使用矩阵和四元数实现三维模型的空间定位

      通过矩阵变换实现绕三个坐标轴的特定角度的旋转:

// -----------------------------------------------------------------------------
//  Desc: 设置世界矩阵
// -----------------------------------------------------------------------------
VOID SetWorldMatrix()
{
    static long curTime=0;
    static float elapsetime=0;
    elapsetime = (timeGetTime()-curTime)/1000.0f;
    curTime = timeGetTime();

    //创建并设置世界矩阵
    float fRoll, fPitch, fYaw;
    fRoll = fPitch = fYaw = 0.0f;

    if (m_bKey['D']) fRoll  -= 3*elapsetime;
    if (m_bKey['A']) fRoll  += 3*elapsetime;

    if (m_bKey['S']) fPitch -= 3*elapsetime;
    if (m_bKey['W']) fPitch += 3*elapsetime;
    
    if (m_bKey['Q']) fYaw   -= 3*elapsetime;
    if (m_bKey['E']) fYaw   += 3*elapsetime;

    //更新网格模型姿态
    static D3DXVECTOR3 vRight, vUp, vLook, vPos;

    vRight.x = g_matWorld._11;
    vRight.y = g_matWorld._12;
    vRight.z = g_matWorld._13;
    vUp.x    = g_matWorld._21;
    vUp.y    = g_matWorld._22;
    vUp.z    = g_matWorld._23;
    vLook.x  = g_matWorld._31;
    vLook.y  = g_matWorld._32;
    vLook.z  = g_matWorld._33;
    vPos.x   = g_matWorld._41;
    vPos.y   = g_matWorld._42;
    vPos.z   = g_matWorld._43;

    D3DXVec3Normalize(&vLook, &vLook);
    D3DXVec3Cross(&vRight, &vUp, &vLook);
    
    D3DXVec3Normalize(&vRight, &vRight);
    D3DXVec3Cross(&vUp, &vLook, &vRight);
    
    D3DXVec3Normalize(&vUp, &vUp);

    static D3DXMATRIX matPitch, matYaw, matRoll;
    
    D3DXMatrixRotationAxis(&matYaw, &vUp, fYaw);
    D3DXVec3TransformCoord(&vLook,  &vLook, &matYaw);
    D3DXVec3TransformCoord(&vRight, &vRight, &matYaw);

    D3DXMatrixRotationAxis(&matRoll, &vLook, fRoll);
    D3DXVec3TransformCoord(&vRight, &vRight, &matRoll);
    D3DXVec3TransformCoord(&vUp,    &vUp, &matRoll);

    D3DXMatrixRotationAxis(&matPitch, &vRight, fPitch);
    D3DXVec3TransformCoord(&vLook, &vLook, &matPitch);
    D3DXVec3TransformCoord(&vUp,   &vUp,  &matPitch);

    g_matWorld._11 = vRight.x;
    g_matWorld._12 = vRight.y;
    g_matWorld._13 = vRight.z;
    g_matWorld._21 = vUp.x ;
    g_matWorld._22 = vUp.y  ;
    g_matWorld._23 = vUp.z;
    g_matWorld._31 = vLook.x;
    g_matWorld._32 = vLook.y;
    g_matWorld._33 = vLook.z;

    //向前移动
    if (m_bKey['F'])
    {
        g_matWorld._41 += 30*elapsetime * vLook.x;
        g_matWorld._42 += 30*elapsetime * vLook.y;
        g_matWorld._43 += 30*elapsetime * vLook.z;
    }

    //向后移动
    if (m_bKey['V']) 
    {
        g_matWorld._41 -= 30*elapsetime * vLook.x;
        g_matWorld._42 -= 30*elapsetime * vLook.y;
        g_matWorld._43 -= 30*elapsetime * vLook.z;
    }
    g_pd3dDevice->SetTransform( D3DTS_WORLD, &g_matWorld );
}

      通过四元数实现绕三个坐标轴的特定角度的旋转:

// -----------------------------------------------------------------------------
//  Desc: 设置世界矩阵
// -----------------------------------------------------------------------------
VOID SetWorldMatrix()
{
    static long curTime=0;
    static float elapsetime=0;
    elapsetime = (timeGetTime()-curTime)/1000.0f;
    curTime = timeGetTime();

    //创建并设置世界矩阵 
    float fRoll, fPitch, fYaw;
    fRoll = fPitch = fYaw = 0.0f;

    if (m_bKey['D']) fRoll  -= 3*elapsetime;
    if (m_bKey['A']) fRoll  +=  3*elapsetime;
    if (m_bKey['S']) fPitch -= 3*elapsetime;
    if (m_bKey['W']) fPitch += 3*elapsetime;
    if (m_bKey['Q']) fYaw   -= 3*elapsetime;
    if (m_bKey['E']) fYaw   += 3*elapsetime;

    //更新网格模型姿态
    D3DXQUATERNION qR;
    D3DXMATRIX matRot;
    D3DXQuaternionRotationYawPitchRoll (&qR, fYaw, fPitch, fRoll);    
    D3DXMatrixRotationQuaternion (&matRot, &qR);
    D3DXMatrixMultiply (&g_matWorld, &matRot, &g_matWorld);

    //获取网格模型前向量
    static D3DXVECTOR3 vLook;
    vLook.x = g_matWorld._31;
    vLook.y = g_matWorld._32;
    vLook.z = g_matWorld._33;

    //向前移动
    if (m_bKey['F'])
    {
        g_matWorld._41 += 10*elapsetime * vLook.x;
        g_matWorld._42 += 10*elapsetime * vLook.y;
        g_matWorld._43 += 10*elapsetime * vLook.z;
    }

    //向后移动
    if (m_bKey['V']) 
    {
        g_matWorld._41 -= 10*elapsetime * vLook.x;
        g_matWorld._42 -= 10*elapsetime * vLook.y;
        g_matWorld._43 -= 10*elapsetime * vLook.z;
    }

    g_pd3dDevice->SetTransform( D3DTS_WORLD, &g_matWorld );
}