Remove CPU rendering support for Ubuntu 18.04 (old mesa SW)

Update docs.

3rdparty/find_dependencies.cmake

@@ -1405,24 +1405,6 @@ else()
 endif()
 list(APPEND Open3D_3RDPARTY_HEADER_TARGETS_FROM_SYSTEM Open3D::3rdparty_opengl)
 
-# CPU Rendering
-if(BUILD_GUI AND UNIX AND NOT APPLE)
-    include(FetchContent)
-    FetchContent_Declare(
-        download_mesa_libgl
-        PREFIX mesa
-        URL https://github.com/isl-org/open3d_downloads/releases/download/mesa-libgl/mesa_libGL_22.1.4.tar.bz2
-        URL_HASH SHA256=5732bfb70e8fcc747018820bc8fd31cd1867ebae5aa09baf65482b42c134d45a
-        DOWNLOAD_DIR "${OPEN3D_THIRD_PARTY_DOWNLOAD_DIR}/mesa"
-        )
-    FetchContent_MakeAvailable(download_mesa_libgl)
-
-    set(MESA_CPU_GL_LIBRARY "${download_mesa_libgl_SOURCE_DIR}/libGL.so.1.2.0" "${download_mesa_libgl_SOURCE_DIR}/libEGL.so.1.0.0"
-        "${download_mesa_libgl_SOURCE_DIR}/libgallium_dri.so" "${download_mesa_libgl_SOURCE_DIR}/kms_swrast_dri.so"
-        "${download_mesa_libgl_SOURCE_DIR}/swrast_dri.so")
-    message(STATUS "MESA_CPU_GL_LIBRARY: ${MESA_CPU_GL_LIBRARY}")
-endif()
-
 # RPC interface
 # zeromq
 if(USE_SYSTEM_ZEROMQ)

cpp/pybind/CMakeLists.txt

@@ -84,8 +84,7 @@ set_target_properties(pybind PROPERTIES
 # libc++.so is a linker script including libc++.so.1 and libc++abi.so, so append 1 to libc++.so
 set(PYTHON_EXTRA_LIBRARIES "")
 if (BUILD_GUI AND CMAKE_SYSTEM_NAME STREQUAL "Linux")
-    list(APPEND PYTHON_EXTRA_LIBRARIES ${CPP_LIBRARY}.1 ${CPPABI_LIBRARY}
-        ${MESA_CPU_GL_LIBRARY})
+    list(APPEND PYTHON_EXTRA_LIBRARIES ${CPP_LIBRARY}.1 ${CPPABI_LIBRARY})
 endif()
 if (WITH_OPENMP AND APPLE AND NOT BUILD_SHARED_LIBS)
 # Package libomp v11.1.0, if it is not installed. Later version cause crash on

docs/tutorial/visualization/cpu_rendering.rst

@@ -31,28 +31,23 @@ the :class: `.OffscreenRenderer` for a process by setting an environment
 variable  before importing Open3D::
 
  - ``EGL_PLATFORM=surfaceless`` for Ubuntu 20.04+ (Mesa v20.2 or newer)
- - ``OPEN3D_CPU_RENDERING=true`` for Ubuntu 18.04 (Mesa older than v20.2).
 
 Here are the different ways to do that:
 
 .. code:: bash
 
     # from the command line (Ubuntu 20.04+)
     EGL_PLATFORM=surfaceless python examples/python/visualization/render_to_image.py
-    # or Ubuntu 18.04
-    OPEN3D_CPU_RENDERING=true python examples/python/visualization/render_to_image.py
 
 .. code:: python
 
     # In Python code
     import os
     os.environ['EGL_PLATFORM'] = 'surfaceless'   # Ubuntu 20.04+
-    os.environ['OPEN3D_CPU_RENDERING'] = 'true'  # Ubuntu 18.04
     import open3d as o3d
 
     # In a Jupyter notebook
     %env EGL_PLATFORM surfaceless   # Ubuntu 20.04+
-    %env OPEN3D_CPU_RENDERING true  # Ubuntu 18.04
     import open3d as o3d
 
 .. note:: Setting the environment variable after importing ``open3d`` will not work,
@@ -106,30 +101,4 @@ The method for enabling interactive CPU rendering depends on your system:
     .. code:: bash
 
         export LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libGLX_mesa.so.0
-        python examples/python/visualization/draw.py
-
-3.  **Your OS has old Mesa drivers (< v20.2).**  We provide
-    the Mesa software rendering library binary for download `here
-    <https://github.com/isl-org/open3d_downloads/releases/download/mesa-libgl/mesa_libGL_22.0.tar.xz>`__.
-    This is automatically downloaded to
-    `build/_deps/download_mesa_libgl-src/libGL.so.1.5.0` when you build Open3D
-    from source. The prebuilt version works on Ubuntu 18.04 and Ubuntu 20.04. If
-    you want to use CPU rendering all the time, install this library to
-    ``/usr/local/lib`` or ``$HOME/.local/lib`` and *prepend* it to your
-    ``LD_LIBRARY_PATH``:
-
-    .. code:: bash
-
-        export LD_LIBRARY_PATH=$HOME/.local/lib:$LD_LIBRARY_PATH
-
-    For occasional use, you can instead launch a program with CPU rendering with:
-
-    .. code:: bash
-
-        LD_PRELOAD=$HOME/.local/lib/libGL.so.1.5.0 Open3D
-
-    Or with Python code:
-
-    .. code:: bash
-
-        LD_PRELOAD=$HOME/.local/lib/libGL.so.1.5.0 python examples/python/visualization/draw.py
+        python examples/python/visualization/draw.py

python/open3d/__init__.py

@@ -46,13 +46,6 @@ def load_cdll(path):
     except StopIteration:  # Not found: check system paths while loading
         pass
 
-# Enable CPU rendering based on env vars
-if _build_config["BUILD_GUI"] and sys.platform.startswith("linux") and (
-        os.getenv("OPEN3D_CPU_RENDERING", default="") == "true"):
-    os.environ["LIBGL_DRIVERS_PATH"] = str(Path(__file__).parent)
-    load_cdll(Path(__file__).parent / "libEGL.so.1")
-    load_cdll(Path(__file__).parent / "libGL.so.1")
-
 __DEVICE_API__ = "cpu"
 if _build_config["BUILD_CUDA_MODULE"]:
     # Load CPU pybind dll gracefully without introducing new python variable.