setColorRgbA method
Implementation
void setColorRgbA(PvrtcColorRgb c) {
final r = BitUtility.BITSCALE_8_TO_5_FLOOR[c.r];
final g = BitUtility.BITSCALE_8_TO_5_FLOOR[c.g];
final b = BitUtility.BITSCALE_8_TO_4_FLOOR[c.b];
colorA = r << 9 | g << 4 | b;
colorAIsOpaque = 1;
}