GPHIGS C FUNCTIONS - SET SURFACE APPROXIMATION CRITERIA

SET SURFACE APPROXIMATION CRITERIA

PSET_SURF_APPROX_CRIT

CALL SEQUENCE

void pset_surf_approx_crit (

const Psurf_approx_crit	*data	/* surface approximation criteria data record	*/

TYPES

typedef struct {
	Pint	type;		/* surface approximation type	*/
	union Psurf_approx_crit_data {
		struct Psurf_approx_const_param_subd {
			Pint	u_count;
			Pint	v_count;
		} const_param_subd;
		struct Psurf_approx_chordal_size_wc {
			Pfloat	u_approx;
			Pfloat	v_approx;
		} chordal_size_wc;
		struct Psurf_approx_chordal_size_npc {
			Pfloat	u_approx;
			Pfloat	v_approx;
		} chordal_size_npc;
		struct Psurf_approx_chordal_size_dc {
			Pfloat	u_approx;
			Pfloat	v_approx;
		} chordal_size_dc;
		struct Psurf_approx_planar_dev_wc {
			Pfloat	approx;
		} planar_dev_wc;
		struct Psurf_approx_planar_dev_npc {
			Pfloat	approx;
		} planar_dev_npc;
		struct Psurf_approx_planar_dev_dc {
			Pfloat	approx;
		} planar_dev_dc;
		struct Psurf_approx_rel_wc {
			Pfloat	approx;
		} rel_wc;
		struct Psurf_approx_rel_npc {
			Pfloat	approx;
		} rel_npc;
		struct Psurf_approx_rel_dc {
			Pfloat	approx;
		} rel_dc;
	} data;
} Psurf_approx_crit;

PHIGS STATE

(PHOP,*,STOP,*)

EFFECT

A SET SURFACE APPROXIMATION CRITERIA element is inserted in the open structure after element pointer or replaces the element indicated by element pointer, depending on edit mode. Element pointer then points to the SET SURFACE APPROXIMATION CRITERIA element. The value specified by the parameter is associated with the element.

When an element of this type is interpreted, the current surface approximation criteria entry in the traversal state list is set to the values associated with the element. These values are used when displaying subsequent output primitives when the current surface approximation criteria ASF in the traversal state list is INDIVIDUAL.

Surface approximation criteria types are as follows:

PSURF_APPROX_WS_DEP workstation dependent

PSURF_APPROX_CONST_PARAM_SUBD constant parametric subdivision between knots

PSURF_APPROX_CHORDAL_SIZE_WC chordal size in WC

PSURF_APPROX_CHORDAL_SIZE_NPC chordal size in NPC

PSURF_APPROX_CHORDAL_SIZE_DC chordal size in DC

PSURF_APPROX_PLANAR_DEV_WC planar deviation in WC

PSURF_APPROX_PLANAR_DEV_NPC planar deviation in NPC

PSURF_APPROX_PLANAR_DEV_DC planar deviation in DC

PSURF_APPROX_REL_WC relative in WC

PSURF_APPROX_REL_NPC relative in NPC

PSURF_APPROX_REL_DC relative in DC

When an element of this type is interpreted, if the specified approximation type is not available on a workstation, type PSURF_APPROX_WS_DEP is used.

EXTENSION TO THE PHIGS STANDARD

If GPHIGS is in NRS mode, the effect of this function is different from the effect described in the standard.

In NRS mode, (see OPEN PIPE), the element is not stored in a structure. It is sent to the workstation on which the pipe is opened.

ERRORS

5: Ignoring function, function requires state (PHOP,*, STOP,*)
138: Ignoring function, one or more of the fields in the specified data record is inconsistent with the specified type