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GSX-86: Graphics for the APC
9-10
INPUT POINT COORDINATE ARRAY
The input point coordinate array contains the following values when the function is
called.
ptsin
Array of input coordinates. Each point is specified
by an X,Y coordinate pair given in Normalized
Device Coordinates (0-32,767 with length
control(2)
*
2).
OUTPUT CONTROL ARRAY
The output control array contains the following values when the function is
completed.
control (3)
control (5)
control
(6-n)
Number of vertices in output point array (ptsout)
Length of input parameter array
Opcode-dependent
OUTPUT PARAMETER ARRAY
The output parameter array contains the following values when the function is
called.
intout
Array of output parameters. Length of array is opcode-
dependent.
OUTPUT POINT COORDINATE ARRAY
The output point coordinate array contains the following values when the function
is called.
ptsout
Array of output coordinates. Each point is specified by an
X, Y coordinate pair given in Normalized Device Coordi-
nates (0-32,767) and must be greater than the largest possi-
ble value of control (5)
*
2.
Normalized Device Coordinates
The application program passes all graphics coordinates to G DOS as Normalized
Device Coordinates (NDC) in a range from 0 to 32,767 along each axis. These units
are mapped to the actual device units (e.g. rasters for CRTs or steps for plotters/-
printers) using information passed from the device driver when the workstation was
opened by GSX-86 so that all coordinates passed to the device driver are in device
units.
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