Polygons not visible

[John Ioannides]

Hello,

I have some old code to create and display GLPolygons that worked ok, however I just upgraded to Rio and installed the latest GLScene version and the same code does not seem to work (I attached the output of my app as it works complied with previous version of GLScene and with the latest 1.8)

poly := TGLPolygon.Create(glscene1);
// add nodes ///
..........................
poly.Division := 100;
poly.VisibilityCulling := vcObjectBased;
poly.Parts := [pptop];
poly.Material.BlendingMode := bmOpaque;
poly.Material.FrontProperties.Ambient.AsWinColor := clblack;
poly.Material.FrontProperties.Diffuse.AsWinColor := SomeColor
poly.Material.FrontProperties.Diffuse.Alpha := 0.8;//0.80;
poly.Material.PolygonMode := pmFill;
poly.Material.BackProperties.Diffuse.AsWinColor := foo^.Color;
poly.Material.BackProperties.Diffuse.Alpha := 0.30;//0.30;
poly.Material.BackProperties.Ambient.AsWinColor := clblack;

Can anyone please suggest what I should change in order to make the polygons visible?

Regards

[Jerome.D (BeanzMaster)]

Hi John can you upload a simple demo for testing please, it will be more easy for me to track the problem et answer to you and i'll can made change in code if needed.

Regards

[John Ioannides]

Hello,

Thank you for your swift reply! Please find attached a simple project but I am not sure the plane coordinates are ok. However I would expect to see something :)

Regards

[Jerome.D (BeanzMaster)]

Hum, It's weird because with Delphi RIO 10.3 Community Edition and the latest version of GLScene 1.8 ,with your sample all seems good (See screenshot)

What your Graphic Card model ?
Check and update the GPU driver

[Jerome.D (BeanzMaster)]

Hum,

First you don't need to pass GLScene1 as parameter in surface_plane := TGLPlane.Create(GLScene1); try to just do" surface_plane := TGLPlane.Create(nil);" because after you add it in DummyCube with" GLDummyCube.AddChild(surface_plane);"
An other way is directly to do " surface_plane := TGLPlane.CreateAsChild(GLDummyCube);"

So perhaps in your original application the order of your objects are not good and if you use DummyCube as parent check visibility and Culling properties

I see, also if you use DirectOpenGL between 2 be careful to restore the openGL's States correctly after the rendering

Cheers

[John Ioannides]

Hello, I am afraid I do not know what to check exactly, I wrote that code many years ago and until recently with GLScene 1.5 it was working ok. Would it be possible for you to modify my project to draw a simple polygon so that I can see the changes you mentioned?

Thank you very much for your time and effort.

Regards

[John Ioannides]

Hello,

I changed the PolygonMode from fill to lines and the result I get is not what I was expecting, maybe something changed to the way a polyline should be defined?

Regards

[Jerome.D (BeanzMaster)]

Hi, like i said your little sample work perfectly on my PC without change your code.
Can you upload your whole project for can i'll test ?

What is your GPU Card ?

Regards

[John Ioannides]

Hello,

If you check the screenshot you sent me you will see that only the 2 planes are visible, the polyline is not, that is the part that is not working. My guess is that I will have to remove the polyline and replace it with a plane or switch back to 1.5

Thank you very much for your time and effort, I really do appreciate it!

Regards

[Jerome.D (BeanzMaster)]

Hi Ok i don't understand

Try to set PolygonMode to pmLines

[Jerome.D (BeanzMaster)]

Check and run \GLScene\Samples\Delphi\Demos\collisions\TriangleBox tell if it work and if you see the triangle polygon.

[John Ioannides]

Hello,

I checked the demo, the triangle polygon (GLPolygon1) is not visible, only the lines are plotted (GLLines2), if you comment out lines 137 to 140 then only the points appear.

[Andrzej Karwowski]

I have similar problem with Delphi 10.2 and GLScene. When I choose Win32 as target platform (which I prefer) polygons are not visible. If I change target to Win64 all polygons appear.

[John Ioannides]

I had to roll back to 1.5 to solve this issue but it would be nice to have this issue fixed in the latest version.

[Andrzej Karwowski]

Thank you for the information, perhaps I will do the same. I hope that the GLScene team will fix it.

[Pavel Vassiliev]

John,
It's a weird behaviour for polygon's drawing with ok on win64 and empty in win32. The reason not found yet.
PW

[Pavel Vassiliev]

John,
Maybe the reason is rooted in changing some dynamic methods to virtual or declaring inlines, I really don't guess what's the matter now. Will search later.
PW

[Reinier Sterkenburg]

I have the same problem and solution: on win32 polygons don't show up, but on win64 they do..

[Niels Bach-Sørensen]

I have this issue as well. Does anyone have an approximate timeframe for a fix?

[Filippo Forlani]

I have the same problem with different PC delphi 10.1

[Egroc]

Same problem here. I cannot view TGLPolygon on Win32. If compile Win64 TGLPolygon shows but no transparency/blend affected, only solid TGLPolygon...

Issue is in versión 1.6 and up. 1.5 Works OK. Tested on delphi XE7 and 10.3, both fails. Tested on various Nvidia Geforce cards, all failed.

Any solution for this problem?

[Marco Farina]

I have the same problem (Delphi XE 10.3 Rio): polygons shows correctly when compiling Win64, but nothing Win32. Just downloaded the latest version of OpenGL but nothing changed. Any suggestion?

[LefjuCabro]

Hi,
Do you have any suggestion about resolving this ? Is there any modifications that we could apply in source ?
I cannot compile my app to Win64.
Regards

[bobmc]

Same problem here, TGLPolygons don't show in 32bits, only in 64bits.

[Jerome.D (BeanzMaster)]

Hi to all , this problem seems to be an kind of range overflow so
the only problem i see it's in the code of polygon itself or in vectors's formula

I don't have Delphi, only Lazarus. But with Lazarus the "\GLScene\Samples\Delphi\Demos\collisions\TriangleBox " work perfectly by compiling it in Win32 and Win64

In the Lazarus's code
In GLGeomObject unit we have

procedure TGLPolygon.BuildList(var rci: TGLRenderContextInfo);
var
  Normal: TAffineVector;
  pNorm: PAffineVector;
begin
  if (Nodes.Count > 1) then
  begin
    Normal := Nodes.Normal;
    if VectorIsNull(Normal) then
      pNorm := nil
    else
      pNorm := @Normal;
    if ppTop in FParts then
    begin
      if SplineMode = lsmLines then
        Nodes.RenderTesselatedPolygon(true, pNorm, 1)
      else
        Nodes.RenderTesselatedPolygon(true, pNorm, Division);
    end;
    // tessellate bottom polygon
    if ppBottom in FParts then
    begin
      if Assigned(pNorm) then
        NegateVector(Normal);
      if SplineMode = lsmLines then
        Nodes.RenderTesselatedPolygon(true, pNorm, 1, true)
      else
        Nodes.RenderTesselatedPolygon(true, pNorm, Division, true);
    end;
  end;
end;  

in GLNodes.pas

procedure TGLNodes.RenderTesselatedPolygon(ATextured: Boolean;
  ANormal: PAffineVector = nil; ASplineDivisions: Integer = 1;
  AInvertNormals: Boolean = False);
var
  I: Integer;
  Tess: PGLUTesselator;
  DblVector: TAffineDblVector;
  Spline: TCubicSpline;
  SplinePos: PAffineVector;
  F: Single;

begin
  if Count > 2 then
  begin
    // Create and initialize the GLU tesselator
    Tess := GluNewTess;
    GluTessCallback(Tess, GLU_TESS_BEGIN, @GL.Begin_);
    if ATextured then
      GluTessCallback(Tess, GLU_TESS_VERTEX, @TessIssueVertex)
    else
      GluTessCallback(Tess, GLU_TESS_VERTEX, @GL.Vertex3fv);
    GluTessCallback(Tess, GLU_TESS_END, @GL.End_);
    GluTessCallback(Tess, GLU_TESS_ERROR, @TessError);
    GluTessCallback(Tess, GLU_TESS_COMBINE, @TessCombine);
    NbExtraVertices := 0;
    // Issue normal
    if Assigned(ANormal) then
    begin
      GL.Normal3fv(PGLFloat(ANormal));
      GluTessNormal(Tess, ANormal^.V[0], ANormal^.V[1], ANormal^.V[2]);
    end;
    // Issue polygon
    GluTessBeginPolygon(Tess, nil);
    GluTessBeginContour(Tess);
    if ASplineDivisions <= 1 then
    begin
      // no spline, use direct coordinates
      GetMem(NewVertices, Count * SizeOf(TAffineVector));
      if AInvertNormals then
      begin
        for I := Count - 1 downto 0 do
        begin
          SetVector(DblVector, PAffineVector(Items[I].AsAddress)^);
          GluTessVertex(Tess, DblVector, Items[I].AsAddress);
        end;
      end
      else
      begin
        for I := 0 to Count - 1 do
        begin
          SetVector(DblVector, PAffineVector(Items[I].AsAddress)^);
          GluTessVertex(Tess, DblVector, Items[I].AsAddress);
        end;
      end;
    end
    else
    begin
      // cubic spline
      GetMem(NewVertices, 2 * ASplineDivisions * Count * SizeOf(TAffineVector));
      Spline := CreateNewCubicSpline;
      F := 1.0 / ASplineDivisions;
      if AInvertNormals then
      begin
        for I := ASplineDivisions * (Count - 1) downto 0 do
        begin
          SplinePos := AllocNewVertex;
          Spline.SplineAffineVector(I * F, SplinePos^);
          SetVector(DblVector, SplinePos^);
          GluTessVertex(Tess, DblVector, SplinePos);
        end;
      end
      else
      begin
        for I := 0 to ASplineDivisions * (Count - 1) do
        begin
          SplinePos := AllocNewVertex;
          Spline.SplineAffineVector(I * F, SplinePos^);
          SetVector(DblVector, SplinePos^);
          GluTessVertex(Tess, DblVector, SplinePos);
        end;
      end;
      Spline.Free;
    end;
    GluTessEndContour(Tess);
    GluTessEndPolygon(Tess);
    // release stuff
    if Assigned(NewVertices) then
      FreeMem(NewVertices);
    GluDeleteTess(Tess);
  end;
end; 

In GLVectorGeometry. pas

procedure NegateVector(var v : TAffineVector);
// EAX contains address of v
{$ifndef GEOMETRY_NO_ASM}
asm
      FLD DWORD PTR [EAX]
      FCHS
      FSTP DWORD PTR [EAX]
      FLD DWORD PTR [EAX+4]
      FCHS
      FSTP DWORD PTR [EAX+4]
      FLD DWORD PTR [EAX+8]
      FCHS
      FSTP DWORD PTR [EAX+8]
{$else}
begin
   v.V[0]:=-v.V[0];
   v.V[1]:=-v.V[1];
   v.V[2]:=-v.V[2];
{$endif}
end;  

So in first try to disable ASM by activate GEOMETRY_NO_ASM and GLS_NO_ASM in GLScene.inc like this

// De-Activate assembly routines in GLVectorGeometry.pas
{$DEFINE GEOMETRY_NO_ASM} 

// De-Activate assembly routines in other GLS units.
{$DEFINE GLS_NO_ASM}  

You can also try to enabled those options to help tracking bugs

// Activate Logging
{$DEFINE GLS_LOGGING}

// Activate OpenGL debug mode
{$DEFINE GLS_OPENGL_DEBUG} 

And if someone can diff those code below, it will be help

Cheers