⚡️ Speed up preview rendering

Client/ULandscape.pas

@@ -322,6 +322,19 @@ type
 
   TGhostTile = class(TStaticItem);
 
+  { TMovableGhostTile }
+
+  TMovableGhostTile = class(TGhostTile)
+  private
+    FOriginalX: Word;
+    FOriginalY: Word;
+    FOriginalZ: ShortInt;
+  public
+    property OriginalX: Word read FOriginalX write FOriginalX;
+    property OriginalY: Word read FOriginalY write FOriginalY;
+    property OriginalZ: ShortInt read FOriginalZ write FOriginalZ;
+  end;
+
 operator enumerator(AScreenBuffer: TScreenBuffer): TScreenBufferItemEnumerator;
 
 implementation

Client/UfrmMain.pas

@@ -368,6 +368,7 @@ type
     FUoaDesigns: TUoaDesigns;
     FCurrentUoaDesign: TUoaDesign;
     FCurrentUoaDesignAnchor: TWorldItem;
+    FCurrentUoaTiles: TStaticItemList;
     { Methods }
     procedure BuildTileList;
     function  ConfirmAction: Boolean;
@@ -383,6 +384,7 @@ type
     procedure LoadRandomPresets;
     procedure LoadUoaDesigns;
     procedure MoveBy(AOffsetX, AOffsetY: Integer); inline;
+    procedure MoveUoaDesign(AX, AY: Word; AZ: ShortInt);
     procedure PlaceUoaDesign(AWorldItem: TWorldItem);
     procedure PrepareMapCell(AMapCell: TMapCell);
     procedure PrepareScreenBlock(ABlockInfo: PBlockInfo);
@@ -2006,6 +2008,8 @@ end;
 procedure TfrmMain.vstUoaDesignsDblClick(Sender: TObject);
 var
   selectedNode: PVirtualNode;
+  designTile: TStaticItem;
+  virtualTile: TMovableGhostTile;
 begin
   // Make sure to reset the current view first.
   PreviewUoaDesign(nil);
@@ -2020,7 +2024,25 @@ begin
     Exit;
 
   FreeAndNil(FCurrentUoaDesign);
+  FreeAndNil(FCurrentUoaTiles);
   FCurrentUoaDesign := FUoaDesigns.LoadDesign(FUoaDesigns.Headers[selectedNode^.Index]);
+  FCurrentUoaTiles := TStaticItemList.Create(False);
+
+  for designTile in FCurrentUoaDesign.Tiles do
+  begin
+    virtualTile := TMovableGhostTile.Create(nil, nil, 0, 0);
+    virtualTile.X := designTile.X;
+    virtualTile.Y := designTile.Y;
+    virtualTile.Z := designTile.Z;
+    virtualTile.OriginalX := designTile.X;
+    virtualTile.OriginalY := designTile.Y;
+    virtualTile.OriginalZ := designTile.Z;
+    virtualTile.TileID := designTile.TileID;
+    virtualTile.Hue := designTile.Hue;
+    FCurrentUoaTiles.Add(virtualTile);
+    FVirtualTiles.Add(virtualTile);
+  end;
+  MoveUoaDesign(FX, FY, FLandscape.GetLandAlt(FX, FY, 0));
 
   RegisterSelectionListener(@PlaceUoaDesign);
   RegisterHoverListener(@PreviewUoaDesign);
@@ -2328,6 +2350,39 @@ begin
   UpdateCurrentTile;
 end;
 
+procedure TfrmMain.MoveUoaDesign(AX, AY: Word; AZ: ShortInt);
+var
+  offsetX, offsetY, offsetZ, maxZ: Integer;
+  item: TStaticItem;
+begin
+  maxZ := Low(Integer);
+  for item in FCurrentUoaDesign.Tiles do
+    if item.Z > maxZ then
+      maxZ := item.Z;
+
+  offsetX := AX - FCurrentUoaDesign.Header.Width div 2;
+  offsetY := AY - FCurrentUoaDesign.Header.Height div 2;
+  offsetZ := EnsureRange(AZ, -128, 127);
+
+  if offsetX < 0 then offsetX := 0;
+  if offsetX + FCurrentUoaDesign.Header.Width > FLandscape.CellWidth then
+    offsetX := FLandscape.CellWidth - FCurrentUoaDesign.Header.Width;
+  if offsetY < 0 then offsetY := 0;
+  if offsetY + FCurrentUoaDesign.Header.Height > FLandscape.CellHeight then
+    offsetY := FLandscape.CellHeight - FCurrentUoaDesign.Header.Height;
+  if offsetZ + maxZ > 127 then
+    offsetZ := 127 - maxZ;
+
+  for item in FCurrentUoaTiles do
+  begin
+    item.X := TMovableGhostTile(item).OriginalX + offsetX;
+    item.Y := TMovableGhostTile(item).OriginalY + offsetY;
+    item.Z := TMovableGhostTile(item).OriginalZ + offsetZ;
+  end;
+
+  InvalidateScreenBuffer;
+end;
+
 procedure TfrmMain.PlaceUoaDesign(AWorldItem: TWorldItem);
 var
   selectedNode: PVirtualNode;
@@ -2338,6 +2393,7 @@ begin
   UnregisterSelectionListener(@PlaceUoaDesign);
   UnregisterHoverListener(@PreviewUoaDesign);
   FreeAndNil(FCurrentUoaDesign);
+  FreeAndNil(FCurrentUoaTiles);
   FCurrentUoaDesignAnchor := nil;
   vstUoaDesigns.Enabled := True;
   btnCancelUOAPlacement.Visible := False;
@@ -2637,59 +2693,20 @@ begin
 end;
 
 procedure TfrmMain.PreviewUoaDesign(AWorldItem: TWorldItem);
-var
-  offsetX, offsetY, offsetZ: Integer;
-  newX, newY, newZ: Integer;
-  i: Integer;
-  designTile, virtualTile: TStaticItem;
-  blockInfo: PBlockInfo;
 begin
   // If nothing has changed, we can keep this short.
   if FCurrentUoaDesignAnchor = AWorldItem then
     Exit;
+  FCurrentUoaDesignAnchor := AWorldItem;
 
   // No design selected? Well then.
   if FCurrentUoaDesign = nil then
     Exit;
 
-  for i := FVirtualTiles.Count - 1 downto 0 do
-  begin
-    if FVirtualTiles[i] is TGhostTile then
-    begin
-      FScreenBuffer.Delete(FVirtualTiles[i]);
-      FVirtualTiles.Delete(i);
-    end;
-  end;
-
   if AWorldItem = nil then
     Exit;
 
-  offsetX := AWorldItem.X - FCurrentUoaDesign.Header.Width div 2;
+  MoveUoaDesign(AWorldItem.X, AWorldItem.Y, AWorldItem.Z);
-  offsetY := AWorldItem.Y - FCurrentUoaDesign.Header.Height div 2;
-  offsetZ := AWorldItem.Z;
-
-  for designTile in FCurrentUoaDesign.Tiles do
-  begin
-    newX := designTile.X + offsetX;
-    newY := designTile.Y + offsetY;
-    newZ := designTile.Z + offsetZ;
-
-    if (newX < 0) or (newX >= FLandscape.CellWidth) or
-      (newY < 0) or (newY >= FLandscape.CellHeight) or
-      (newZ < -128) or (newZ > 127) then
-      // We can't render this tile. Skip it.
-      continue;
-
-    virtualTile := TGhostTile.Create(nil, nil, 0, 0);
-    virtualTile.X := newX;
-    virtualTile.Y := newY;
-    virtualTile.Z := newZ;
-    virtualTile.TileID := designTile.TileID;
-    virtualTile.Hue := designTile.Hue;
-    FVirtualTiles.Add(virtualTile);
-  end;
-
-  InvalidateScreenBuffer;
 end;
 
 procedure TfrmMain.Render;
@@ -3406,7 +3423,9 @@ begin
 
   // If the current tile is nil, but we still have a selected tile, the
   // procedure is pointless - the selection should stay intact.
-  if (CurrentTile <> nil) or (SelectedTile = nil) then
+  // Same if we are currently placing a UOA design, since we reuse the virtual
+  // tile and just update its position.
+  if ((CurrentTile <> nil) or (SelectedTile = nil)) and (FCurrentUoaTiles = nil) then
   begin
     if CurrentTile = nil then
       selectedRect := Rect(-1, -1, -1, -1)