$ port rdeps opencv3
The following ports are dependencies of opencv3 @3.4.16_1:
  cmake
    lbzip2
    libcxx
      xz
        gettext
          libiconv
            gperf
          libtextstyle
            ncurses
          gettext-runtime
          gettext-tools-libs
    curl
      pkgconfig
      libidn2
        libunistring
          perl5
            perl5.28
              db48
              gdbm
                readline
          texinfo
            help2man
              perl5.30
              p5.30-locale-gettext
          autoconf
            m4
          automake
          libtool
            xattr
              unzip
      libpsl
        python310
          bzip2
          expat
          libedit
          libffi
            expect
              tcl
            dejagnu
          openssl
            openssl3
              zlib
          sqlite3
          python_select
          python3_select
      zstd
        lz4
      curl-ca-bundle
    libarchive
      libxml2
        icu
      lzo2
      libb2
    libuv
  ffmpeg
    gmake
      lzip
    cctools
    nasm
    lame
    libvorbis
      libogg
    libopus
    librsvg
      rust
        git
          pcre2
          rsync
            popt
            xxhashlib
          p5.28-authen-sasl
            p5.28-digest-hmac
              p5.28-digest-sha1
            p5.28-gssapi
              kerberos5
                python39
                libcomerr
                  coreutils
                    gmp
                lmdb
          p5.28-error
          p5.28-net-smtp-ssl
            p5.28-io-socket-ssl
              p5.28-io-socket-inet6
                p5.28-socket6
                p5.28-io
              p5.28-io-socket-ip
                p5.28-socket
                p5.28-module-build
                  p5.28-cpan-meta-yaml
                  p5.28-cpan-meta
                    p5.28-cpan-meta-requirements
                    p5.28-encode
                    p5.28-scalar-list-utils
                    p5.28-version
                  p5.28-inc-latest
                  p5.28-module-metadata
                  p5.28-perl-ostype
                  p5.28-podlators
                    p5.28-pod-simple
                      p5.28-pod-escapes
              p5.28-mozilla-ca
              p5.28-net-libidn
                libidn
              p5.28-net-ssleay
                p5.28-test-exception
                  p5.28-sub-uplevel
                p5.28-test-nowarnings
                p5.28-test-warn
          p5.28-term-readkey
          p5.28-cgi
            p5.28-test-deep
            p5.28-html-parser
              p5.28-html-tagset
              p5.28-http-message
                p5.28-try-tiny
                  p5.28-capture-tiny
                  p5.28-sub-name
                    p5.28-devel-checkbin
                      p5.28-extutils-makemaker
                        p5.28-extutils-manifest
                p5.28-clone
                  p5.28-b-cow
                p5.28-encode-locale
                p5.28-http-date
                  p5.28-time-local
                  p5.28-timedate
                p5.28-io-html
                p5.28-lwp-mediatypes
                  p5.28-test-fatal
                p5.28-uri
                  p5.28-test-needs
        ninja
          re2c
            bison
              bison-runtime
        libgit2
          libssh2
        openssl11
      cargo
        cargo-bootstrap
      glib2
        meson
          py39-setuptools
            py-bootstrap-modules
        pcre
      cairo
        libpixman
        fontconfig
          freetype
            brotli
            libpng
          ossp-uuid
        xrender
          xorg-libX11
            xorg-xtrans
            xorg-xorgproto
            xorg-util-macros
            xorg-libXdmcp
            xorg-libXau
            xorg-libxcb
              xorg-xcb-proto
              xorg-libpthread-stubs
        xorg-libXext
        xorg-xcb-util
      pango
        gobject-introspection
          autoconf-archive
          gtk-doc
            libxslt
            docbook-xml
              xmlcatmgr
              docbook-xml-4.1.2
                docbook-xml-4.2
              docbook-xml-4.3
              docbook-xml-4.4
              docbook-xml-4.5
              docbook-xml-5.0
            docbook-xsl-nons
            itstool
              gawk
              py310-libxml2
            py39-anytree
              py39-six
                py39-pytest
                  py39-setuptools_scm
                    py39-packaging
                      py39-parsing
                      py39-pretend
                    py39-tomli
                  py39-attrs
                    py39-hypothesis
                      py39-sortedcontainers
                    py39-zopeinterface
                      py39-zope-event
                      py39-pip
                        pip_select
                  py39-iniconfig
                  py39-pluggy
                    py39-py
                  py39-toml
                  pytest_select
              py39-nose
                nosetests_select
            py39-lxml
            py39-pygments
              pygments_select
            py39-mock
          py39-mako
            py39-beaker
            py39-markupsafe
          py39-markdown
        fribidi
        harfbuzz
          graphite2
            py39-fonttools
              fonttools_select
              py39-brotli
              py39-zopfli
                py39-build
                  py39-wheel
                    py39-python-install
                  py39-pep517
              py39-unicodedata2
        Xft2
      gdk-pixbuf2
        shared-mime-info
          xmlto
            getopt
            findutils
            fop
            grep
            gsed
            libpaper
            links
              libevent
        jasper
          libjpeg-turbo
        tiff
      vala
        flex
        graphviz
          webp
            giflib
          gd2
            libheif
              dav1d
              aom
                yasm
              libde265
              rav1e
                cargo-c
              x265
            xpm
              xorg-libXt
                xorg-libsm
                  xorg-libice
          gts
            libnetpbm
          libLASi
          xorg-libXaw
            groff
              ghostscript
                jbig2dec
                openjpeg
                  lcms2
                  jbigkit
              psutils
              netpbm
              uchardet
              urw-fonts
            xorg-libXmu
    libtheora
    libmodplug
    libass
    libbluray
    libvpx
    gnutls
      libtasn1
      p11-kit
      nettle
    zvbi
    speex
    soxr
    zimg
    libsdl2
    XviD
    x264
  ilmbase
  openexr
$