TFGIndexTexCoordList.Reverse doesn't reverse TExCoords

[Alexandre Guilleme]

All is in the title !
The vertices indexes are reversed, but the texcoords are not.
Here's a patch to fix it

Index: GLVectorFileObjects.pas
===================================================================
--- GLVectorFileObjects.pas (révision 6451)
+++ GLVectorFileObjects.pas (copie de travail)
@@ -1249,6 +1249,7 @@
     procedure WriteToFiler(writer: TVirtualWriter); override;
     procedure ReadFromFiler(reader: TVirtualReader); override;

+    procedure Reverse; override;
     procedure BuildList(var mrci: TRenderContextInfo); override;
     procedure AddToTriangles(aList: TAffineVectorList;
       aTexCoords: TAffineVectorList = nil;
@@ -6984,6 +6985,16 @@
   FTexCoords.Assign(val);
 end;

+// Reverse
+//
+
+procedure TFGIndexTexCoordList.Reverse;
+begin
+  inherited;
+
+  TexCoords.Reverse;
+end;
+
 // BuildList
 //

[Alexandre Guilleme]

Maybe this function should be more "intelligent" than juste reversing lists.
if the Mode of TFGVertexIndexList (TFGIndexTexCoordList's parent) is fgmmTriangleFan, this Reverse function is not correct if the goal is to see the mesh from the other side.

In this mode, the first vertex is common to all triangles. If the list is just reversed, this vertex is swapped with the last one, which becomes the common one.
I think the Reverse function should contain a piece of code like this :

  VertexIndices.Reverse; // <- existing code
  if (Self.Mode = fgmmTriangleFan) and (VertexIndices.Count > 0) then
    VertexIndices.Move(VertexIndices.Count-1, 0); //Put the first vertex back to its place

and so on for the TexCoords in TFGIndexTexCoordList

PS: This change will not work until the Move function bug is fixed

[Alexandre Guilleme]

The reverse function doesn't work anymore in fgmmTriangleStrip with an even number of vertices (the normal keeps the same direction).

Here is a new version of the patch (also in attachment)

Index: Source/GLVectorFileObjects.pas
===================================================================
--- Source/GLVectorFileObjects.pas  (révision 6451)
+++ Source/GLVectorFileObjects.pas  (copie de travail)
@@ -1162,6 +1162,7 @@
     procedure AddToList(source, destination: TAffineVectorList;
       indices: TIntegerList);

+    procedure ReverseListByMode(AList: TBaseList);
   public
     { Public Declarations }
     constructor Create; override;
@@ -1253,6 +1254,7 @@
     procedure AddToTriangles(aList: TAffineVectorList;
       aTexCoords: TAffineVectorList = nil;
       aNormals: TAffineVectorList = nil); override;
+    procedure Reverse; override;

     procedure Add(idx: Integer; const texCoord: TAffineVector); overload;
     procedure Add(idx: Integer; const s, t: Single); overload;
@@ -6529,6 +6531,34 @@
   InvalidateVBO;
 end;

+// ReverseListByMode
+//
+
+procedure TFGVertexIndexList.ReverseListByMode(AList: TBaseList);
+begin
+  if AList.Count = 0 then
+    Exit; //<<<<<<<<<< Exit >>>>>>>>>>
+
+  case Mode of
+    fgmmTriangleFan : begin
+      //0-1-2-3-4-5 => 0-5-4-3-2-1
+      AList.Reverse;
+      AList.Move(AList.Count-1, 0);
+    end;
+    fgmmTriangleStrip : begin
+      //0-1-2-3-4-5 => 0-0-1-2-3-4-5 (duplicating 1st vertex inverts normal)
+      AList.InsertNulls(0, 1);
+      AList.Copy(1, 0);
+    end;
+    fgmmTriangles, fgmmFlatTriangles, fgmmQuads : begin
+      //0-1-2-3-4-5 => 5-4-3-2-1-0
+      AList.Reverse;
+    end;
+  else
+    Assert(False);
+  end;
+end;
+
 // BuildList
 //

@@ -6676,7 +6706,7 @@

 procedure TFGVertexIndexList.Reverse;
 begin
-  VertexIndices.Reverse;
+  ReverseListByMode(VertexIndices);
   InvalidateVBO;
 end;

@@ -6984,6 +7014,16 @@
   FTexCoords.Assign(val);
 end;

+// Reverse
+//
+
+procedure TFGIndexTexCoordList.Reverse;
+begin
+  inherited;
+
+  ReverseListByMode(TexCoords);
+end;
+
 // BuildList
 //

Index: Source/VectorLists.pas
===================================================================
--- Source/VectorLists.pas  (révision 6451)
+++ Source/VectorLists.pas  (copie de travail)
@@ -134,6 +134,7 @@
     procedure DeleteItems(Index: Integer; nbVals: Cardinal);
     procedure Exchange(index1, index2: Integer);
     procedure Move(curIndex, newIndex: Integer);
+    procedure Copy(srcIndex, dstIndex: Integer);
     procedure Reverse;

         {: Nb of items in the list.<p>
@@ -1214,6 +1215,22 @@
   end;
 end;

+// Copy
+//
+procedure TBaseList.Copy(srcIndex, dstIndex: Integer);
+begin
+   if srcIndex<>dstIndex then begin
+{$IFOPT R+}
+    Assert(Cardinal(srcIndex)<Cardinal(Count));
+    Assert(Cardinal(dstIndex)<Cardinal(Count));
+{$ENDIF}
+    if FItemSize=4 then
+       PInteger(@FBaseList[dstIndex*FItemSize])^ := PInteger(@FBaseList[srcIndex*FItemSize])^
+    else
+      System.Move(FBaseList[srcIndex*FItemSize], FBaseList[dstIndex*FItemSize], FItemSize);
+  end;
+end;
+
 // Reverse
 //
 procedure TBaseList.Reverse;