# 版本要求
cmake_minimum_required(VERSION 3.31)

# 项目名称和语言
project(opengl_homework LANGUAGES CXX)

# C++ 标准
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED True)

# 自动运行 MOC, UIC, RCC (如果使用 Qt，这里不需要)
#set(CMAKE_AUTOMOC ON)
#set(CMAKE_AUTOUIC ON)
#set(CMAKE_AUTORCC ON)

# 包含目录
include_directories(include)

# GLEW: 作为静态库链接或动态库
# 查找GLEW
find_package(GLEW REQUIRED)
if (GLEW_FOUND)
    include_directories(${GLEW_INCLUDE_DIRS})
    message(STATUS "Found GLEW: ${GLEW_LIBRARIES}")
else ()
    message(FATAL_ERROR "GLEW not found")
endif ()

# 查找OpenGL
find_package(OpenGL REQUIRED)
if (OPENGL_FOUND)
    include_directories(${OPENGL_INCLUDE_DIR})
    message(STATUS "Found OpenGL: ${OPENGL_gl_LIBRARY}")
else ()
    message(FATAL_ERROR "OpenGL not found")
endif ()

# 查找GLUT
find_package(GLUT REQUIRED)
if (GLUT_FOUND)
    include_directories(${GLUT_INCLUDE_DIR})
    message(STATUS "Found GLUT: ${GLUT_glut_LIBRARY}")
else ()
    message(FATAL_ERROR "GLUT not found")
endif ()

# GLM (OpenGL Mathematics Library)
# 尝试查找系统安装的GLM
find_package(glm QUIET)
if (NOT glm_FOUND)
    message(STATUS "glm not found. Fetching from source...")
    include(FetchContent)
    FetchContent_Declare(
            glm
            GIT_REPOSITORY https://github.com/g-truc/glm.git
            GIT_TAG 0.9.9.8 # 你可以选择一个具体的tag或者分支
    )
    FetchContent_MakeAvailable(glm)
    # 对于FetchContent下载的glm，其include目录通常是 ${glm_SOURCE_DIR}
    # 对于一些版本的CMake/glm，可能是 ${glm_SOURCE_DIR}/glm
    # 为了保险起见，可以都添加，或者根据实际下载的结构调整
    include_directories(${glm_SOURCE_DIR})
    message(STATUS "Fetched glm and added include directory: ${glm_SOURCE_DIR}")
else ()
    message(STATUS "Found system-installed glm: ${glm_INCLUDE_DIR}")
    include_directories(${glm_INCLUDE_DIR})
endif ()


# 创建 shaders 目录的引用，方便在代码中加载 (可选)
# set(SHADER_DIR ${CMAKE_CURRENT_SOURCE_DIR}/shaders)

# 添加可执行文件
add_executable(OpenGLProject
        main.cpp
        shader_utils.cpp
)

# 链接库
target_link_libraries(OpenGLProject
        PRIVATE
        ${OPENGL_LIBRARIES}
        ${GLEW_LIBRARIES}
        ${GLUT_glut_LIBRARY}
)

# 如果GLEW是作为静态库链接的，可能需要定义GLEW_STATIC
# target_compile_definitions(OpenGLProject PRIVATE GLEW_STATIC)

# 为了确保着色器文件能被程序找到，可以将它们复制到构建目录
# 或者在代码中指定相对或绝对路径
# 这里我们假设着色器文件和可执行文件在同一目录下运行，或者代码中处理路径
# 如果着色器在 "shaders" 子目录中:
set(SHADER_FILES
        shaders/phong.vert
        shaders/phong.frag
)

# 将着色器文件复制到可执行文件旁边
foreach (SHADER_FILE ${SHADER_FILES})
    add_custom_command(
            TARGET OpenGLProject POST_BUILD
            COMMAND ${CMAKE_COMMAND} -E make_directory $<TARGET_FILE_DIR:OpenGLProject>/shaders
            COMMAND ${CMAKE_COMMAND} -E copy_if_different
            ${CMAKE_CURRENT_SOURCE_DIR}/${SHADER_FILE}
            $<TARGET_FILE_DIR:OpenGLProject>/shaders/
            COMMENT "Copying shader ${SHADER_FILE} to build directory"
    )
endforeach ()

# 创建目标 shaders 目录
add_custom_command(
        TARGET OpenGLProject POST_BUILD
        COMMAND ${CMAKE_COMMAND} -E make_directory $<TARGET_FILE_DIR:OpenGLProject>/shaders
        COMMENT "Creating shaders directory in build output"
)