SET BACK INTERIOR SHADING METHOD(3P+) — Kubota Pacfic Computer Inc. (29 February 1991)

NAME

SET BACK INTERIOR SHADING METHOD − create a structure element to set the back interior shading method

SYNOPSIS

C Syntax

void
pset_back_int_shade_meth ( method )
Pintmethod;back 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

C Input Parameters

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

1PSD_NONENo Shading
2PSD_COLOURColour Interpolation Shading
3PSD_DOT_PRODUCTDot Product Interpolation Shading
4PSD_NORMALNormal 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 PHIGS 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) will be 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 only to the back facing portion of area defining primitives. See SET FACE DISTINGUISHING MODE (3P+) 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 meth set with SET BACK INTERIOR SHADING METHOD has no effect.

ERRORS

005Ignoring function, function requires state (PHOP, ∗, STOP, ∗)

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