GPTCO - Set Transparency Coefficient

Purpose

Use GPTCO to insert a Set Transparency Coefficient structure element into the open structure following the element pointer, or to replace the element pointed at by the element pointer with a Set Transparency Coefficient structure element, depending upon the current edit mode.

During traversal, the value of coeff specifies the source transparency coefficient of subsequent primitives. The use of the transparency coefficient depends on the Transparency Processing Mode of the view table entry.

If face distinguish mode (GPFDMO) is 1=NONE , then the graPHIGS API uses this value to calculate the transparency effects on both front and back facing portions of area primitives. If face distinguish mode is 2=COLOR_SURFACE_PROPERTIES , then graPHIGS API uses this value to calculate the transparency effects on only front facing portions of area primitives.

The current transparency coefficient in the graPHIGS API Traversal State List is also set by the transparency coefficient of the Set Surface Properties (GPSPR) subroutine.

The traversal default for the transparency coefficient value is 0.0.

Parameters