Add support for building HTML docs with Doxygen v1.8 via CMake.

Author: achalpandeyy

CMakeLists.txt

@@ -180,6 +180,8 @@ option(IRR_BUILD_CEGUI "Enable CEGUI building and integration?" OFF)
 
 option(IRR_BUILD_BULLET "Enable Bullet Physics building and integration?" OFF)
 
+option(IRR_BUILD_DOCS "Enable building documentation?" ON)
+
 set(THIRD_PARTY_SOURCE_DIR "${PROJECT_SOURCE_DIR}/3rdparty")
 
 execute_process(COMMAND git submodule init
@@ -199,3 +201,7 @@ add_subdirectory(ext)
 if(IRR_BUILD_EXAMPLES)
 	add_subdirectory(examples_tests)
 endif()
+
+if(IRR_BUILD_DOCS)
+	add_subdirectory(docs)
+endif()

docs/CMakeLists.txt

@@ -0,0 +1,34 @@
+# Copyright (c) 2019 DevSH Graphics Programming Sp. z O.O.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+find_package(DOXYGEN)
+if(DOXYGEN_FOUND)
+	# Set input and output files
+	set(DOXYGEN_IN ${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.in)
+	set(DOXYGEN_OUT ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)
+
+	# Request to configure the file
+	configure_file(${DOXYGEN_IN} ${DOXYGEN_OUT} @ONLY)
+	message("Doxygen build started")
+
+	# ALL allows the docs to be built together with the application
+	add_custom_target(docs ALL
+	COMMAND ${DOXYGEN_EXECUTABLE} ${DOXYGEN_OUT}
+	WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+	COMMENT "Generating API documentation"
+	VERBATIM)
+else(DOXYGEN_FOUND)
+	message("Doxygen needs to be installed to generate the documentation")
+endif(DOXYGEN_FOUND)