GSELNT

GDDM-GKS V1R1 Programming Guide and Reference

GSELNT

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

Purpose


GSELNT	(tnr)

APL code	1353
GKS RCP code	X'38003400' (939537408)

Function: To select normalization transformation.

Transformation function. Selects the current normalization transformation number.

Parameters

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

Operating states

GKOP, WSOP, WSAC, SGOP

Related functions

Set window (GSWN), Set viewport (GSVP), Set clipping indicator (GSCLIP)

Description

This function selects the current normalization transformation number. The current normalization transformation number in the GKS state list is set to the value given by tnr. The clipping rectangle in the GKS state list is set to the viewport limits of the selected normalization transformation.

There are 11 transformation numbers defined, from 0 through 10. Transformation 0 is the unity transformation, which always maps WC (0.0, 1.0) x (0.0, 1.0) to NDC (0.0, 1.0) x (0.0, 1.0); the whole of the world coordinate system maps onto the whole of the NDC coordinate system. Transformations 1 through 10 initially default to be the same as transformation 0, and can be reset to other values with the Set window (GSWN) and Set viewport (GSVP) functions.

Once you have defined the normalization transformations you need, GSELNT lets you choose one of them to be the current one. The current transformation is used to transform subsequent output primitives.

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

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