Thread: Creating a new object of a subclass problems.

The initial problem was solved. Please read down to third post for current problem. --TIA

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.

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.

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.

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);
}