1.6.2 Settings for Perspective Transformation

In perspective transformation, the parameters that determine transformation function are also specified after calling SGFRM and before drawing graphics. The values of these parameters can be made effective by calling the SCSPRJ routine, which makes the transformation function effective. The parameters for perspective transformation are independent from those of the 2-D and 3-D normalization transformations.

The main parameters are all handled by SGpGET/SGpSET, but the SCPACK routine for setting the parameters at once in also available, and this is normally used for setting the parameters.

To set the parameters for transformation function, the following coding is performed after SGFRM.


  CALL SCSEYE(XEYE3, YEYE3, ZEYE3)

  CALL SCSOBJ(XOBJ3, YOBJ3, ZOBJ3)

  CALL SCSPRJ

All other parameters are specified with SGpSET as necessary.

To allocate a 2-D plane to a 3-D plane,


CALL SCSPLN(IXC3, IYC3, SEC3) 

before SCSPRJ. This will permit the graphics routines on the 2-D planes to be used on a plane in a 3-D space.