Name

pe_elliptical_arc − Specifies the 2D, shorthand form of the elliptical arc primitive. 

Operating States: PHOP, ∗, STOP, ∗
Digital PHIGS extension function
Creates a structure element

Syntax

void pe_elliptical_arc (
  const Ppoint  ∗center,       /∗ (I) Center of the elliptical arc, in
                                      modeling coordinates ∗/
  const Pvec    ∗major_axis,   /∗ (I) Vector that defines the x-axis ∗/
  const Pvec    ∗minor_axis,   /∗ (I) Vector that defines the y-axis ∗/
  Pfloat         start_angle,  /∗ (I) Starting angle for drawing the arc,
                                      in radians ∗/
  Pfloat         end_angle     /∗ (I) Ending angle for drawing the arc, in
                                      radians ∗/
)

Data Structures

typedef struct {
    Pfloat     x;    /∗ x coordinate ∗/
    Pfloat     y;    /∗ y coordinate ∗/
} Ppoint;
typedef struct {
    Pfloat     delta_x;    /∗ delta x value ∗/
    Pfloat     delta_y;    /∗ delta y value ∗/
} Pvec;

Description

pe_elliptical_arc specifies the two-dimensional (x and y), shorthand form of the elliptical arc primitive.  The elliptical arc local coordinate system is the xy-plane as defined in the modeling coordinate system.  Digital PHIGS assumes the z-coordinate is 0. 

Depending on the edit mode, this function either inserts the new structure element directly after the element indicated by the pointer or replaces the element indicated by the pointer. The pointer then points to the new elliptical arc element. 

During structure traversal, Digital PHIGS generates an elliptical arc from the start angle to the end angle, in a counterclockwise direction.  Digital PHIGS binds the current values of the polyline primitive, as defined in the PHIGS traversal state list, to the primitive, and renders it according to the current curve approximation criteria. 

If the magnitudes of both axes are less than or equal to 0, Digital PHIGS displays a dot.  If one of the axes is less than or equal to 0, Digital PHIGS displays a line of the correct magnitude.  If the axes do not define the system (the vectors are parallel and nonzero), Digital PHIGS uses (1,0,0) for the major axis and (0,1,0) for the minor axis. 

If Digital PHIGS is in immediate mode, it performs this function immediately, but the function does not create a structure element. 

See Also

padd_names_set
pinq_line_facs
premove_names_set
pset_depth_cue_ind
pset_hlhsr_id
pset_indiv_asf
pset_linetype
pset_linewidth
pset_pick_id
pset_line_colr
pset_line_colr_ind
pset_line_ind
pset_line_shad_method
pset_view_ind