STFPR2/STIPR2/STSPR2

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DCL:GRPH1:STPACK: Transformation Functions:Explanation of Subroutines: Coordinate Transformation

6.3.2 STFPR2/STIPR2/STSPR2

1.

Function

Performs a 2-D perspective transformation.

2.

Call

CALL STFPR2(VX,VY,RX,RY)
CALL STIPR2(RX,RY,VX,VY)
CALL STSPR2(IX,IY,SECT)

3.

Explanation of Arguments

VX,VY (R) The coordinates in VC.

RX,RY (R) The coordinates in RC.

IX,IY (I) Specifies by number which axes in the 3-D space will correspond to the X- and Y-axes in 2-D. (1: X axis; 2: Y axis; 3: Z axis) When a negative value is specified, the axes are inversed.

SECT (R) The coordinates for the point of intersection of the axis and the 2-D plane.

4.

Notes

(a)
The parameters for perspective transformation are common with 3-D perspective transformation.

`VX,VY`	`(R)`	The coordinates in VC.
`RX,RY`	`(R)`	The coordinates in RC.
`IX,IY`	`(I)`	Specifies by number which axes in the 3-D space will correspond to the X- and Y-axes in 2-D. (1: X axis; 2: Y axis; 3: Z axis) When a negative value is specified, the axes are inversed.
`SECT`	`(R)`	The coordinates for the point of intersection of the axis and the 2-D plane.