pocketmine\entity\Entity::recalculateEffectColor PHP Method

    protected function recalculateEffectColor()
    {
        $color = [0, 0, 0];
        //RGB
        $count = 0;
        $ambient = true;
        foreach ($this->effects as $effect) {
            if ($effect->isVisible()) {
                $c = $effect->getColor();
                $color[0] += $c[0] * ($effect->getAmplifier() + 1);
                $color[1] += $c[1] * ($effect->getAmplifier() + 1);
                $color[2] += $c[2] * ($effect->getAmplifier() + 1);
                $count += $effect->getAmplifier() + 1;
                if (!$effect->isAmbient()) {
                    $ambient = false;
                }
            }
        }
        if ($count > 0) {
            $r = $color[0] / $count & 0xff;
            $g = $color[1] / $count & 0xff;
            $b = $color[2] / $count & 0xff;
            $this->setDataProperty(Entity::DATA_POTION_COLOR, Entity::DATA_TYPE_INT, ($r << 16) + ($g << 8) + $b);
            $this->setDataProperty(Entity::DATA_POTION_AMBIENT, Entity::DATA_TYPE_BYTE, $ambient ? 1 : 0);
        } else {
            $this->setDataProperty(Entity::DATA_POTION_COLOR, Entity::DATA_TYPE_INT, 0);
            $this->setDataProperty(Entity::DATA_POTION_AMBIENT, Entity::DATA_TYPE_BYTE, 0);
        }
    }