D3DXMatrixLookAtLH( &m_mView, pvEyePt, pvLookatPt, &vUp );

    D3DXMATRIX mInvView;
    D3DXMatrixInverse( &mInvView, NULL, &m_mView );

    // The axis basis vectors and camera position are stored inside the 
    // position matrix in the 4 rows of the camera's world matrix.
    // To figure out the yaw/pitch of the camera, we just need the Z basis vector
    D3DXVECTOR3* pZBasis = (D3DXVECTOR3*) &mInvView._31;

    m_fCameraYawAngle   = atan2f( pZBasis->x, pZBasis->z );
    float fLen = sqrtf(pZBasis->z*pZBasis->z + pZBasis->x*pZBasis->x);
    m_fCameraPitchAngle = -atan2f( pZBasis->y, fLen );
}




//--------------------------------------------------------------------------------------
// Calculates the projection matrix based on input params
//--------------------------------------------------------------------------------------
VOID CBaseCamera::SetProjParams( FLOAT fFOV, FLOAT fAspect, FLOAT fNearPlane,
                                   FLOAT fFarPlane )
{
    // Set attributes for the projection matrix
    m_fFOV        = fFOV;
    m_fAspect     = fAspect;
    m_fNearPlane  = fNearPlane;
    m_fFarPlane   = fFarPlane;

    D3DXMatrixPerspectiveFovLH( &m_mProj, fFOV, fAspect, fNearPlane, fFarPlane );
}




//--------------------------------------------------------------------------------------
// Call this from your message proc so this class can handle window messages
//--------------------------------------------------------------------------------------
LRESULT CBaseCamera::HandleMessages( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam )
{
    UNREFERENCED_PARAMETER( hWnd );
    UNREFERENCED_PARAMETER( lParam );

    switch( uMsg )
    {
        case WM_KEYDOWN:
        {
            // Map this key to a D3DUtil_CameraKeys enum and update the
            // state of m_aKeys[] by adding the KEY_WAS_DOWN_MASK|KEY_IS_DOWN_MASK mask
            // only if the key is not down
            D3DUtil_CameraKeys mappedKey = MapKey( (UINT)wParam );
            if( mappedKey != CAM_UNKNOWN )
            {
                if( FALSE == IsKeyDown(m_aKeys[mappedKey]) )
                {
                    m_aKeys[ mappedKey ] = KEY_WAS_DOWN_MASK | KEY_IS_DOWN_MASK;
                    ++m_cKeysDown;
                }
            }
            break;
        }

        case WM_KEYUP:
        {
            // Map this key to a D3DUtil_CameraKeys enum and update the
            // state of m_aKeys[] by removing the KEY_IS_DOWN_MASK mask.
            D3DUtil_CameraKeys mappedKey = MapKey( (UINT)wParam );
            if( mappedKey != CAM_UNKNOWN && (DWORD)mappedKey < 8 )
            {
                m_aKeys[ mappedKey ] &= ~KEY_IS_DOWN_MASK;
                --m_cKeysDown;
            }
            break;
        }

        case WM_RBUTTONDOWN:
        case WM_MBUTTONDOWN:
        case WM_LBUTTONDOWN:
        case WM_RBUTTONDBLCLK:
        case WM_MBUTTONDBLCLK:
        case WM_LBUTTONDBLCLK:
        {
            // Compute the drag rectangle in screen coord.
            POINT ptCursor = { (short)LOWORD(lParam), (short)HIWORD(lParam) };

            // Update member var state
            if( ( uMsg == WM_LBUTTONDOWN || uMsg == WM_LBUTTONDBLCLK ) && PtInRect( &m_rcDrag, ptCursor ) )
                { m_bMouseLButtonDown = true; m_nCurrentButtonMask |= MOUSE_LEFT_BUTTON; }
            if( ( uMsg == WM_MBUTTONDOWN || uMsg == WM_MBUTTONDBLCLK ) && PtInRect( &m_rcDrag, ptCursor ) )
                { m_bMouseMButtonDown = true; m_nCurrentButtonMask |= MOUSE_MIDDLE_BUTTON; }
            if( ( uMsg == WM_RBUTTONDOWN || uMsg == WM_RBUTTONDBLCLK ) && PtInRect( &m_rcDrag, ptCursor ) )
                { m_bMouseRButtonDown = true; m_nCurrentButtonMask |= MOUSE_RIGHT_BUTTON; }

            // Capture the mouse, so if the mouse button is 
            // released outside the window, we'll get the WM_LBUTTONUP message
            SetCapture(hWnd);
            GetCursorPos( &m_ptLastMousePosition );
            return TRUE;
        }

        case WM_RBUTTONUP: 
        case WM_MBUTTONUP: 
        case WM_LBUTTONUP:   
        {
            // Update member var state
            if( uMsg == WM_LBUTTONUP ) { m_bMouseLButtonDown = false; m_nCurrentButtonMask &= ~MOUSE_LEFT_BUTTON; }
            if( uMsg == WM_MBUTTONUP ) { m_bMouseMButtonDown = false; m_nCurrentButtonMask &= ~MOUSE_MIDDLE_BUTTON; }
            if( uMsg == WM_RBUTTONUP ) { m_bMouseRButtonDown = false; m_nCurrentButtonMask &= ~MOUSE_RIGHT_BUTTON; }

            // Release the capture if no mouse buttons down
            if( !m_bMouseLButtonDown  && 
                !m_bMouseRButtonDown &&
                !m_bMouseMButtonDown )
            {
                ReleaseCapture();
            }
            break;
        }

        case WM_CAPTURECHANGED:
        {
            if( (HWND)lParam != hWnd )
            {
                if( (m_nCurrentButtonMask & MOUSE_LEFT_BUTTON) ||
                    (m_nCurrentButtonMask & MOUSE_MIDDLE_BUTTON) ||
                    (m_nCurrentButtonMask & MOUSE_RIGHT_BUTTON) )
                {
                    m_bMouseLButtonDown = false;
                    m_bMouseMButtonDown = false;
                    m_bMouseRButtonDown = false;
                    m_nCurrentButtonMask &= ~MOUSE_LEFT_BUTTON;
                    m_nCurrentButtonMask &= ~MOUSE_MIDDLE_BUTTON;
                    m_nCurrentButtonMask &= ~MOUSE_RIGHT_BUTTON;
                    ReleaseCapture();
                }
            }
            break;
        }

        case WM_MOUSEWHEEL: 
            // Update member var state
            m_nMouseWheelDelta = (short)HIWORD(wParam) / 120;
            break;
    }

    return FALSE;
}


//--------------------------------------------------------------------------------------
// Figure out the velocity based on keyboard input & drag if any
//--------------------------------------------------------------------------------------
void CBaseCamera::GetInput( bool bGetKeyboardInput, bool bGetMouseInput, bool bGetGamepadInput, bool bResetCursorAfterMove )
{
    m_vKeyboardDirection = D3DXVECTOR3(0,0,0);
    if( bGetKeyboardInput )
    {
        // Update acceleration vector based on keyboard state
        if( IsKeyDown(m_aKeys[CAM_MOVE_FORWARD]) )
            m_vKeyboardDirection.z += 1.0f;
        if( IsKeyDown(m_aKeys[CAM_MOVE_BACKWARD]) )
            m_vKeyboardDirection.z -= 1.0f;
        if( m_bEnableYAxisMovement )
        {
            if( IsKeyDown(m_aKeys[CAM_MOVE_UP]) )
                m_vKeyboardDirection.y += 1.0f;
            if( IsKeyDown(m_aKeys[CAM_MOVE_DOWN]) )
                m_vKeyboardDirection.y -= 1.0f;
        }
        if( IsKeyDown(m_aKeys[CAM_STRAFE_RIGHT]) )
            m_vKeyboardDirection.x += 1.0f;
        if( IsKeyDown(m_aKeys[CAM_STRAFE_LEFT]) )
            m_vKeyboardDirection.x -= 1.0f;
    }

    if( bGetMouseInput )
    {
        // Get current position of mouse
        POINT ptCurMouseDelta;
        POINT ptCurMousePos;
        
        if( GetCursorPos( &ptCurMousePos ) )
        {
            // Calc how far it's moved since last frame
            ptCurMouseDelta.x = ptCurMousePos.x - m_ptLastMousePosition.x;
            ptCurMouseDelta.y = ptCurMousePos.y - m_ptLastMousePosition.y;
            
            // Record current position for next time
            m_ptLastMousePosition = ptCurMousePos;
        }
        else
        {
            // If GetCursorPos() returns false, just set delta to zero
            ptCurMouseDelta.x = 0;
            ptCurMouseDelta.y = 0;
        }

        if( bResetCursorAfterMove && DXUTIsActive() )
        {
            // Set position of camera to center of desktop, 
            // so it always has room to move.  This is very useful
            // if the cursor is hidden.  If this isn't done and cursor is hidden, 
            // then invisible cursor will hit the edge of the screen 
            // and the user can't tell what happened
            POINT ptCenter;

            // Get the center of the current monitor
            MONITORINFO mi;
            mi.cbSize = sizeof(MONITORINFO);
            DXUTGetMonitorInfo( DXUTMonitorFromWindow(DXUTGetHWND(),MONITOR_DEFAULTTONEAREST), &mi );
            ptCenter.x = (mi.rcMonitor.left + mi.rcMonitor.right) / 2;
            ptCenter.y = (mi.rcMonitor.top + mi.rcMonitor.bottom) / 2;   
            SetCursorPos( ptCenter.x, ptCenter.y );
            m_ptLastMousePosition = ptCenter;
        }

        // Smooth the relative mouse data over a few frames so it isn't 
        // jerky when moving slowly at low frame rates.
        float fPercentOfNew =  1.0f / m_fFramesToSmoothMouseData;
        float fPercentOfOld =  1.0f - fPercentOfNew;
        m_vMouseDelta.x = m_vMouseDelta.x*fPercentOfOld + ptCurMouseDelta.x*fPercentOfNew;
        m_vMouseDelta.y = m_vMouseDelta.y*fPercentOfOld + ptCurMouseDelta.y*fPercentOfNew;

    }

    if( bGetGamepadInput )
    {
        m_vGamePadLeftThumb = D3DXVECTOR3(0,0,0);
        m_vGamePadRightThumb = D3DXVECTOR3(0,0,0);

        // Get controller state
        for( DWORD iUserIndex=0; iUserIndex<DXUT_MAX_CONTROLLERS; iUserIndex++ )
        {
            DXUTGetGamepadState( iUserIndex, &m_GamePad[iUserIndex], true, true );

            // Mark time if the controller is in a non-zero state
            if( m_GamePad[iUserIndex].wButtons || 
                m_GamePad[iUserIndex].sThumbLX || m_GamePad[iUserIndex].sThumbLX || 
                m_GamePad[iUserIndex].sThumbRX || m_GamePad[iUserIndex].sThumbRY || 
                m_GamePad[iUserIndex].bLeftTrigger || m_GamePad[iUserIndex].bRightTrigger )
            {
                m_GamePadLastActive[iUserIndex] = DXUTGetTime();
            }
        }

        // Find out which controller was non-zero last
        int iMostRecentlyActive = -1;
        double fMostRecentlyActiveTime = 0.0f;
        for( DWORD iUserIndex=0; iUserIndex<DXUT_MAX_CONTROLLERS; iUserIndex++ )
        {
            if( m_GamePadLastActive[iUserIndex] > fMostRecentlyActiveTime )
            {
                fMostRecentlyActiveTime = m_GamePadLastActive[iUserIndex];
                iMostRecentlyActive = iUserIndex;
            }
        }

        // Use the most recent non-zero controller if its connected
        if( iMostRecentlyActive >= 0 && m_GamePad[iMostRecentlyActive].bConnected )
        {
            m_vGamePadLeftThumb.x = m_GamePad[iMostRecentlyActive].fThumbLX;
            m_vGamePadLeftThumb.y = 0.0f;
            m_vGamePadLeftThumb.z = m_GamePad[iMostRecentlyActive].fThumbLY;

            m_vGamePadRightThumb.x = m_GamePad[iMostRecentlyActive].fThumbRX;
            m_vGamePadRightThumb.y = 0.0f;
            m_vGamePadRightThumb.z = m_GamePad[iMostRecentlyActive].fThumbRY;
        }
    }
}


//--------------------------------------------------------------------------------------
// Figure out the velocity based on keyboard input & drag if any
//--------------------------------------------------------------------------------------
void CBaseCamera::UpdateVelocity( float fElapsedTime )
{
    D3DXMATRIX mRotDelta;

    D3DXVECTOR2 vGamePadRightThumb = D3DXVECTOR2(m_vGamePadRightThumb.x, -m_vGamePadRightThumb.z);
    m_vRotVelocity = m_vMouseDelta * m_fRotationScaler + vGamePadRightThumb * 0.02f;

    D3DXVECTOR3 vAccel = m_vKeyboardDirection + m_vGamePadLeftThumb;

    // Normalize vector so if moving 2 dirs (left & forward), 
    // the camera doesn't move faster than if moving in 1 dir
    D3DXVec3Normalize( &vAccel, &vAccel );

    // Scale the acceleration vector
    vAccel *= m_fMoveScaler;

    if( m_bMovementDrag )
    {
        // Is there any acceleration this frame?
        if( D3DXVec3LengthSq( &vAccel ) > 0 )
        {
            // If so, then this means the user has pressed a movement key\
            // so change the velocity immediately to acceleration 
            // upon keyboard input.  This isn't normal physics
            // but it will give a quick response to keyboard input
            m_vVelocity = vAccel;
            m_fDragTimer = m_fTotalDragTimeToZero;
            m_vVelocityDrag = vAccel / m_fDragTimer;
        }
        else 
        {
            // If no key being pressed, then slowly decrease velocity to 0
            if( m_fDragTimer > 0 )
            {
                // Drag until timer is <= 0
                m_vVelocity -= m_vVelocityDrag * fElapsedTime;
                m_fDragTimer -= fElapsedTime;
            }
            else
            {
                // Zero velocity
                m_vVelocity = D3DXVECTOR3(0,0,0);
            }
        }
    }
    else
    {
        // No drag, so immediately change the velocity
        m_vVelocity = vAccel;
    }
}




//--------------------------------------------------------------------------------------
// Clamps pV to lie inside m_vMinBoundary & m_vMaxBoundary
//-------------------------------------------------