POLYTYPE_GCOL (3) Linux Manual Page
POLYTYPE_GCOL – Polygon rendering mode type Allegro game programming library.
Synopsis
#include <allegro.h>
#define POLYTYPE_GCOL
Description
A single-color gouraud shaded polygon. The colors for each vertex are taken from the `c’ value, and interpolated across the polygon. This is very fast, but will only work in 256-color modes if your palette contains a smooth gradient between the colors. In truecolor modes it interprets the color as a packed, display-format value as produced by the makecol() function.