Drill into View Matrix

How does DirectX build the view matrix - From MSDN

D3DXMatrixLookAtLH

Builds a left-handed, look-at matrix.

D3DXMATRIX * D3DXMatrixLookAtLH(
  D3DXMATRIX * pOut,
  CONST D3DXVECTOR3 * pEye,
  CONST D3DXVECTOR3 * pAt,
  CONST D3DXVECTOR3 * pUp
);

Parameters

pOut

[in, out] Pointer to the D3DXMATRIX structure that is the result of the operation.

pEye

[in] Pointer to the D3DXVECTOR3 structure that defines the eye point. This value is used in translation.

pAt

[in] Pointer to the D3DXVECTOR3 structure that defines the camera look-at target.

pUp

[in] Pointer to the D3DXVECTOR3 structure that defines the current world's up, usually [0, 1, 0].

Return Values

Pointer to a D3DXMATRIX structure that is a left-handed, look-at matrix.

Remarks

The return value for this function is the same value returned in the pOut parameter. In this way, the D3DXMatrixLookAtLH function can be used as a parameter for another function.

 

This function uses the following formula to compute the returned matrix.

zaxis = normal(At - Eye)
xaxis = normal(cross(Up, zaxis))
yaxis = cross(zaxis, xaxis)
    
 xaxis.x           yaxis.x           zaxis.x          0
 xaxis.y           yaxis.y           zaxis.y          0
 xaxis.z           yaxis.z           zaxis.z          0
-dot(xaxis, eye)  -dot(yaxis, eye)  -dot(zaxis, eye)  l

// insert material here: Introduction to 3D game programing with DirectX 9.0C

// Chapter 12-2 Implementation details

the eye point is uaually the equivalent to camera position