# D3DXMatrixLookAtLH function (D3dx9math.h)

Note

The D3DX utility library is deprecated. We recommend that you use DirectXMath instead.

Builds a left-handed, look-at matrix.

## Syntax

``````D3DXMATRIX* D3DXMatrixLookAtLH(
_Inout_       D3DXMATRIX  *pOut,
_In_    const D3DXVECTOR3 *pEye,
_In_    const D3DXVECTOR3 *pAt,
_In_    const D3DXVECTOR3 *pUp
);
``````

## Parameters

pOut [in, out]

Type: D3DXMATRIX*

Pointer to the D3DXMATRIX structure that is the result of the operation.

pEye [in]

Type: const D3DXVECTOR3*

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

pAt [in]

Type: const D3DXVECTOR3*

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

pUp [in]

Type: const D3DXVECTOR3*

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

## Return value

Type: D3DXMATRIX*

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)  1
``````

## Requirements

Requirement Value