我想画个圆柱体
下面是显示代码：

bool Display(float timeDelta)
{
    if( Device )
    {
        static float angle  = (3.0f * D3DX_PI) / 2.0f;
        static float height = 5.0f;
        if( ::GetAsyncKeyState(VK_LEFT) & 0x8000f )
            angle -= 0.5f * timeDelta;

        if( ::GetAsyncKeyState(VK_RIGHT) & 0x8000f )
            angle += 0.5f * timeDelta;

        if( ::GetAsyncKeyState(VK_UP) & 0x8000f )
            height += 5.0f * timeDelta;
        if( ::GetAsyncKeyState(VK_DOWN) & 0x8000f )
            height -= 5.0f * timeDelta;        
        D3DXVECTOR3 position( cosf(angle) * 7.0f, height, sinf(angle) * 7.0f );
        D3DXVECTOR3 target(0.0f, 0.0f, 0.0f);
        D3DXVECTOR3 up(0.0f, 1.0f, 0.0f);
        D3DXMATRIX V;
        D3DXMatrixLookAtLH(&V, &position, &target, &up);
        Device->SetTransform(D3DTS_VIEW, &V);
        Device->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0x00000000, 1.0f, 0);
        Device->BeginScene();
        if((float)timeGetTime()-timenow<500)
        {
            for(int i = 0; i < 3; i++)
            {
                Device->SetMaterial(&Mtrls[i]);
                Device->SetTransform(D3DTS_WORLD, &Worlds[i]);
                Objects[i]->DrawSubset(0);
            }
        }
        else
        {
            //timenow=(float)timeGetTime();
            srand((unsigned)time(NULL));
            int r=rand()%6;
            D3DXMATRIX Rx,Ry,Rz,R,p;
            D3DXMatrixRotationX(&Rx,(float)atan(DirectionSet[r][1]/DirectionSet[r][2]));
            D3DXMatrixRotationX(&Ry,(float)atan(DirectionSet[r][2]/DirectionSet[r][0]));
            D3DXMatrixRotationX(&Rz,(float)atan(DirectionSet[r][0]/DirectionSet[r][1]));
            D3DXMatrixTranslation(&p,len[0]*DirectionSet[r][0]/2,len[0]*DirectionSet[r][1]/2,len[0]*DirectionSet[r][2]/2);
            p=Rx*Ry*Rz*R;
            Device->SetTransform(D3DTS_WORLD,&p);
            Device->SetMaterial(&Mtrls[0]);
            Objects[0]->DrawSubset(0);
        }
        Device->EndScene();
        Device->Present(0, 0, 0, 0);
    }
    return true;
}

我就一共定义了6个方向，我想让它0.5s以后随机转变方向

float len[3]={0.5f,2.0f,2.5f};
float CurrentDirection[3][3]={0.0f,0.0f,1.0f,0.0f,0.0f,1.0f,0.0f,0.0f,0.0f};
float DirectionSet[6][3]={1.0f,0.01f,0.01f,0.01f,0.01f,1.0f,-1.0f,0.01f,0.01f,0.01f,0.01f,-1.0f,0.01f,1.0f,0.01f,0.01f,-1.0f,0.01f};

但是0.5s以后它画出来的怎么是乱七八糟的东西，连圆柱都没有了？
第一个图一开始的0.5s内显示出来的东西

二三图是之后显示出来的东西