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The graPHIGS Programming Interface: ISO PHIGS Subroutine Reference

EVALUATE VIEW MAPPING MATRIX (PHOP,*,*,*)

Purpose

Use Evaluate View Mapping Matrix to create a two-dimensional view mapping matrix. Your application can use the matrix as input to the Set View Representation subroutine.

When calculating the view mapping matrix, the graPHIGS API:

  • sets the z extents for the viewport to the z extents of the Normalized Projection Coordinates (NPC) range.

  • sets the projection type to PARALLEL.

  • places the projection reference point on a line perpendicular to the center of the specified window.

  • sets the z value of the projection reference point to one-half of the maximum of the Umax-Umin and Vmax-Vmin.

  • sets the view plane distance to zero.

  • sets the far clipping plane to the negative of one-half of the maximum of the Umax-Umin and Vmax-Vmin.

  • sets the near clipping plane to one-half of the maximum of the Umax-Umin and Vmax-Vmin.

    If the graPHIGS API can compute the view mapping matrix, then the graPHIGS API sets the error indicator to zero and returns the view mapping matrix. If the graPHIGS API cannot compute the view mapping matrix, then the values of the matrix are unpredictable and the graPHIGS API sets the error indicator to one of the following errors:

    2
    Function Requires State (PHOP,*,*,*)
    151
    Invalid Window: Minimum Value >= To Corresponding Maximum Value
    152
    Invalid Viewport: XMIN >= XMAX, YMIN >= YMAX OR ZMIN > ZMAX
    155
    Projection Viewport Limits Are Not Within NPC Range

    Language Bindings

    • C

    peval_view_map_matrix (mapping, err_ind, result_tran)

    Input Parameters

    const Pview_map *mapping
    View mapping (window limits in VC and projection viewport limits in NPC).

    Output Parameters

    Pint *err_ind
    Error indicator.

    Pmatrix result_tran
    View mapping matrix. (See Chapter 15. "ISO PHIGS Transformations" for a description of the storage of the transformation matrix).

    FORTRAN

    PEVMM (vwwnlm, pjvplm, errind, vwmpmt)

    Input Parameters

    real vwwnlm(4)
    Window limits in VC (UMIN, UMAX, VMIN, VMAX).

    real pjvplm(4)
    Projection viewport limits in NPC (XMIN, XMAX, YMIN, YMAX).

    Output Parameters

    integer errind
    Error indicator.

    real vwmpmt(3,3)
    View mapping matrix. (See Chapter 15. "ISO PHIGS Transformations" for a description of the storage of the transformation matrix).

    Errors

    None

    Related Subroutines

  • None

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