[obs] implemented intial OBS Looking Glass Client plugin

Yes, it works! but no cursor support yet

obs/CMakeLists.txt

@@ -0,0 +1,72 @@
+cmake_minimum_required(VERSION 3.0)
+project(looking-glass-obs C)
+
+set(CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake/")
+
+include(GNUInstallDirs)
+include(CheckCCompilerFlag)
+include(FeatureSummary)
+
+option(OPTIMIZE_FOR_NATIVE "Build with -march=native" ON)
+if(OPTIMIZE_FOR_NATIVE)
+  CHECK_C_COMPILER_FLAG("-march=native" COMPILER_SUPPORTS_MARCH_NATIVE)
+  if(COMPILER_SUPPORTS_MARCH_NATIVE)
+    add_compile_options("-march=native")
+  endif()
+endif()
+
+option(ENABLE_BACKTRACE "Enable backtrace support on crash" ON)
+add_feature_info(ENABLE_BACKTRACE ENABLE_BACKTRACE "Backtrace support.")
+
+add_compile_options(
+  "-Wall"
+  "-Werror"
+  "-Wfatal-errors"
+  "-ffast-math"
+  "-fdata-sections"
+  "-ffunction-sections"
+  "-fpic"
+  "$<$<CONFIG:DEBUG>:-O0;-g3;-ggdb>"
+)
+
+set(EXE_FLAGS "-Wl,--gc-sections")
+set(CMAKE_C_STANDARD 11)
+
+execute_process(
+	COMMAND			cat ../VERSION
+	WORKING_DIRECTORY	${PROJECT_SOURCE_DIR}
+	OUTPUT_VARIABLE		BUILD_VERSION
+	OUTPUT_STRIP_TRAILING_WHITESPACE
+)
+
+add_definitions(-D BUILD_VERSION='"${BUILD_VERSION}"')
+add_definitions(-D ATOMIC_LOCKING)
+get_filename_component(PROJECT_TOP "${PROJECT_SOURCE_DIR}/.." ABSOLUTE)
+
+include_directories(
+	${PROJECT_SOURCE_DIR}/include
+	${CMAKE_BINARY_DIR}/include
+)
+
+link_libraries(
+	${CMAKE_DL_LIBS}
+	rt
+	m
+)
+
+set(SOURCES
+	main.c
+	lg.c
+)
+
+add_subdirectory("${PROJECT_TOP}/common" "${CMAKE_BINARY_DIR}/common")
+add_subdirectory("${PROJECT_TOP}/LGMP/lgmp" "${CMAKE_BINARY_DIR}/lgmp")
+
+add_library(looking-glass-obs SHARED ${SOURCES})
+target_link_libraries(looking-glass-obs
+	${EXE_FLAGS}
+	lg_common
+	lgmp
+)
+
+feature_summary(WHAT ENABLED_FEATURES DISABLED_FEATURES)