_SIZE + TILE_SIZE / 2);
 					const int from_x = UnScaleByZoom(from_pt.x, vp->zoom);
 					const int from_y = UnScaleByZoom(from_pt.y, vp->zoom);
 
-				const TileIndex to_tile = pl->tiles[i];
 					const Point to_pt = RemapCoords2(TileX(to_tile) * TILE_SIZE + TILE_SIZE / 2, TileY(to_tile) * TILE_SIZE + TILE_SIZE / 2);
 					const int to_x = UnScaleByZoom(to_pt.x, vp->zoom);
 					const int to_y = UnScaleByZoom(to_pt.y, vp->zoom);
@@ -2444,6 +2473,7 @@ void ViewportDrawPlans(const Viewport *vp)
 				}
 			}
 		}
+	}
 
 	if (_current_plan && _current_plan->temp_line->tiles.size() > 1) {
 		for (uint i = 1; i < _current_plan->temp_line->tiles.size(); i++) {