Step 2 - Defining the View Transformation Matrix

The view transformation matrix defines the position and rotation of the view. The view matrix is the camera for the scene.

The following code fragment creates the view transformation matrix and then sets the current view transformation for the Direct3D device.

D3DXVECTOR3 vEyePt   ( 0.0f, 3.0f,-5.0f );
D3DXVECTOR3 vLookatPt( 0.0f, 0.0f, 0.0f );
D3DXVECTOR3 vUpVec   ( 0.0f, 1.0f, 0.0f );
D3DXMATRIXA16 matView;
D3DXMatrixLookAtLH( &matView, &vEyePt, &vLookatPt, &vUpVec );
g_pd3dDevice->SetTransform( D3DTS_VIEW, &matView );

The first step is to define the view matrix by calling D3DXMatrixLookAtLH. The first parameter is a pointer to a D3DXMATRIX structure that is the result of the operation. The second, third, and fourth parameters define the eye point, look-at point, and "up" direction, respectively. Here the eye is set back along the z-axis by five units and up three units, the look-at point is set at the origin, and "up" is defined as the y-direction.

The next step is to call IDirect3DDevice9::SetTransform to set the view transformation for the Direct3D device. The first parameter accepted by IDirect3DDevice9::SetTransform tells Direct3D which transformation to set. This sample uses the D3DTS_VIEW flag to specify that the view transformation should be set. The second parameter is a pointer to a matrix that is set as the current transformation.

For more information about view transformations, see View Transform.

After defining the world transformation for the scene, you can prepare the projection transformation matrix. Again, note that the order in which transformations are defined is not critical. However, Direct3D applies the matrices to the scene in the following order:

1. World
2. View
3. Projection

Defining the projection transformation matrix is described in Step 3 - Defining the Projection Transformation Matrix.