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tcsavage

'LPSTR' to 'LPCWSTR'

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Recently I have been following the tutorials at directxtutorial.com and so far they have been great. Unfortunately, I have hit a major snag and over the last few days I have been crawling the internet trying to find a solution which I havn't yet. This issue lies with the D3DXCreateTextureFromFile() function in init_graphics(). Here is the whole code as it is right now:
// include the basic windows header files and the Direct3D header file
#include <windows.h>
#include <windowsx.h>
#include <d3d9.h>
#include <d3dx9.h>

// define the screen resolution and keyboard macros
#define SCREEN_WIDTH 1440
#define SCREEN_HEIGHT 900
#define KEY_DOWN(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 1 : 0)
#define KEY_UP(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 0 : 1)

// include the Direct3D Library files
#pragma comment (lib, "d3d9.lib")
#pragma comment (lib, "d3dx9.lib")

// global declarations
LPDIRECT3D9 d3d;    // the pointer to our Direct3D interface
LPDIRECT3DDEVICE9 d3ddev;    // the pointer to the device class

// texture declarations
LPDIRECT3DTEXTURE9 texture_1;    // our first texture

// mesh declatations
LPD3DXMESH meshSpaceship;
D3DMATERIAL9* material;    // define the material object
LPDIRECT3DTEXTURE9* texture;    // a pointer to a texture
DWORD numMaterials;

// function prototypes
void initD3D(HWND hWnd);    // sets up and initializes Direct3D
void render_frame(void);    // renders a single frame
void cleanD3D(void);    // closes Direct3D and releases memory
void init_graphics(void);    // 3D declarations
void init_light(void);    // sets up the light and the material

struct CUSTOMVERTEX {FLOAT X, Y, Z; D3DVECTOR NORMAL; FLOAT U, V;};
#define CUSTOMFVF (D3DFVF_XYZ | D3DFVF_NORMAL | D3DFVF_TEX1)

// the WindowProc function prototype
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);


// the entry point for any Windows program
int WINAPI WinMain(HINSTANCE hInstance,
                   HINSTANCE hPrevInstance,
                   LPSTR lpCmdLine,
                   int nCmdShow)
{
    HWND hWnd;
    WNDCLASSEX wc;

    ZeroMemory(&wc, sizeof(WNDCLASSEX));

    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = (WNDPROC)WindowProc;
    wc.hInstance = hInstance;
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.lpszClassName = L"WindowClass";

    RegisterClassEx(&wc);

    hWnd = CreateWindowEx(NULL, L"WindowClass", L"Our Direct3D Program",
                          WS_EX_TOPMOST | WS_POPUP, 0, 0, SCREEN_WIDTH, SCREEN_HEIGHT,
                          NULL, NULL, hInstance, NULL);

    ShowWindow(hWnd, nCmdShow);

    // set up and initialize Direct3D
    initD3D(hWnd);

    // enter the main loop:

    MSG msg;

    while(TRUE)
    {
        DWORD starting_point = GetTickCount();

        if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            if (msg.message == WM_QUIT)
                break;

            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }

        render_frame();

        // check the 'escape' key
        if(KEY_DOWN(VK_ESCAPE))
            PostMessage(hWnd, WM_DESTROY, 0, 0);

        while ((GetTickCount() - starting_point) < 25);
    }

    // clean up DirectX and COM
    cleanD3D();

    return msg.wParam;
}


// this is the main message handler for the program
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch(message)
    {
        case WM_DESTROY:
            {
                PostQuitMessage(0);
                return 0;
            } break;
    }

    return DefWindowProc (hWnd, message, wParam, lParam);
}


// this function initializes and prepares Direct3D for use
void initD3D(HWND hWnd)
{
    d3d = Direct3DCreate9(D3D_SDK_VERSION);

    D3DPRESENT_PARAMETERS d3dpp;

    ZeroMemory(&d3dpp, sizeof(d3dpp));
    d3dpp.Windowed = FALSE;
    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3dpp.hDeviceWindow = hWnd;
    d3dpp.BackBufferFormat = D3DFMT_X8R8G8B8;
    d3dpp.BackBufferWidth = SCREEN_WIDTH;
    d3dpp.BackBufferHeight = SCREEN_HEIGHT;
    d3dpp.EnableAutoDepthStencil = TRUE;
    d3dpp.AutoDepthStencilFormat = D3DFMT_D16;

    // create a device class using this information and the info from the d3dpp stuct
    d3d->CreateDevice(D3DADAPTER_DEFAULT,
                      D3DDEVTYPE_HAL,
                      hWnd,
                      D3DCREATE_SOFTWARE_VERTEXPROCESSING,
                      &d3dpp,
                      &d3ddev);

    init_graphics();    // call the function to initialize the cube
    init_light();    // call the function to initialize the light and material

    d3ddev->SetRenderState(D3DRS_LIGHTING, TRUE);    // turn on the 3D lighting
    d3ddev->SetRenderState(D3DRS_ZENABLE, TRUE);    // turn on the z-buffer
    d3ddev->SetRenderState(D3DRS_AMBIENT, D3DCOLOR_XRGB(50, 50, 50));    // ambient light

    return;
}


// this is the function used to render a single frame
void render_frame(void)
{
    d3ddev->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0);
    d3ddev->Clear(0, NULL, D3DCLEAR_ZBUFFER, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0);

    d3ddev->BeginScene();

    // set the view transform
    D3DXMATRIX matView;    // the view transform matrix
    D3DXMatrixLookAtLH(&matView,
    &D3DXVECTOR3 (0.0f, 8.0f, 25.0f),    // the camera position
    &D3DXVECTOR3 (0.0f, 0.0f, 0.0f),      // the look-at position
    &D3DXVECTOR3 (0.0f, 1.0f, 0.0f));    // the up direction
    d3ddev->SetTransform(D3DTS_VIEW, &matView);

    // set the projection transform
    D3DXMATRIX matProjection;    // the projection transform matrix
    D3DXMatrixPerspectiveFovLH(&matProjection,
                               D3DXToRadian(45),    // the horizontal field of view
                               (FLOAT)SCREEN_WIDTH / (FLOAT)SCREEN_HEIGHT, // aspect ratio
                               1.0f,    // the near view-plane
                               100.0f);    // the far view-plane
    d3ddev->SetTransform(D3DTS_PROJECTION, &matProjection);

    // set the world transform
    static float index = 0.0f; index+=0.03f;    // an ever-increasing float value
    D3DXMATRIX matRotateY;    // a matrix to store the rotation for each triangle
    D3DXMatrixRotationY(&matRotateY, index);    // the rotation matrix
    d3ddev->SetTransform(D3DTS_WORLD, &(matRotateY));    // set the world transform

    // draw the spaceship
    for(DWORD i = 0; i < numMaterials; i++)    // loop through each subset
    {
        d3ddev->SetMaterial(&material[i]);    // set the material for the subset
		if(texture[i] != NULL)    // if the subset has a texture (if texture is not NULL)
			d3ddev->SetTexture(0, texture[i]);    // ...then set the texture

        meshSpaceship->DrawSubset(i);    // draw the subset
    }

    d3ddev->EndScene(); 

    d3ddev->Present(NULL, NULL, NULL, NULL);

    return;
}


// this is the function that cleans up Direct3D and COM
void cleanD3D(void)
{
    meshSpaceship->Release();    // close and release the spaceship mesh
    d3ddev->Release();    // close and release the 3D device
    d3d->Release();    // close and release Direct3D

    return;
}


// this is the function that puts the 3D models into video RAM
void init_graphics(void)
{
	LPD3DXBUFFER bufShipMaterial;

    D3DXLoadMeshFromX(L"airplane 2.x",    // load this file
                      D3DXMESH_SYSTEMMEM,    // load the mesh into system memory
                      d3ddev,    // the Direct3D Device
                      NULL,    // we aren't using adjacency
                      &bufShipMaterial,    // put the materials here
                      NULL,    // we aren't using effect instances
                      &numMaterials,    // the number of materials in this model
                      &meshSpaceship);    // put the mesh here

    // retrieve the pointer to the buffer containing the material information
    D3DXMATERIAL* tempMaterials = (D3DXMATERIAL*)bufShipMaterial->GetBufferPointer();

    // create a new material buffer for each material and texture in the mesh
    material = new D3DMATERIAL9[numMaterials];
	texture = new LPDIRECT3DTEXTURE9[numMaterials];

    for(DWORD i = 0; i < numMaterials; i++)    // for each material...
    {
        material[i] = tempMaterials[i].MatD3D;    // get the material info
        material[i].Ambient = material[i].Diffuse;    // make ambient the same as diffuse
        // if there is a texture to load, load it
        if(FAILED(D3DXCreateTextureFromFile(d3ddev,
                                            tempMaterials[i].pTextureFilename,
                                            &texture[i])))
        texture[i] = NULL;    // if there is no texture, set the texture to NULL
    }

    return;
}


// this is the function that sets up the lights and materials
void init_light(void)
{
    D3DLIGHT9 light;    // create the light struct
    D3DMATERIAL9 material;    // create the material struct

    ZeroMemory(&light, sizeof(light));    // clear out the struct for use
    light.Type = D3DLIGHT_DIRECTIONAL;    // make the light type 'directional light'
    light.Diffuse.r = 0.5f;    // .5 red
    light.Diffuse.g = 0.5f;    // .5 green
    light.Diffuse.b = 0.5f;    // .5 blue
    light.Diffuse.a = 1.0f;    // full alpha (we'll get to that soon)

    D3DVECTOR vecDirection = {-1.0f, -0.3f, -1.0f};    // the direction of the light
    light.Direction = vecDirection;    // set the direction

    d3ddev->SetLight(0, &light);    // send the light struct properties to light #0
    d3ddev->LightEnable(0, TRUE);    // turn on light #0

    ZeroMemory(&material, sizeof(D3DMATERIAL9));    // clear out the struct for use
    material.Diffuse.r = material.Ambient.r = 1.0f;    // set the material to full red
    material.Diffuse.g = material.Ambient.g = 1.0f;    // set the material to full green
    material.Diffuse.b = material.Ambient.b = 1.0f;    // set the material to full blue
    material.Diffuse.a = material.Ambient.a = 1.0f;    // set the material to full alpha

    d3ddev->SetMaterial(&material);    // set the globably-used material to &material

    return;
}

The origenal source used the ATL functions USES_CONVERSION and CA2W to get arround this. But as I don't have ATL (express edition) I removed these. If I run the code above I get:
(246) : error C2664: 'D3DXCreateTextureFromFileW' : cannot convert parameter 2 from 'LPSTR' to 'LPCWSTR'
        Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

So I tried a traditional style cast and a reinterpret cast. Both produced the same result, the airplane 2.x model displaying correctly but with no textures. This is the bit that I changed:
if(FAILED(D3DXCreateTextureFromFile(d3ddev,
                                            (LPCWSTR)tempMaterials[i].pTextureFilename,
                                            &texture[i])))
        texture[i] = NULL;    // if there is no texture, set the texture to NULL

I don't know what a function cast is though presumably, that is what CA2W is. If I plug in the name of one of the textures it works correctly although only using the texture specified:
if(FAILED(D3DXCreateTextureFromFile(d3ddev,
                                            L"wings.bmp",
                                            &texture[i])))
        texture[i] = NULL;    // if there is no texture, set the texture to NULL

Does anyone know of a work around for this? Is there another way to convert tempMaterials[i].pTextureFilename from a LPSTR to a LPCWSTR? Or is there a better way to do it somwhere else? Any help is apreciated on this matter. (BTW, the airplane 2.x comes with the sdk I believe)

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This error is caused by the newer visual studios defaulting to unicode/wide char strings on new projects(IIRC). You can simply place #undefine UNICODE at the top of your source code. Or you can go into your Project Properties->Configuration Properties->Character Set->Set to Multi-Byte

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ChaosPhoenix got it right. I switched from Unicode to multibyte and removed all the 'L's before strings and it now works. Thanks a bunch!

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Quote:
Original post by tcsavage
ChaosPhoenix got it right. I switched from Unicode to multibyte and removed all the 'L's before strings and it now works. Thanks a bunch!


Really you should be going the other way with this...using Unicode everywhere is generally a much better idea in terms of being future-proof and multi-language friendly. But I'm sure you're just looking to learn the basics of Direct3D here, so that's fine. Just something you should keep in mind if you find yourself writing Windows apps that other people will use.

Also I say this all the time so I'll say it again: don't cast things unless you know what you're doing and you know exactly why you need that cast. Using casts as a knee-jerk response to compiler errors is bad bad practice, since many times things will actually seem work fine...until later you encounter a bizarre and seemingly unrelated error caused by stack or heap corruption. In this case you took a pointer to single-byte characters and jammed it into a parameter that was expecting a pointer to double-byte characters. This means the poor D3DXCreateTextureFromFile function had no idea what you did, and read that block of memory as if it were double-byte characters.

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Just use D3DXCreateTextureFromFileA if you want to pass a char* string in a unicode program.

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