Creating a new object of a subclass problems.

This is a discussion on Creating a new object of a subclass problems. within the C++ Programming forums, part of the General Programming Boards category; The initial problem was solved. Please read down to third post for current problem. --TIA...

  1. #1
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    Undefined referance to Vtable?

    The initial problem was solved. Please read down to third post for current problem. --TIA
    Last edited by Goombaz; 01-08-2006 at 06:59 AM.

  2. #2
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    you can't have a variable name the same name as the class name -- tile is used both as the name of an unsigned int variable in the class constructor and a class.

  3. #3
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    Ok, that was the problem

    However, now something much deeper and more evil seems to be afoot.

    Now it says

    [Linker error] undefined reference to `vtable for visual'

    Oh boy, I have a feeling this isn't something small...

    Code:
    extern HGE * hge;
    /*
      visual.DrawTile
      visual.DrawText
      visual.DrawLine
    
      visual.Draw
    */
    
    class visual
    {
     public:
     // Simple constructor for a new Visual
     visual(float location_z, float location_x,float location_y,unsigned int color)
     {
      this->location_z=location_z;this->location_z=location_x;this->location_z=location_y;this->color=color;
     };
     virtual void render(void);// Base function for Visual render. Will be filled in in subclasses
     static void DrawTile(float,float,float,unsigned int,unsigned int,unsigned char,hgeQuad *);// Make a Tile for this frame
     static void Draw(void);// Run the render in full and purge the list
     protected:
     static visual * root; // Root pointer for rendering list
     visual * next_visual; // Pointer to next visual
     float location_z,location_x,location_y;// XY and Z location for Visual
     unsigned int color; //Color value for Visual 0xAARRGGBB
    };
    visual * visual :: root = 0; // Making sure root pointer is null to begin with
    
    
    class tile : public visual
    {
     public:
     //Constructor for a tile, that passes the needed values to the base class
     tile(float location_z,float location_x,float location_y,unsigned int color,unsigned int tile_number,unsigned char blend,hgeQuad * quad) :
     visual(location_z,location_x,location_y,color)
     {
      this->tile_number = tile_number;
     };
     protected: 
     void render(void);
     unsigned int tile_number;
     unsigned char blend;
     hgeQuad * quad;
    };
    
    //The actual Tile render routine, meant to supplant RenderQuad
    void tile::render(void)
    {
     //Set all the values needed for this specific stamp.
     for(int i=0;i<4;i++)
     {
       quad->v[i].z=1.0;
       quad->v[i].col=color;
     }
     quad->v[0].tx=float(tile_number%39)*32.0/2048.0; quad->v[0].ty=float(tile_number/39)*32.0/2048.0; 
     quad->v[1].tx=float((tile_number%39)+1)*32.0/2048.0; quad->v[1].ty=float(tile_number/39)*32.0/2048.0; 
     quad->v[2].tx=float((tile_number%39)+1)*32.0/2048.0; quad->v[2].ty=float((tile_number/39)+1)*32.0/2048.0; 
     quad->v[3].tx=float(tile_number%39)*32.0/2048.0; quad->v[3].ty=float((tile_number/39)+1)*32.0/2048.0; 
     quad->v[0].x=location_x; quad->v[0].y=location_y;
     quad->v[1].x=location_x+32; quad->v[1].y=location_y;
     quad->v[2].x=location_x+32; quad->v[2].y=location_y+32;
     quad->v[3].x=location_x; quad->v[3].y=location_y+32;
     quad->blend=blend;
     //Send to screen.
     hge->Gfx_RenderQuad(quad);
    }
    
    //Function to create a tile for this frame
    void visual::DrawTile(float location_z,float location_x,float location_y,unsigned int color,unsigned int tile_number,unsigned char blend,hgeQuad * quad)
    {
     visual * newbie = new tile(location_z,location_x,location_y,color,tile_number,blend,quad);
    } 
    
    //Renderquad test function for member function used for Tiles
    void RenderQuad(float x, float y, unsigned int tile, unsigned int color, unsigned char blend,hgeQuad * quad,HGE* hge)
    {
     //Set all the values needed for this specific stamp.
     for(int i=0;i<4;i++)
     {
       quad->v[i].z=1.0;
       quad->v[i].col=color;
     }
     quad->v[0].tx=float(tile%39)*32.0/2048.0; quad->v[0].ty=float(tile/39)*32.0/2048.0; 
     quad->v[1].tx=float((tile%39)+1)*32.0/2048.0; quad->v[1].ty=float(tile/39)*32.0/2048.0; 
     quad->v[2].tx=float((tile%39)+1)*32.0/2048.0; quad->v[2].ty=float((tile/39)+1)*32.0/2048.0; 
     quad->v[3].tx=float(tile%39)*32.0/2048.0; quad->v[3].ty=float((tile/39)+1)*32.0/2048.0; 
     quad->v[0].x=x; quad->v[0].y=y;
     quad->v[1].x=x+32; quad->v[1].y=y;
     quad->v[2].x=x+32; quad->v[2].y=y+32;
     quad->v[3].x=x; quad->v[3].y=y+32;
     quad->blend=blend;
     //Send to screen.
     hge->Gfx_RenderQuad(quad);
    }
    Attempting to create the object and assign it to a pointer via New is the line that causes the linker to give me the error.
    Last edited by Goombaz; 01-08-2006 at 07:00 AM.

  4. #4
    ZuK
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    The compiler is looking for the implementation of visual::render()
    Try this way:
    Code:
    virtual void render(void) = 0;// Base function for Visual render. Will be filled in in subclasses
    or that
    Code:
    virtual void render(void){};// Base function for Visual render. Will be filled in in subclasses
    Kurt

    Edit: there might be more errors but I'm not able to read code without indentation.
    Last edited by ZuK; 01-08-2006 at 07:29 AM.

  5. #5
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    Ah man, thanks guys. I really appreciate the help.

    Sometimes it's so hard to find your own errors, especially as you are learning. That fixed it right up. In fact, I remember reading to do that exact thing.

    Sorry about the indentations etc. I am sure there are more errors, I will improve the style to make future posts more tolerable.
    Last edited by Goombaz; 01-08-2006 at 07:35 AM.

  6. #6
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    By the way, how much of a readability improvement is this?

    There are funky spaces appearing in the code when I paste it here.

    Code:
    //HGE engine instance pointer
    extern HGE * hge;
    /*
    ** The visual class is an abstract base class for all
    ** objects representing actual screen drawing.
    ** 
    **
    */
    //==============================================================================
    //= Visual Base Class                                                          =
    //==============================================================================
    class visual
    {
          public://*****************************************************************
          // Make a Tile
          static void DrawTile(float,float,float,unsigned int,unsigned int,unsigned char,hgeQuad *);
          // Draw all visuals
          static void Draw(void);
          //Constructor for visual
          visual(float location_z, float location_x,float location_y,unsigned int color)
          {
                       this->location_z=location_z;this->location_z=location_x;
                       this->location_z=location_y;this->color=color;
                       this->next_visual = 0;
          };
          // Base virtual function for rendering objects
          virtual void render(void){};
          protected://**************************************************************
          // XY and Z location for Visual
          float location_z,location_x,location_y;
          //Color value for Visual 0xAARRGGBB
          unsigned int color; 
          // Root pointer for rendering list
          static visual * root; 
          // Pointer to next visual
          visual * next_visual; 
    };
    // Making sure root pointer is null to begin with
    visual * visual :: root = 0; 
    //==============================================================================
    //= tile subclass of visual : Represents a textured tile on screen             =
    //==============================================================================
    class tile : public visual
    {
          public://*****************************************************************
          //Constructor for tile
          tile(float location_z,float location_x,float location_y,unsigned int color,unsigned int tile_number,unsigned char blend,hgeQuad * quad) :
          visual(location_z,location_x,location_y,color)
          {
                 this->tile_number = tile_number;
                 this->quad = quad;
                 this->blend = blend;
          };
          //Render function for tile
          void render(void);
          protected://************************************************************** 
          //Which of the tiles in the set will be used
          unsigned int tile_number;
          //Which style of blending will be used
          unsigned char blend;
          //Which quad will be used to stamp
          hgeQuad * quad;
    };
    //Function to create a tile for this frame
    void visual::DrawTile(float location_z,float location_x,float location_y,unsigned int color,unsigned int tile_number,unsigned char blend,hgeQuad * quad)
    {
         //Create a tile object and give to new_tile pointer
         visual * new_tile = new tile(location_z,location_x,location_y,color,tile_number,blend,quad);
         //If root is null root points to this tile and it points to null
         if(root = 0)
         {
                 root = new_tile;
                 new_tile->next_visual=0;
         }
         //Otherwise it will have to be placed in order
         else
         {
                 // ADD CODE HERE for: Placing in ordered list
         };
    } 
    //The tile specific render routine
    void tile::render(void)
    {
         //Set all the values needed for this specific stamp.
         for(int i=0;i<4;i++)
         {
                 //I don't use internal Z so I just set it to 1 for all verts.
                 quad->v[i].z=1.0;
                 //I don't need individually shaded verts so I set all to color value.
                 quad->v[i].col=color;
         }
         //Sets the texture location to use via tile from root image.
         quad->v[0].tx=float(tile_number%39)*32.0/2048.0; quad->v[0].ty=float(tile_number/39)*32.0/2048.0; 
         quad->v[1].tx=float((tile_number%39)+1)*32.0/2048.0; quad->v[1].ty=float(tile_number/39)*32.0/2048.0; 
         quad->v[2].tx=float((tile_number%39)+1)*32.0/2048.0; quad->v[2].ty=float((tile_number/39)+1)*32.0/2048.0; 
         quad->v[3].tx=float(tile_number%39)*32.0/2048.0; quad->v[3].ty=float((tile_number/39)+1)*32.0/2048.0; 
         //Sets quads according to screen location desired.
         quad->v[0].x=location_x; quad->v[0].y=location_y;
         quad->v[1].x=location_x+32; quad->v[1].y=location_y;
         quad->v[2].x=location_x+32; quad->v[2].y=location_y+32;
         quad->v[3].x=location_x; quad->v[3].y=location_y+32;
         quad->blend=blend;
         //Send to screen.
         hge->Gfx_RenderQuad(quad);
    }
    Last edited by Goombaz; 01-08-2006 at 08:33 AM.

  7. #7
    ZuK
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    This is a lot better.
    You should just add a few blank lines ( hope you haven't only to save space in the forum )
    Kurt

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