set_p1_p2(3G)

NAME

set_p1_p2 − set physical device limits

SYNOPSIS

C Syntax:

void set_p1_p2 ( fildes, units, p1_x, p1_y, p1_z, p2_x,
p2_y, p2_z );
int fildes, units;
float p1_x, p1_y, p1_z, p2_x, p2_y, p2_z;

FORTRAN77 Syntax:

subroutine set_p1_p2 ( fildes, units, p1_x, p1_y, p1_z,
p2_x, p2_y, p2_z )
integer*4 fildes, units
real p1_x, p1_y, p2_z, p2_x, p2_y, p2_z

Pascal Syntax:

procedure set_p1_p2 ( fildes, units:integer; p1_x, p1_y, p1_z,
p2_x, p2_y, p2_z:real );

DESCRIPTION

Input Parameters

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

units If set to FRACTIONAL, parameters for P1 and P2 represent decimal fractions of the physical device limits where (0.0, 0.0, 0.0) represents the lower-left-front corner; (1.0, 1.0, 1.0) represents the upper-right-rear corner of the physical display surface. All values of P1 and P2 must range from 0.0 to 1.0, denoting the fraction of the total surface in x or y. Units are anisotropic except in the rare case of a square device.

If set to METRIC, area specification is represented in millimeters. To determine current P1 and P2 in millimeters, use starbase inquire_sizes(3G).

p1_x, p1_y, p1_z Specify P1 (lower-left-front corner) of the region of interest.

p2_x, p2_y, p2_z Specify P2 (upper-right-rear corner) of the region of interest.

Discussion

P1 can be in any position relative to P2, possibly causing mirroring in either or both axes.

This procedure updates the current VDC-to-DC transformation matrix. If no matrices have been placed on the matrix stack and no viewing transformations have been defined, the new device transformation matrix becomes the current viewing transformation. Otherwise no other transformation matrices are affected.

P1 and P2 also define the portion of the display surface to be rendered using hidden surface removal if it is enabled. Set_p1_p2 cannot be called while hidden surface removal is enabled because set_p1_p2 might alter the number of passes required.

Set P1 and P2 before setting related values because changes to P1 and P2 may not affect previously set values such as text size or tracking relationships.

On devices with Z-buffers, the Z-coordinates in set_p1_p2 alter the depth available for hidden surface removal.

DEFAULTS

Units is FRACTIONAL. P1 = (0, 0, 0) and P2 = (1, 1, 1).

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