graPHIGS Programming Interface: Subroutine Reference

The graPHIGS Programming Interface : Subroutine Reference

GPBRMO - Set Back Reflectance Model

GPBRMO (model)

Purpose

Use GPBRMO to insert a Set Back Reflectance Model structure element into the open structure following the element pointer, or to replace the element pointed at by the element pointer with a Set Reflectance Model structure element, depending on the current edit mode.

This element specifies the lighting reflectance model that the graPHIGS API uses when performing lighting calculations on back facing portions of subsequent area primitives. If the face distinguish mode (GPFDMO) is set to 2=COLOR_SURFACE_PROPERTIES , then the graPHIGS API uses the specified back reflectance model.

The defined back reflectance models and their effect are as follows:

1=REFLECTANCE_NONE

No reflectance calculation is performed.

2=AMB

Ambient reflectance effects are computed.

3=AMB_DIFF

Ambient and diffuse reflectance effects are computed.

4=AMB_DIFF_SPEC

Ambient, diffuse, and specular reflectance effects are computed.

The traversal default for the reflectance model is 1=REFLECTANCE_NONE If the workstation does not support the specified model, then the graPHIGS API uses 1=REFLECTANCE_NONE

Parameters

model -- specified by user, fullword integer

Back reflectance model (1=REFLECTANCE_NONE, 2=AMB, 3=AMB_DIFF, 4=AMB_DIFF_SPEC ).

Error Codes

5: FUNCTION REQUIRES STATE STOP OR NROP (NOT STCL)
110: REFLECTANCE MODEL IS INVALID

Related Subroutines

GPQAAF: Inquire Advanced Attribute Facilities
GPRMO: Set Reflectance Model

RCP code

201343510 (X'0C004216')