NAME

SET BACK INTERIOR SHADING METHOD - create structure element to set back interior shading method

SYNOPSIS

C Syntax

void

pset_back_int_shad_meth ( method )

Pint

method;

back shading method

FORTRAN Syntax

SUBROUTINE psbism ( METHOD )

INTEGER

METHOD

back interior shading method

Required PHIGS Operating States

(PHOP, * ,STOP, * )

DESCRIPTION

Purpose

SET BACK INTERIOR SHADING METHOD creates a structure element to set the back interior shading method.

When the current back interior shading method ASF is set to INDIVIDUAL, the current value of this attribute applies to the following output primitives:

FILL AREA

FILL AREA 3

FILL AREA SET

FILL AREA SET 3

FILL AREA SET 3 WITH DATA

NON-UNIFORM B-SPLINE SURFACE

SET OF FILL AREA SET 3 WITH DATA

QUADRILATERAL MESH 3 WITH DATA

TRIANGLE STRIP 3 WITH DATA

This is a SunPHIGS Extension function based on PHIGS PLUS and is not part of the PHIGS standard.

C Input Parameter

method The back interior shading method. The predefined values are:

1   PSD_NONE             No Shading
2   PSD_COLOUR           Colour Interpolation Shading
3   PSD_DOT_PRODUCT      Dot Product Interpolation Shading
4   PSD_NORMAL           Normal Interpolation Shading

FORTRAN Input Parameter

The following data types are predefined in phigs77.h.

METHOD

The value of the shading method. The predefined values are:

1   PSDNON     No Shading
2   PSDCOL     Colour Interpolation Shading
3   PSDDOT     Dot Product Interpolation Shading
4   PSDNOR     Normal Interpolation Shading

Execution

Depending on the edit mode, a SET BACK INTERIOR SHADING METHOD element with the value shading method is inserted into the open structure after the element pointer or replaces the element pointed at by the element pointer. The element pointer is then updated to point to this SET BACK INTERIOR SHADING METHOD element.

When the structure is traversed, the current interior shading method entry in the traversal state list is set to the specified value. This value is used with subsequent SunPHIGS Extension output primitives when the current interior shading method ASF entry in the traversal state list is INDIVIDUAL. During traversal, if the specified shading method is not available on a workstation, method one (None) is used on that workstation.

The interior shading method supported by a workstation type can be determined with the function INQUIRE INTERIOR FACILITIES PLUS.

Back face attributes (such as back area properties, back interior colour, back interior reflectance equation, back interior shading method, back interior style, and back interior style index) are used only when the face distinguishing mode has the value Yes and are applied to only the back facing portion of area defining primitives. See SET FACE DISTINGUISHING MODE (3PP) for details on front and back face determination.

When the current back interior shading method ASF is set to INDIVIDUAL, area-defining output primitives, which follow in the structure network and are subject to back face attributes, are filled using the current back interior shading method.

When the current back interior shading method ASF is set to BUNDLED, the back interior shading method is taken from the workstation extended representation indicated by the current interior index. In this case, the back interior shading method set with SET BACK INTERIOR SHADING METHOD has no effect.

SunPHIGS does not support the $ Dot Product Interpolation Shading and $ Normal Interpolation Shading methods.$ When one of these shading methods is specified, $ the backup NONE is used.$

ERRORS

005

Ignoring function, function requires state (PHOP, * ,STOP, * )

SEE ALSO

INQUIRE INTERIOR FACILITIES PLUS (3PP)

SET FACE DISTINGUISHING MODE (3PP)

SET INDIVIDUAL ASF (3P)

SET INTERIOR REPRESENTATION PLUS (3PP)

SET INTERIOR SHADING METHOD (3PP)