Name

PEVOM − Provides for 2D translation and rotation in the xy-plane of the world coordinate system. 

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

Syntax

PEVOM (VWRX, VWRY, VUPX, VUPY, ERRIND, VWORMT)

Argument     Data Type        Access    Description
---------------------------------------------------------------------------
VWRX, VWRY   Real             Read      View reference point, in world
                                        coordinates
VUPX, VUPY   Real             Read      View up vector, in world
                                        coordinates
ERRIND       Integer          Write     Error indicator
VWORMT(3,3)  Array of reals   Write     View orientation matrix
---------------------------------------------------------------------------

Description

PEVOM provides for two-dimensional translation and rotation in the xy-plane of the world coordinate system. It returns a two-dimensional (3 x 3) view orientation matrix, which can be passed as input to the PSVWR 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 two-dimensional point that defines a point in world coordinate units, where z is 0.  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 up vector is a two-dimensional vector relative to the view reference point.  It indicates a direction in the world coordinate plane, where z is set to 0 by default.  This direction becomes the v-axis of the view reference coordinate system.  (The n-axis of the view reference coordinate system is parallel to the z-axis of the world coordinate system.  The u-axis of the view reference coordinate system is determined such that the uvn-axes form a right-handed coordinate system.) 

The PEVOM function is a shorthand way of calling PEVOM3, where the following rules apply:
 

•The z-coordinate on the view reference point is 0. 

•The view plane normal is set to [0,0,1]. 

•The z-coordinate of the view up vector is 0. 

•The third row and third column of the resulting 4 x 4 matrix is suppressed. 

The view up vector must have a length 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 3 x 3 view orientation matrix.  Otherwise, a nonzero error indicator is returned. 

See Also

PEVMM
PQVWF
PQVWR
PSVWI
PSVWR