4 files changed, 193 insertions, 0 deletions
diff --git a/dev/snowman/cmake/DownloadHelper.txt.in b/dev/snowman/cmake/DownloadHelper.txt.in
new file mode 100644
index 0000000..fb29bff
--- /dev/null
+++ b/dev/snowman/cmake/DownloadHelper.txt.in
@@ -0,0 +1,26 @@
+# This file is part of the MinGfx cmake build system.  
+# See the main MinGfx/CMakeLists.txt file for authors, copyright, and license info.
+
+# This is a "helper" cmake project -- the only thing this project does is download
+# the external project.  So, the configure, build, install, and test commands for 
+# ExternalProject_Add() are intentionally set as NOPs.  
+
+cmake_minimum_required (VERSION 3.9) 
+
+project(@EXT_PROJECT_NAME@-download)
+
+include(ExternalProject)
+ExternalProject_Add(
+  @EXT_PROJECT_NAME@
+  SOURCE_DIR "@DOWNLOAD_DIR@/@EXT_PROJECT_NAME@/src"
+  BINARY_DIR "@DOWNLOAD_DIR@/@EXT_PROJECT_NAME@/download-helper"
+  @DOWNLOAD_OPTIONS@
+  CONFIGURE_COMMAND ""
+  BUILD_COMMAND ""
+  INSTALL_COMMAND ""
+  TEST_COMMAND ""
+  LOG_DOWNLOAD ON
+  GIT_PROGRESS 1
+)
+
+
diff --git a/dev/snowman/cmake/ExternalProjectDownloadBuildInstall.cmake b/dev/snowman/cmake/ExternalProjectDownloadBuildInstall.cmake
new file mode 100644
index 0000000..ce12d1d
--- /dev/null
+++ b/dev/snowman/cmake/ExternalProjectDownloadBuildInstall.cmake
@@ -0,0 +1,98 @@
+# This file is part of the MinGfx cmake build system.  
+# See the main MinGfx/CMakeLists.txt file for authors, copyright, and license info.
+
+
+# Calling CMAKE_CURRENT_LIST_DIR inside a function returns the list dir of the calling script
+# but we want the list dir of this file in order to find the DownloadHelper.txt.in file, which
+# should be stored right next to this one.  So, defining this variable outside the scope of the
+# functions below.
+set(DIR_OF_THIS_FILE ${CMAKE_CURRENT_LIST_DIR})  
+
+
+
+# Usage:  
+# ExternalProject_Download(
+#     # This first argument is the name of the project to download.  It is required:
+#     glm
+#
+#     # Additional arguments specify how to download the project using GIT, SVN, CVS, or URL.
+#     # These can be any of the arguments used for the downloading step of the cmake builtin
+#     # ExternalProject_Add command. 
+#     GIT_REPOSITORY "https://github.com/g-truc/glm.git"
+#     GIT_TAG master
+#     etc..
+# )
+function(ExternalProject_Download EXT_PROJECT_NAME DOWNLOAD_DIR)
+
+    include(MessageMacros)
+    h1("BEGIN EXTERNAL PROJECT DOWNLOAD (${EXT_PROJECT_NAME}).")
+
+    h2("Creating a download helper project for ${EXT_PROJECT_NAME}.")
+
+    set(DOWNLOAD_OPTIONS ${ARGN})
+    string (REGEX REPLACE "(^|[^\\\\]);" "\\1 " DOWNLOAD_OPTIONS "${DOWNLOAD_OPTIONS}")
+
+
+    file(MAKE_DIRECTORY ${DOWNLOAD_DIR}/${EXT_PROJECT_NAME})
+    configure_file(
+        ${DIR_OF_THIS_FILE}/DownloadHelper.txt.in 
+        ${DOWNLOAD_DIR}/${EXT_PROJECT_NAME}/download-helper/CMakeLists.txt
+    )
+
+    h2("Generating build files for the ${EXT_PROJECT_NAME} download helper project.")
+    execute_process(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" . WORKING_DIRECTORY "${DOWNLOAD_DIR}/${EXT_PROJECT_NAME}/download-helper")
+
+    h2("Building the ${EXT_PROJECT_NAME} download helper project.  (This actually performs the download and may take some time...)")
+    execute_process(COMMAND "${CMAKE_COMMAND}" --build . WORKING_DIRECTORY "${DOWNLOAD_DIR}/${EXT_PROJECT_NAME}/download-helper")
+
+    h2("Completed download of external project ${EXT_PROJECT_NAME}.")
+
+endfunction()
+
+
+# Usage:  
+# ExternalProject_BuildAndInstallNow(
+#     # This first argument is the name of the external project to download.  It is required:
+#     VRPN
+#     # This second argument is the relative path from ${EXTERNAL_DIR_NAME}/projectname/ to the project's
+#     # main CMakeLists.txt file:
+#     src
+#
+#     # Additional arguments are passed on as options to the cmake build file generator
+#     -DVRPN_BUILD_DIRECTSHOW_VIDEO_SERVER=OFF
+#     -DVRPN_BUILD_HID_GUI=OFF
+#     etc..
+# )
+function(ExternalProject_BuildAndInstallNow EXT_PROJECT_NAME DOWNLOAD_DIR RELPATH_TO_CMAKELISTS)
+
+    include(MessageMacros)
+    h1("BEGIN EXTERNAL PROJECT BUILD AND INSTALL (${EXT_PROJECT_NAME}).")
+
+    # any extra args to the function are interpreted as arguments for the cmake config process
+    set(CMAKE_CONFIG_OPTIONS ${ARGN})
+
+    # always set the install prefix to be the same as for the main project
+    list(APPEND CMAKE_CONFIG_OPTIONS -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX})
+
+    #string (REGEX REPLACE "(^|[^\\\\]);" "\\1 " CMAKE_CONFIG_OPTIONS "${CMAKE_CONFIG_OPTIONS}")
+
+
+    set(SRC_DIR "${DOWNLOAD_DIR}/${EXT_PROJECT_NAME}/${RELPATH_TO_CMAKELISTS}")
+    set(BUILD_DIR "${CMAKE_BINARY_DIR}/external/${EXT_PROJECT_NAME}")
+
+    file(MAKE_DIRECTORY ${BUILD_DIR})
+
+    h2("Generating build files for external project ${EXT_PROJECT_NAME}.")
+    message(STATUS "Using source dir: ${SRC_DIR}")
+    message(STATUS "Using build dir: ${BUILD_DIR}")
+    message(STATUS "Config options: ${CMAKE_CONFIG_OPTIONS}")
+
+    execute_process(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" ${SRC_DIR} ${CMAKE_CONFIG_OPTIONS} WORKING_DIRECTORY ${BUILD_DIR})
+
+    h2("Building external project ${EXT_PROJECT_NAME}.  (This may take some time...)")
+    execute_process(COMMAND "${CMAKE_COMMAND}" --build ${BUILD_DIR} --target install)
+
+    h2("Completed external build of ${EXT_PROJECT_NAME}.")
+
+endfunction()
+
diff --git a/dev/snowman/cmake/MessageMacros.cmake b/dev/snowman/cmake/MessageMacros.cmake
new file mode 100644
index 0000000..4628e5c
--- /dev/null
+++ b/dev/snowman/cmake/MessageMacros.cmake
@@ -0,0 +1,17 @@
+# This file is part of the MinVR cmake build system.  
+# See the main MinVR/CMakeLists.txt file for authors, copyright, and license info.
+
+
+macro(h1 TITLE)
+  string(TOUPPER ${TITLE} TITLE)
+  message(STATUS "\n\n==== ${TITLE} ====")
+endmacro()
+
+macro(h2 TITLE)
+  message(STATUS "\n* ${TITLE}")
+endmacro()
+
+macro(h3 TITLE)
+  message(STATUS "- ${TITLE}")
+endmacro()
+
diff --git a/dev/snowman/cmake/UseOpenGL.cmake b/dev/snowman/cmake/UseOpenGL.cmake
new file mode 100644
index 0000000..2ec5ffb
--- /dev/null
+++ b/dev/snowman/cmake/UseOpenGL.cmake
@@ -0,0 +1,52 @@
+# This file is part of the MinGfx cmake build system.  
+# See the main MinGfx/CMakeLists.txt file for authors, copyright, and license info.
+
+# Either finds a pre-installed version or complains.
+
+# Usage: In your CMakeLists.txt, somewhere after you define the target that depends
+# on the OpenGL library (typical with something like add_executable(${PROJECT_NAME} ...) 
+# or add_library(${PROJECT_NAME} ...)), add the following two lines:
+
+#    include(UseOpenGL)
+#    UseOpenGL(${PROJECT_NAME} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/external)
+
+# The second argument can be either PUBLIC, PRIVATE, or INTERFACE, following the keyword
+# usage described here: 
+# https://cmake.org/cmake/help/latest/command/target_include_directories.html
+
+# The third argument is the directory to use for downloading the external project if
+# autobuild is used.
+
+
+
+macro(UseOpenGL YOUR_TARGET INTERFACE_PUBLIC_OR_PRIVATE DOWNLOAD_DIR)
+
+    message(STATUS "Searching for OpenGL...")
+
+	# Check to see if the library is already installed on the system    
+    # CMake ships with FindOpenGL.cmake and in CMake 3.9+ it defines
+    # the imported targets OpenGL::GL and OpenGL::GLU.  Using these is
+    # now the preferred way to link with OpenGL and all of its dependencies.
+	# See https://cmake.org/cmake/help/v3.9/module/FindOpenGL.html
+	find_package(OpenGL)
+
+	if (NOT ${OPENGL_FOUND})
+	    message(FATAL_ERROR "OpenGL was not found on the system.  MinGfx can auto-download and build many dependencies for you, but not OpenGL. It should come pre-installed on your system.")
+	endif()
+
+    message(STATUS "Ok: OpenGL Found.")
+    message(STATUS "OpenGL headers: ${OPENGL_INCLUDE_DIR}")
+    message(STATUS "OpenGL libs: ${OPENGL_LIBRARIES}")
+
+
+    message(STATUS "Linking target ${YOUR_TARGET} with ${INTERFACE_PUBLIC_OR_PRIVATE} dependency OpenGL::GL.")
+    target_link_libraries(${YOUR_TARGET} ${INTERFACE_PUBLIC_OR_PRIVATE} OpenGL::GL)
+
+    if (${OPENGL_GLU_FOUND})
+        message(STATUS "Linking target ${YOUR_TARGET} with ${INTERFACE_PUBLIC_OR_PRIVATE} dependency OpenGL::GLU.")
+        target_link_libraries(${YOUR_TARGET} ${INTERFACE_PUBLIC_OR_PRIVATE} OpenGL::GLU)
+    endif()
+
+	target_compile_definitions(${YOUR_TARGET} ${INTERFACE_PUBLIC_OR_PRIVATE} -DUSE_OPENGL)
+
+endmacro()