Thread: Multiple include problem

Before you start in and say use this:

Code:

#ifndef FOO
#define FOO
..
#endif

I already have.

Problem:
I'm rendering a terrain scene with water that reflects the scene around it. All vectors for the water point straight up and the eventual plan is to use the Fresnel term in a shader to perturb the water. In order to do this correctly I must use cubic environment mapping. The basic idea of cubic environment mapping is that you draw the scene from 6 different directions with the camera at the center of the scene. Each view matrix represents a 90 degree field of view. You render this to a texture and then use that texture for the primtive that is supposed to reflect the geometry. But the catch is you cannot render the object that is doing the reflecting in the cube map render.

In order to do this in my system, the CWater object requires a pointer to the CTerrainApp class which is derived from CD3DApp which is the core engine code. The message loop of CD3DApp calls the pure virtual function ScreenRender. ScreenRender is then defined to call CoreRender with bRenderWater set to true. Inside of Water::Render(), if water reflections are enabled, then I call CWater::RenderCubeMap(). Inside of RenderCubeMap() I must call CTerrainApp::CoreRender with bRenderWater set to false.

So as you see CWater must include CTerrainApp.h and CTerrainApp.h must include CWater.h. MSVC .NET is telling me that CTerrainApp is an undefined identifier and thus spits out several more errors pointing to the fact that it does not know what CTerrainApp is in CWater file scope. Even though I'm including CTerrainApp.h, it is not including the file.

How do I fix this? I must call the render for the core engine in order to render the scene to the cube map texture, but it won't allow me to pass a pointer to it because it says it's undefined.

Quite odd.

Code:

#include "CD3DApp.h"
#include "CCamera.h"        //Camera
#include "CTerrain.h"       //Terrain
//#include "CSky.h"           //Sky plane
#include "CWater.h"         //Water plane w/ cubic environ mapping
//#include "CSun.h"           //Sun billboard
#include "CFrustrum.h"      //Frustum
#include "CSkyBox.h"        //Skybox

//For fonts
#include "dxutil.h"
#include "d3dutil.h"
#include "d3dfont.h"

class CTerrainApp:public CD3DApp
{
  CCamera          *TheCamera;
...
...

Code:

#ifndef CWATER
#define CWATER

#include "d3dx9.h"
#include "dxutil.h"
#include "d3dutil.h"

#include "CTerrainApp.h"


struct WaterVertex
{
  D3DXVECTOR3 Pos;
  D3DXVECTOR3 Normal;
  D3DCOLOR    Color;
  float u1,v1;
  float u2,v2;
    
  static const DWORD FVF;

  WaterVertex(void):Pos(D3DXVECTOR3(0.0f,0.0f,0.0f)),Color(0),
                Normal(D3DXVECTOR3(0.0f,0.0f,0.0f)),
                u1(0.0f),v1(0.0f),u2(0.0f),v2(0.0f) {}
  
  WaterVertex(D3DXVECTOR3 _Pos,float _u,float _v):Pos(_Pos),u1(_u),v1(_v) {}
  WaterVertex(float x,float y,float z,float u,float v):
              Pos(D3DXVECTOR3(x,y,z)),u1(u),v1(v) {}

};



class CWater
{
  IDirect3DDevice9       *m_pDevice;
  IDirect3DCubeTexture9  *m_pCubeMap;
  WaterVertex             Vertices[4];
  CTerrainApp             *m_pApp;
...

Results:

d:\msvc .net 05\terrain -.net 05\cwater.h(38) : error C2143: syntax error : missing ';' before '*'
d:\msvc .net 05\terrain -.net 05\cwater.h(38) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
d:\msvc .net 05\terrain -.net 05\cwater.h(38) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
d:\msvc .net 05\terrain -.net 05\cwater.h(51) : error C2061: syntax error : identifier 'CTerrainApp'

d:\msvc .net 05\terrain -.net 05\cterrainapp.h(32) : error C2143: syntax error : missing ';' before '*'
d:\msvc .net 05\terrain -.net 05\cterrainapp.h(32) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
d:\msvc .net 05\terrain -.net 05\cterrainapp.h(32) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

> #ifndef FOO
> #define FOO
But have you checked for uniqueness.
If something else accicentally defines the same symbol, then your file won't be included because it thinks it already has been included.

I don't know about your compiler, but gcc has this handy option to stop after the pre-processor step.
g++ -E prog.cpp
Produces prog.i, which is the output of the pre-processor, that is all the #includes and #defines have been expanded (.i files are very long if you have lots of includes). If you have such a feature, try to see if the expected include is actually happening.

Also, if all you need is the class name (as a pointer), then a test of
// #include "CTerrainApp.h"
class CTerrainApp;

Should at least make it compile, if it's just a visibility problem.

does a forward reference have any effect?

Thanks Magos that fixed it. Kind of feels like a hack but I guess there isn't any other way. I really thought that the #ifndef #define #endif mechanism solved this issue, but I guess it doesn't.

Any other standard way to do this?

You use Visual Studio right?
Does using '#pragma once' make a difference?

Dunno. Haven't tried it yet.

I'm using VS .NET 05 Express for now and was using MSVC 6.

Well it appears to be a flaw in my design but I don't know any other way to do it. In order for RenderCubeMap() to actually re-render the scene from 6 different views it must call CTerrainApp::CoreRender(). The only other way would be to delegate the water cube map render to the app class which doesn't seem quite the way to go.

Do you manually render the scene from 6 different views or do you let DX do the work? I know OpenGL has cube mapping support, I'd imagine DX does too.