Name

PEVOM3 − Provides for 3D translation and rotation of axes. 

Operating States: PHOP, ∗, ∗, ∗
PHIGS standard function
 

Syntax

PEVOM3 (VWRX, VWRY, VWRZ, VPNX, VPNY, VPNZ, VUPX, VUPY, VUPZ, ERRIND,
VWORMT)

Argument     Data Type        Access    Description
---------------------------------------------------------------------------
VWRX, VWRY   Real             Read      View reference point, in world
VWRZ                                    coordinates
VPNX, VPNY   Real             Read      View reference normal, in world
VPNZ                                    coordinates
VUPX, VUPY   Real             Read      View up vector, in world
VUPZ                                    coordinates
ERRIND       Integer          Write     Error indicator
VWORMT(4,4)  Array of reals   Write     View orientation matrix
---------------------------------------------------------------------------

Description

PEVOM3 provides for three-dimensional translation and rotation of axes. It returns a view orientation matrix, which can be passed as input to the PSVWR3 function.  The view orientation matrix in the view representation transforms the PHIGS coordinate system from world coordinate points to view reference coordinate points. 

The specified view reference point is a three-dimensional point that defines a point in the world coordinate plane.  This point becomes the origin of the view reference coordinate system.  (See Getting Started with DEC PHIGS for information about the view reference coordinate system.) 

The specified view plane normal is a three-dimensional vector relative to the view reference point.  It defines the n-axis of the view reference coordinate system, which is the third axis of the system.  The view reference plane is the plane in world coordinate space that contains the view reference point and is perpendicular to the view plane normal. 

The specified view up vector is a three-dimensional vector relative to the view reference point.  It is projected onto the view reference plane through a projection parallel to the view plane normal.  The projection of the view up vector onto the view reference plane determines the v-axis of the view reference coordinate system. 

The following restrictions apply to the specified values:

•The view up vector and view plane normal are not parallel, so that the view coordinates can be established. 

•The length of the view up vector is greater than 0. 

•The length of the view plane normal is greater than 0. 

If the view orientation parameters are consistent and well defined (that is, if they conform to the specified rules and restrictions), a call to this function returns the three-dimensional (4x4) view orientation matrix.  Otherwise, the function returns a nonzero error indicator. 

See Also

PEVMM3
PQVWF
PQVWR
PSVWI
PSVWR3