The Camera - Essentials of Interactive Computer Graphics - page 366

void CGrfxWindowD3D::OnPaint() {
.

Source file.
GrfxWindowD3D.cpp file in
the GrfxWindow folder of the
D3D _ AdjustCamera project.

// Identical to Listing 13.2
.
Step 2: initialize selected hardware and set the coordinate system parameters.
// Set WORLD matrix processor
.
D3DXMATRIX matView;
// camera parameters
D3DXVECTOR3 camera _ pos(...), target _ pos(...), up _ vector(...);
// compute matView
A: D3DXMatrixLookAtRH(&matView,...camera/target/up _ vector...);
// load matView to D3D VIEW processor
m _ pD3DDevice->SetTransform( D3DTS _ VIEW, &matView );
.
// Set PROJECTION matrix processor

Listing 14.1. Details of the VIEW matrix processor settings (Tutorial 14.1).

• Approach. Re-implement Tutorial 13.1 to support slider-bar control of the
camera parameters. In this way, we can adjust the camera parameters and
examine the resulting image.

Figure 14.5 is a screenshot of running Tutorial 14.1. The implementation of this
tutorial is modified from that of Tutorial 13.1 to include GUI slider bars that con-
trol the camera parameters. Listing 14.1 shows the programming code for setting
the camera view. In this case, the camera parameter variables— camera _ pos ,
target _ pos ,and up _ vector —are controlled by the corresponding GUI slider
bars. At label A, these parameters are used for the computation of the matView
matrix, and then the matView matrix is loaded into the D3D VIEW matrix proces-
sor. The mathematical details of the matView matrix will be discussed in Sec-
tion 14.3. Here, we are interested in verifying the effects of the camera parame-
ters. Initially, these parameters are set to those as illustrated in Figure 13.6:

Figure 14.5. Tutorial

14.1.

camera position =( 0 , 10 , − 25 )

look-at position =( 0 , 0 , 0 ) .

up vector =( 0 , 1 , 0 )

The “Reset” button resets all camera parameters to the above default values. The
following discussion assumes the above camera settings.