GSWN

GDDM-GKS V1R1 Programming Guide and Reference

GSWN

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

Purpose


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

APL code	1350
GKS RCP code	X'38003100' (939536640)

Function: To set window.

Transformation function. Defines the world coordinate window 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 window limits in world coordinates.

Operating states

GKOP, WSOP, WSAC, SGOP

Related functions

Select normalization transformation (GSELNT), Set viewport (GSVP), Set viewport input priority (GSVPIP), Inquire normalization transformation (GQNT), Set clipping indicator (GSCLIP)

Description

This function defines the world coordinate window for the normalization transformation tnr. The window limits given by the other parameters are stored in the entry for the transformation in the GKS state list.

When you use output primitives or geometric attributes, you specify positions and dimensions in world coordinates (WC). You can make up a picture from separate parts, each of which is defined in its own world coordinates. You control the relative positioning of the separate parts by defining normalization transformations, which map each part into a single coordinate system - normalized device coordinate space (NDC). The normalization transformation window and viewport determine the transformation used to transform WC into NDC. Window and viewport limits specify rectangles parallel to the coordinate axes in WC and NDC. The normalization transformation maps the entire window to the entire viewport, performing any scaling required, separately, for the x and y axes. Coordinates outside the window of the current normalization transformation are also transformed. If clipping is on, primitives are clipped to the viewport after any segment transformations have been applied.

GDDM-GKS supports up to 11 normalization 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

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