pset_surf_approx_crit(3g) — Subroutines

Name

pset_surf_approx_crit − Indicates the minimum quality desired for the approximation of the surface’s geometry.

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

Syntax

void pset_surf_approx_crit (
const Psurf_approx_crit ∗data /∗ Surface approximation criteria data
record ∗/
)

Data Structures

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

Constants

Data Structure Constants Constant                   Description
---------------------------------------------------------------------------
Surface approximation     PSURF_APPROX_WS_DEP        Workstation-dependent
types                                                method
                          PSURF_APPROX_CONST_        Constant parametric
                          PARAM_SUBD                 subdivision between
                                                     knots
                          PSURF_APPROX_CHORDAL_      Chordal size, in world
                          SIZE_WC                    coordinate units
                          PSURF_APPROX_CHORDAL_      Chordal size, in
                          SIZE_NPC                   normalized projection
                                                     units
                          PSURF_APPROX_CHORDAL_      Chordal size, in
                          SIZE_DC                    device coordinate
                                                     units
                          PSURF_APPROX_PLANAR_       Planar deviation, in
                          DEV_WC                     world coordinates
                          PSURF_APPROX_PLANAR_       Planar deviation, in
                          DEV_NPC                    normalized projection
                                                     coordinates
                          PSURF_APPROX_PLANAR_       Planar deviation, in
                          DEV_DC                     device coordinates
                          PSURF_APPROX_REL_WC        Relative, in world
                                                     coordinate units
                          PSURF_APPROX_REL_NPC       Relative, in
                                                     normalized projection
                                                     coordinates
                          PSURF_APPROX_REL_DC        Relative, in device
                                                     coordinate units
---------------------------------------------------------------------------

Description

pset_surf_approx_crit indicates the minimum quality desired for the approximation of the surface’s geometry. When you specify two approximation values, the first applies to the u parameter, and the second applies to the v parameter.

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 set surface approximation criteria element.

During structure traversal, if the specified approximation type is undefined, Digital PHIGS uses type 1.

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