Inside Macintosh: 3D Graphics Programming With QuickDraw 3D /

Chapter 13 - View Objects / View Objects Reference

View Objects Routines / Getting a View's Transforms

Q3View_GetFrustumToWindowMatrixState

You can use the Q3View_GetFrustumToWindowMatrixState function to get a view's frustum-to-window transform matrix.

TQ3Status Q3View_GetFrustumToWindowMatrixState (
TQ3ViewObject view, 
TQ3Matrix4x4 *matrix);

view

A view.

matrix

On exit, a 4-by-4 matrix representing the frustum-to-window transform of the specified view.

DESCRIPTION

The Q3View_GetFrustumToWindowMatrixState function returns, in the matrix parameter, a 4-by-4 matrix that represents the frustum-to-window transform of the view specified by the view parameter. The window is either the pixmap associated with a pixmap draw context or the window associated with a window draw context (for example, the Macintosh draw context). If, in a window system draw context, a part of a window (a pane) has been associated with the view, this function returns the matrix that maps the view frustum to that part of the window.

The z value of a point pw in window space obtained by applying the transform returned by Q3View_GetFrustumToWindowMatrixState to a point pf in the frustum space is the z value of point pf (which ranges from 0.0 to 1.0, inclusive). You might use the z value of a transformed point to determine whether that point would be clipped (if the z value is less than 0 or greater than 1.0, the original point lies outside the viewing frustum).