Name

peval_view_ori_matrix3 − Provides for 3D translation and rotation of axes. 

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

Syntax

void peval_view_ori_matrix3 (
  const Ppoint3  ∗vrp,        /∗ (I) View reference point, in world
                                     coordinates ∗/
  const Pvec3    ∗vpn,        /∗ (I) View plane normal, in world
                                     coordinates ∗/
  const Pvec3    ∗vup,        /∗ (I) View up vector, in world
                                     coordinates ∗/
  Pint           ∗error_ind,  /∗ (O) Error indicator ∗/
  Pmatrix3        matrix      /∗ (O) View orientation matrix ∗/
)

Data Structures

typedef struct {
    Pfloat     x;    /∗ x coordinate ∗/
    Pfloat     y;    /∗ y coordinate ∗/
    Pfloat     z;    /∗ z coordinate ∗/
} Ppoint3;
typedef struct {
    Pfloat     delta_x;    /∗ delta x value ∗/
    Pfloat     delta_y;    /∗ delta y value ∗/
    Pfloat     delta_z;    /∗ delta z value ∗/
} Pvec3;
typedef Pfloat Pmatrix3[4][4];

Description

peval_view_ori_matrix3 provides for three-dimensional translation and rotation of axes. It returns a view orientation matrix, which can be passed as input to the pset_view_rep3 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

peval_view_map_matrix3
pinq_view_facs
pe_inq_ext_view_rep3
pset_view_ind
pset_view_rep3