dxutmisc.cpp

在GPU上实现数值模拟技术（线性方程组）的通用架构

        ptCenter.x = (rcDesktop.right - rcDesktop.left) / 2;
        ptCenter.y = (rcDesktop.bottom - rcDesktop.top) / 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;

    m_vRotVelocity = m_vMouseDelta * m_fRotationScaler;
}




//--------------------------------------------------------------------------------------
// Figure out the velocity based on keyboard input & drag if any
//--------------------------------------------------------------------------------------
void CBaseCamera::UpdateVelocity( float fElapsedTime )
{
    D3DXMATRIX mRotDelta;
    D3DXVECTOR3 vAccel = D3DXVECTOR3(0,0,0);

    if( m_bEnablePositionMovement )
    {
        // Update acceleration vector based on keyboard state
        if( IsKeyDown(m_aKeys[CAM_MOVE_FORWARD]) )
            vAccel.z += 1.0f;
        if( IsKeyDown(m_aKeys[CAM_MOVE_BACKWARD]) )
            vAccel.z -= 1.0f;
        if( m_bEnableYAxisMovement )
        {
            if( IsKeyDown(m_aKeys[CAM_MOVE_UP]) )
                vAccel.y += 1.0f;
            if( IsKeyDown(m_aKeys[CAM_MOVE_DOWN]) )
                vAccel.y -= 1.0f;
        }
        if( IsKeyDown(m_aKeys[CAM_STRAFE_RIGHT]) )
            vAccel.x += 1.0f;
        if( IsKeyDown(m_aKeys[CAM_STRAFE_LEFT]) )
            vAccel.x -= 1.0f;
    }

    // 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
//--------------------------------------------------------------------------------------
void CBaseCamera::ConstrainToBoundary( D3DXVECTOR3* pV )
{
    // Constrain vector to a bounding box 
    pV->x = max(pV->x, m_vMinBoundary.x);
    pV->y = max(pV->y, m_vMinBoundary.y);
    pV->z = max(pV->z, m_vMinBoundary.z);

    pV->x = min(pV->x, m_vMaxBoundary.x);
    pV->y = min(pV->y, m_vMaxBoundary.y);
    pV->z = min(pV->z, m_vMaxBoundary.z);
}




//--------------------------------------------------------------------------------------
// Maps a windows virtual key to an enum
//--------------------------------------------------------------------------------------
D3DUtil_CameraKeys CBaseCamera::MapKey( UINT nKey )
{
    // This could be upgraded to a method that's user-definable but for 
    // simplicity, we'll use a hardcoded mapping.
    switch( nKey )
    {
        case VK_CONTROL:  return CAM_CONTROLDOWN;
        case VK_LEFT:  return CAM_STRAFE_LEFT;
        case VK_RIGHT: return CAM_STRAFE_RIGHT;
        case VK_UP:    return CAM_MOVE_FORWARD;
        case VK_DOWN:  return CAM_MOVE_BACKWARD;
        case VK_PRIOR: return CAM_MOVE_UP;        // pgup
        case VK_NEXT:  return CAM_MOVE_DOWN;      // pgdn

        case 'A':      return CAM_STRAFE_LEFT;
        case 'D':      return CAM_STRAFE_RIGHT;
        case 'W':      return CAM_MOVE_FORWARD;
        case 'S':      return CAM_MOVE_BACKWARD;
        case 'Q':      return CAM_MOVE_DOWN;
        case 'E':      return CAM_MOVE_UP;

        case VK_NUMPAD4: return CAM_STRAFE_LEFT;
        case VK_NUMPAD6: return CAM_STRAFE_RIGHT;
        case VK_NUMPAD8: return CAM_MOVE_FORWARD;
        case VK_NUMPAD2: return CAM_MOVE_BACKWARD;
        case VK_NUMPAD9: return CAM_MOVE_UP;        
        case VK_NUMPAD3: return CAM_MOVE_DOWN;      

        case VK_HOME:   return CAM_RESET;
    }

    return CAM_UNKNOWN;
}




//--------------------------------------------------------------------------------------
// Reset the camera's position back to the default
//--------------------------------------------------------------------------------------
VOID CBaseCamera::Reset()
{
    SetViewParams( &m_vDefaultEye, &m_vDefaultLookAt );
}




//--------------------------------------------------------------------------------------
// Constructor
//--------------------------------------------------------------------------------------
CFirstPersonCamera::CFirstPersonCamera() :
    m_nActiveButtonMask( 0x07 )
{
}




//--------------------------------------------------------------------------------------
// Update the view matrix based on user input & elapsed time
//--------------------------------------------------------------------------------------
VOID CFirstPersonCamera::FrameMove( FLOAT fElapsedTime )
{
    if( DXUTGetGlobalTimer()->IsStopped() )         
        fElapsedTime = 1.0f / DXUTGetFPS();

    if( IsKeyDown(m_aKeys[CAM_RESET]) )
        Reset();

    // Get the mouse movement (if any) if the mouse button are down
    if( m_nActiveButtonMask & m_nCurrentButtonMask )
        UpdateMouseDelta( fElapsedTime );

    // Get amount of velocity based on the keyboard input and drag (if any)
    UpdateVelocity( fElapsedTime );

    // Simple euler method to calculate position delta
    D3DXVECTOR3 vPosDelta = m_vVelocity * fElapsedTime;

    // If rotating the camera 
    if( m_nActiveButtonMask & m_nCurrentButtonMask )
    {
        // Update the pitch & yaw angle based on mouse movement
        float fYawDelta   = m_vRotVelocity.x;
        float fPitchDelta = m_vRotVelocity.y;

        // Invert pitch if requested
        if( m_bInvertPitch )
            fPitchDelta = -fPitchDelta;

        m_fCameraPitchAngle += fPitchDelta;
        m_fCameraYawAngle   += fYawDelta;

        // Limit pitch to straight up or straight down
        m_fCameraPitchAngle = max( -D3DX_PI/2.0f,  m_fCameraPitchAngle );
        m_fCameraPitchAngle = min( +D3DX_PI/2.0f,  m_fCameraPitchAngle );
    }

    // Make a rotation matrix based on the camera's yaw & pitch
    D3DXMATRIX mCameraRot;
    D3DXMatrixRotationYawPitchRoll( &mCameraRot, m_fCameraYawAngle, m_fCameraPitchAngle, 0 );

    // Transform vectors based on camera's rotation matrix
    D3DXVECTOR3 vWorldUp, vWorldAhead;
    D3DXVECTOR3 vLocalUp    = D3DXVECTOR3(0,1,0);
    D3DXVECTOR3 vLocalAhead = D3DXVECTOR3(0,0,1);
    D3DXVec3TransformCoord( &vWorldUp, &vLocalUp, &mCameraRot );
    D3DXVec3TransformCoord( &vWorldAhead, &vLocalAhead, &mCameraRot );

    // Transform the position delta by the camera's rotation 
    D3DXVECTOR3 vPosDeltaWorld;
    D3DXVec3TransformCoord( &vPosDeltaWorld, &vPosDelta, &mCameraRot );
    if( !m_bEnableYAxisMovement )
        vPosDeltaWorld.y = 0.0f;

    // Move the eye position 
    m_vEye += vPosDeltaWorld;
    if( m_bClipToBoundary )
        ConstrainToBoundary( &m_vEye );

    // Update the lookAt position based on the eye position 
    m_vLookAt = m_vEye + vWorldAhead;

    // Update the view matrix
    D3DXMatrixLookAtLH( &m_mView, &m_vEye, &m_vLookAt, &vWorldUp );

    D3DXMatrixInverse( &m_mCameraWorld, NULL, &m_mView );
}


//--------------------------------------------------------------------------------------
// Enable or disable each of the mouse buttons for rotation drag.
//--------------------------------------------------------------------------------------
void CFirstPersonCamera::SetRotateButtons( bool bLeft, bool bMiddle, bool bRight )
{
    m_nActiveButtonMask = ( bLeft ? MOUSE_LEFT_BUTTON : 0 ) |
                          ( bMiddle ? MOUSE_MIDDLE_BUTTON : 0 ) |
                          ( bRight ? MOUSE_RIGHT_BUTTON : 0 );
}


//--------------------------------------------------------------------------------------
// Constructor 
//--------------------------------------------------------------------------------------
CModelViewerCamera::CModelViewerCamera()
{
    D3DXMatrixIdentity( &m_mWorld );
    D3DXMatrixIdentity( &m_mModelRot );
    D3DXMatrixIdentity( &m_mModelLastRot );    
    D3DXMatrixIdentity( &m_mCameraRotLast );    
    m_vModelCenter = D3DXVECTOR3(0,0,0);
    m_fRadius    = 5.0f;
    m_fDefaultRadius = 5.0f;
    m_fMinRadius = 1.0f;
    m_fMaxRadius = FLT_MAX;
    m_bLimitPitch = false;
    m_bEnablePositionMovement = false;
    m_bAttachCameraToModel = false;

    m_nRotateModelButtonMask  = MOUSE_LEFT_BUTTON;
    m_nZoomButtonMask         = MOUSE_WHEEL;
    m_nRotateCameraButtonMask = MOUSE_RIGHT_BUTTON;
}




//--------------------------------------------------------------------------------------
// Update the view matrix & the model's world matrix based 
//       on user input & elapsed time
//--------------------------------------------------------------------------------------
VOID CModelViewerCamera::FrameMove( FLOAT fElapsedTime )
{
    if( IsKeyDown(m_aKeys[CAM_RESET]) )
        Reset();

    // Get the mouse movement (if any) if the mouse button are down
    if( m_nCurrentButtonMask != 0 ) 
        UpdateMouseDelta( fElapsedTime );

    // Get amount of velocity based on the keyboard input and drag (if any)
    UpdateVelocity( fElapsedTime );

    // Simple euler method to calculate position delta
    D3DXVECTOR3 vPosDelta = m_vVelocity * fElapsedTime;

    // Change the radius from the camera to the model based on wheel scrolling
    if( m_nMouseWheelDelta && m_nZoomButtonMask == MOUSE_WHEEL )
        m_fRadius -= m_nMouseWheelDelta * m_fRadius * 0.1f;
    m_fRadius = min( m_fMaxRadius, m_fRadius );
    m_fRadius = max( m_fMinRadius, m_fRadius );
    m_nMouseWheelDelta = 0;

    // Get the inverse of the arcball's rotation matrix
    D3DXMATRIX mCameraRot;
    D3DXMatrixInverse( &mCameraRot, NULL, m_ViewArcBall.GetRotationMatrix() );

    // Transform vectors based on camera's rotation matrix
    D3DXVECTOR3 vWorldUp, vWorldAhead;
    D3DXVECTOR3 vLocalUp    = D3DXVECTOR3(0,1,0);
    D3DXVECTOR3 vLocalAhead = D3DXVECTOR3(0,0,1);
    D3DXVec3TransformCoord( &vWorldUp, &vLocalUp, &mCameraRot );
    D3DXVec3TransformCoord( &vWorldAhead, &vLocalAhead, &mCameraRot );

    // Transform the position delta by the camera's rotation 
    D3DXVECTOR3 vPosDeltaWorld;
    D3DXVec3TransformCoord( &vPosDeltaWorld, &vPosDelta, &mCameraRot );

    // Move the lookAt position 
    m_vLookAt += vPosDeltaWorld;
    if( m_bClipToBoundary )
        ConstrainToBoundary( &m_vLookAt );

    // Update the eye point based on a radius away from the lookAt position
    m_vEye = m_vLookAt - vWorldAhead * m_fRadius;

    // Update the view matrix
    D3DXMatrixLookAtLH( &m_mView, &m_vEye, &m_vLookAt, &vWorldUp );

    D3DXMATRIX mInvView;
    D3DXMatrixInverse( &mInvView, NULL, &m_mView );
    mInvView._41 = mInvView._42 = mInvView._43 = 0;

    D3DXMATRIX mModelLastRotInv;
    D3DXMatrixInverse(&mModelLastRotInv, NULL, &m_mModelLastRot);

    // Accumulate the delta of the arcball's rotation in view space.
    // Note that per-frame delta rotations could be problematic over long periods of time.
    D3DXMATRIX mModelRot;
    mModelRot = *m_WorldArcBall.GetRotationMatrix();
    m_mModelRot *= m_mView * mModelLastRotInv * mModelRot * mInvView;

    if( m_ViewArcBall.IsBeingDragged() && m_bAttachCameraToModel && !IsKeyDown(m_aKeys[CAM_CON