Add: Support sound effects in Ogg Opus format.

cmake/FindOpus.cmake

@@ -0,0 +1,37 @@
+include(FindPackageHandleStandardArgs)
+
+find_library(Opus_LIBRARY
+    NAMES opus
+)
+
+set(Opus_COMPILE_OPTIONS "" CACHE STRING "Extra compile options of opus")
+
+set(Opus_LINK_LIBRARIES "" CACHE STRING "Extra link libraries of opus")
+
+set(Opus_LINK_FLAGS "" CACHE STRING "Extra link flags of opus")
+
+find_path(Opus_INCLUDE_PATH
+    NAMES opus.h
+    PATH_SUFFIXES opus
+)
+
+find_package_handle_standard_args(Opus
+    REQUIRED_VARS Opus_LIBRARY Opus_INCLUDE_PATH
+)
+
+if (Opus_FOUND)
+    set(Opus_dirs ${Opus_INCLUDE_PATH})
+    if(EXISTS "${Opus_INCLUDE_PATH}/opus")
+        list(APPEND Opus_dirs "${Opus_INCLUDE_PATH}/opus")
+    endif()
+    if (NOT TARGET Opus::opus)
+        add_library(Opus::opus UNKNOWN IMPORTED)
+        set_target_properties(Opus::opus PROPERTIES
+            IMPORTED_LOCATION "${Opus_LIBRARY}"
+            INTERFACE_INCLUDE_DIRECTORIES "${Opus_dirs}"
+            INTERFACE_COMPILE_OPTIONS "${Opus_COMPILE_OPTIONS}"
+            INTERFACE_LINK_LIBRARIES "${Opus_LINK_LIBRARIES}"
+            INTERFACE_LINK_FLAGS "${Opus_LINK_FLAGS}"
+        )
+    endif()
+endif()