OpenGL GLSL - Text rendering query

[Chebmaster]

, or it is somehow getting initialised properly and it can't find the uniform, which is a 2D sampler.

1. It was so NICE of them to declare GLcharARB = Char; PGLcharARB = ^GLcharARB; when Char could be UnicodeChar and OpenGL *only* understands 8-bit strings.

2. It's capricious. Try

glGetUniformLocation(<program>,  PAnsiChar(RawByteString('my_uniform_name'#0)));

3. It can return -1 if your uniform was not used and the GLSL compiler eliminated it.

P.S. I always play it overly safe using wrappers like this one:

class function TGAPI.SafeGetUniformLocation(prog: GLuint; name: RawByteString): GLint;
var
  error: UnicodeString;
begin
  try
    case  Mother^.GAPI.Mode of
     {$ifndef glesonly}
      gapi_GL21,
     {$endif glesonly}
      gapi_GLES2: begin
        Result:= glGetUniformLocation(prog, PAnsiChar(name + #0));
        CheckGLError(true);
      end;
    else
      DieUnsupportedGLMode;
    end;
  except
    Die(RuEn(
      'Не удалось получить расположение постоянной %1 для программы %0',
      'Failed to get uniform %1 location for program %0'
      ), [prog, name]);
  end;
end;

where

procedure CheckGlError(DieAnyway: boolean);
var ec: GLenum;
begin
  {$if defined(cpuarm) and not defined(debug)}
    //Raspberry Pi
    //some shit of a driver spams console with "glGetError 0x500"
    // thus bringing FPS to its knees
    if not DieAnyway then Exit;
  {$endif}

  ec:= glGetError();

  if ec <> 0 then
    if DieAnyway or Mother^.Debug.StopOnOpenGlErrors
      then Die(RuEn(
          'Ошибка OpenGL, %0',
          'OpenGL error, %0'
        ),
        [GlErrorCodeToString(ec)])
      else
        if Mother^.Debug.Verbose then AddLog(RuEn(
            'Ошибка OpenGL, %0',
            'OpenGL error, %0'
          ),
          [GlErrorCodeToString(ec)]);
end;

-- flying over paranoiac's nest