Install this version:
emerge -a =dev-libs/glh-9999
If this version is masked, you can unmask it using the autounmask tool or standard emerge options:
autounmask =dev-libs/glh-9999
Or alternatively:
emerge --autounmask-write -a =dev-libs/glh-9999
# Copyright 1999-2026 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2
EAPI=7
inherit git-r3
EGIT_REPO_URI="https://git.alchemyviewer.org/alchemy/thirdparty/3p-glh_linear.git"
DESCRIPTION="glh - is a platform-indepenedent C++ OpenGL helper library"
HOMEPAGE="https://git.alchemyviewer.org/alchemy/thirdparty/3p-glh_linear"
LICENSE="BSD"
SLOT="0"
KEYWORDS="~amd64 ~x86"
src_install() {
# Install headers
cd "${S}/glh_linear"
insinto /usr/include/GL
doins include/GL/*.h
insinto /usr/include/glh
doins include/glh/*.h
dodoc LICENSES/glh-linear.txt
}