GSVP

GDDM-GKS V1R1 Programming Guide and Reference

GSVP

GDDM-GKS V1R1 Programming Guide and Reference
SC33-0334-00

Purpose


GSVP	(tnr, xmin, xmax, ymin, ymax)

APL code	1351
GKS RCP code	X'38003200' (939536896)

Function: To set viewport.

Transformation function. Defines the viewport NDC coordinates for a normalization transformation.

Parameters

tnr (specified by user) (fullword integer)
The transformation number.

xmin (specified by user) (short floating point)

xmax (specified by user) (short floating point)

ymin (specified by user) (short floating point)

ymax (specified by user) (short floating point)
The viewport's limits in normalized device coordinates.

Operating states

GKOP, WSOP, WSAC, SGOP

Related functions

Select normalization transformation (GSELNT), Set window (GSWN), Set viewport input priority (GSVPIP), Inquire normalization transformation (GQNT)

Description

This function defines the dimensions of a normalization transformation viewport. The viewport is the portion of NDC space to which you will map your world coordinate window. The viewport boundaries are limited by the range of NDC coordinates (0.0, 1.0) x (0.0, 1.0). Once selected by the Select normalization transformation (GSELNT) function, the viewport remains in effect until redefined.

GDDM-GKS supports up to 11 transformations. Transformation 0 is the unity transformation, and maps WC (0.0, 1.0) x (0.0, 1.0) to NDC (0.0, 1.0) x (0.0, 1.0). Transformations 1 to 10 default initially to be the same as transformation 0. You can redefine these by calling Set viewport (GSVP) and Set window (GSWN). You can select among the transformations by calling Select normalization transformation (GSELNT).

Principal errors

8: GKS not in proper state: GKS shall be in one of the states GKOP, WSOP, WSAC, or SGOP
50: Transformation number is invalid
51: Rectangle definition is invalid
52: Viewport is not within the Normalized Device Coordinate unit square

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