NAME

zbuffer_switch  − enable section of display surface for zbuffer hidden surface removal

SYNOPSIS

C Syntax:

void zbuffer_switch(fildes,pass);
int fildes,pass;

FORTRAN77 Syntax:

subroutine zbuffer_switch(fildes,pass)
integer *4 fildes,pass

Pascal Syntax:

procedure zbuffer_switch(fildes,pass:integer);

DESCRIPTION

Input Parameters

fildes Integer file descriptor  returned by gopen when an I/O path to a graphics device is opened. 

pass Number specifying which pass of the user data is to be expected. 

Discussion

If multiple passes of the user data are needed to do complete hidden surface removal, the frame buffer is divided into vertical strips and rendered one at a time.  The number of strips is determined by the hidden_surface procedure.  When this procedure is called, the zbuffer is cleared and the clip limits are set to the intersection of the current clip rectangle and the rectangle defining the requested strip of frame buffer as defined by the pass parameter. Pass 1 renders the left-most strip and subsequent passes render strips left to right.  This procedure should be called even when multiple passes are not necessary in order to clear out the zbuffer.  This is usually done whenever clear_view_surface or dbuffer_switch is called. 

DEFAULTS

pass 1 is expected. 

SEE ALSO

hidden_surface(3G),
Starbase Graphics Techniques.

Hewlett-Packard Company  —  May 11, 2021