NAME

SET BACK INTERIOR REFLECTANCE EQUATION −  create a structure element to set the current back interior reflectance equation

SYNOPSIS

C Syntax

void
pset_back_refl_eqn ( equation )
Pintequation;back reflectance equation

Required PHIGS Operating States

(PHOP, ∗, STOP, ∗)

DESCRIPTION

Purpose

SET BACK INTERIOR REFLECTANCE EQUATION creates a structure element to set the current back interior reflectance equation. 

When the current back interior reflectance equation 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

• SET OF FILL AREA SET 3 WITH DATA

• NON-UNIFORM B-SPLINE SURFACE

• QUADRILATERAL MESH 3 WITH DATA

• TRIANGLE STRIP 3 WITH DATA

C Input Parameters

equation
The reflectance equation.  The possible values defined in phigs.h are:

1PREFL_NONENo Reflectance Calculation Performed
2PREFL_AMBIENTUse Ambient Term
3PREFL_AMB_DIFFUse Ambient and Diffuse Terms
4PREFL_AMB_DIFF_SPECUse Ambient, Diffuse, and Specular Terms

Execution

Depending on the edit mode, a SET BACK INTERIOR REFLECTANCE EQUATION element with the value reflectance equation 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 REFLECTANCE EQUATION element. 

At traversal time, if the specified reflectance equation is not defined, then the default is used. 

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 (3P+) for details on front and back face determination. 

When the current back interior reflectance equation ASF is set to INDIVIDUAL, area-defining output primitives which follow in the structure network are filled using the current back interior reflectance equation. 

When the current back interior reflectance equation ASF is set to BUNDLED, the back interior reflectance equation is taken from the workstation extended representation indicated by the current interior index.  In this case, the back interior reflectance equation set with SET BACK INTERIOR REFLECTANCE EQUATION has no effect. 

ERRORS

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

SEE ALSO

SET FACE DISTINGUISHING MODE (3P+)
SET INDIVIDUAL ASF (3P)
SET INTERIOR REPRESENTATION PLUS (3P+)
SET REFLECTANCE EQUATION (3P+)
FILL AREA (3P)
FILL AREA 3 (3P)
FILL AREA SET (3P)
FILL AREA SET 3 (3P)
FILL AREA SET 3 WITH DATA (3P+)
SET OF FILL AREA SET 3 WITH DATA (3P+)
NON-UNIFORM B-SPLINE SURFACE (3P+)
QUADRILATERAL MESH 3 WITH DATA (3P+)
TRIANGLE STRIP 3 WITH DATA (3P+)

September 02, 1992