Provides pre-compiled static 'VTK' libraries and headers so that downstream R packages can link against the Visualization Toolkit without requiring users to install 'VTK' manually. On all platforms the package first honours a user-supplied 'VTK_DIR' environment variable. On macOS it then tries 'Homebrew', followed by 'pkg-config'. On Linux it tries 'pkg-config' and well-known system prefixes ('/usr', '/usr/local'). If no suitable system installation is found on macOS or Linux, pre-built static libraries are downloaded automatically from the package's GitHub releases. On Windows the package tries 'VTK_DIR', then 'Rtools45' 'pacman', then common 'MSYS2' prefixes, accepting both static ('.a') and shared ('.dll.a' import libs + DLLs) installations. When shared libraries are used, the VTK DLLs are staged in 'inst/vtk-dlls/' and an '.onLoad' hook prepends that directory to PATH via 'Sys.setenv()' when the package is loaded, and restored in '.onUnload()'. The pre-built fallback downloads static libraries by default; set 'VTK_LINK_TYPE=shared' before installation to download the DLL build instead. Note that on Windows the modules 'VTK_IONetCDF', 'VTK_IOHDF', 'VTK_GeovisCore', and 'VTK_RenderingCore' are disabled because 'netcdf' and 'libproj' are not available in the 'Rtools45' 'static.posix' sysroot. Downstream packages can declare 'Imports: rvtk' and obtain the correct compiler and linker flags at install time via rvtk::CppFlags() and rvtk::LdFlagsFile().