3D Graphics Programming with QuickDraw 3D 1.5.4

Creating a Camera

The remaining step before you can create a view is to create a camera object. A camera object specifies a point of view and a method of projecting the three-dimensional model into two dimensions. Listing 8 illustrates how to create a camera. See the chapter "Camera Objects" for complete details on the routines called in MyNewCamera .

Listing 8 Creating a camera



 
TQ3CameraObject MyNewCamera (void)

{

    TQ3CameraObject                     myCamera;

    TQ3CameraData                       myCameraData;

    TQ3ViewAngleAspectCameraData        myViewAngleCameraData;

    TQ3Point3D                          cameraFrom = { 0.0, 0.0, 15.0 };

    TQ3Point3D                          cameraTo = { 0.0, 0.0, 0.0 };

    TQ3Vector3D                         cameraUp = { 0.0, 1.0, 0.0 };

    

    /*Fill in camera data.*/

    myCameraData.placement.cameraLocation = cameraFrom;

    myCameraData.placement.pointOfInterest = cameraTo;

    myCameraData.placement.upVector = cameraUp;

    myCameraData.range.hither = .1;

    myCameraData.range.yon = 15.0;

    myCameraData.viewPort.origin.x = -1.0;

    myCameraData.viewPort.origin.y = 1.0;

    myCameraData.viewPort.width = 2.0;

    myCameraData.viewPort.height = 2.0;



    myViewAngleCameraData.cameraData = myCameraData;

    myViewAngleCameraData.fov = Q3Math_DegreesToRadians(100.0);

    myViewAngleCameraData.aspectRatioXToY = 1;



 
    myCamera = Q3ViewAngleAspectCamera_New(&myViewAngleCameraData);

    

    /*Return a camera.*/

    return (myCamera);

}

Like before, the MyNewCamera function simply fills out the fields of the appropriate data structures and calls the Q3ViewAngleAspectCamera_New function to create a new camera object.

All angles in QuickDraw 3D are specified in radians. You can use the Q3Math_DegreesToRadians macro to convert degrees to radians. This is illustrated in Listing 8 , which sets the fov field to 100 degrees.