Первый опыт с DirectX9. Странное поведение программы

// include the basic windows header files and the Direct3D header file
#include <windows.h>
#include <windowsx.h>
#include <d3d9.h>
 
 
// define the screen resolution
#define SCREEN_WIDTH 800
#define SCREEN_HEIGHT 600
 
// include the Direct3D Library file
#pragma comment (lib, "d3d9.lib")
 
// global declarations
LPDIRECT3D9 d3d;    // the pointer to our Direct3D interface
LPDIRECT3DDEVICE9 d3ddev;    // the pointer to the device class
LPDIRECT3DVERTEXBUFFER9 v_buffer = NULL;    // the pointer to the vertex buffer
 
// 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
 
 
inline POINT mouse_coord();
int isLButtonDown();
int isRButtonDown();
int click_info(int *x1,int *y1,int *x2,int *y2);
int drawbar(const int x1,const int y1,const int x2,const int y2,const int color1,const int color2,const int color3);
 
 
struct CUSTOMVERTEX {FLOAT X, Y, Z, RHW; DWORD COLOR;};
#define CUSTOMFVF (D3DFVF_XYZRHW | D3DFVF_DIFFUSE)
 
// 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 = WindowProc;
    wc.hInstance = hInstance;
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.lpszClassName = "WindowClass";
 
    RegisterClassEx(&wc);
 
    hWnd = CreateWindowEx(NULL,
                          "WindowClass",
                          "Our Direct3D Program",
                          WS_OVERLAPPEDWINDOW,
                          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;
    
    for(int i=0;i<5;i++){
        const int s=50;
        drawbar(s*i,s*i,s*i+s,s*i+s,255,255,255);
    
    }
    while(TRUE)
    {
        while(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
 
        if(msg.message == WM_QUIT)
            break;
        
        if(isLButtonDown())
        {
            int x1,y1,x2,y2;            
            click_info(&x1,&y1,&x2,&y2);
            drawbar(x1,y1,x2,y2,0,100,100);
        }
 
    }
 
    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;
 
    // 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);
                        d3ddev->SetFVF(CUSTOMFVF);
    //d3ddev->SetFVF(CUSTOMFVF);
    //d3ddev->SetStreamSource(0, v_buffer, 0, sizeof(CUSTOMVERTEX));
 
}
 
 
 
// this is the function that cleans up Direct3D and COM
void cleanD3D(void)
{
    v_buffer->Release();    // close and release the vertex buffer
    d3ddev->Release();    // close and release the 3D device
    d3d->Release();    // close and release Direct3D
}
 
 
 
inline POINT mouse_coord(){
    POINT rez;
    GetCursorPos(&rez);
    return rez;
}///Возвращает понятно что - объект точку координаты мыши
 
int isLButtonDown()
{
  SHORT state = GetAsyncKeyState(VK_LBUTTON);
  return (state & 0x8000) != 0; // == 0 - just to force bool value 
}
 
int isRButtonDown()
{
  SHORT state = GetAsyncKeyState(VK_RBUTTON);
  return (state & 0x8000) != 0; // == 0 - just to force bool value 
}
 
 
int click_info(int *x1,int *y1,int *x2,int *y2)
{
    POINT buff;
    int FLAG=0;
    for(;FLAG==0;)
    {
        if(isLButtonDown()){FLAG=1;}
        if(isRButtonDown()){FLAG=2;}
    }
    buff=mouse_coord();
    *x1=buff.x;
    *y1=buff.y;
    
    if(FLAG==1){for(;isLButtonDown();){}}
    if(FLAG==2){for(;isRButtonDown();){}}
    buff=mouse_coord();
    *x2=buff.x;
    *y2=buff.y;
    
    return FLAG;
}
 
 
 
 
int drawbar(const int x1,const int y1,const int x2,const int y2,const int color1,const int color2,const int color3)
{
    const double _x1=x1;
    const double _y1=y1;
    const double _x2=x2;
    const double _y2=y2;
    
    const int C1=color1;
    const int C2=color2;
    const int C3=color3;
        
    CUSTOMVERTEX vertices[] =
    {
        {_x1,_y1, 0.5f, 1.0f, D3DCOLOR_XRGB(C1,C2,C3),},
        {_x2,_y1, 0.5f, 1.0f, D3DCOLOR_XRGB(C1,C2,C3),},
        {_x1,_y2, 0.5f, 1.0f, D3DCOLOR_XRGB(C1,C2,C3),},
        {_x2,_y1, 0.5f, 1.0f, D3DCOLOR_XRGB(C1,C2,C3),},
        {_x2,_y2, 0.5f, 1.0f, D3DCOLOR_XRGB(C1,C2,C3),},
        {_x1,_y2, 0.5f, 1.0f, D3DCOLOR_XRGB(C1,C2,C3),},
    };
 
    d3ddev->CreateVertexBuffer(6*sizeof(CUSTOMVERTEX),
                               0,
                               CUSTOMFVF,
                               D3DPOOL_MANAGED,
                               &v_buffer,
                               NULL);
 
    VOID* pVoid;    // a void pointer
 
    v_buffer->Lock(0, 0, (void**)&pVoid, 0);
    memcpy(pVoid, vertices, sizeof(vertices));
    v_buffer->Unlock();
    
    ///////////////////
    
    d3ddev->BeginScene();
    
    d3ddev->SetFVF(CUSTOMFVF);
    d3ddev->SetStreamSource(0, v_buffer, 0, sizeof(CUSTOMVERTEX));
    d3ddev->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 2);
 
    d3ddev->EndScene();
 
    d3ddev->Present(NULL, NULL, NULL, NULL);
 
    return 0;
}

d3dpp.SwapEffect = D3DSWAPEFFECT_D[B]ISCARD[/B];

d3dpp.SwapEffect = D3DSWAPEFFECT_[B]COPY[/B];