cmake_minimum_required(VERSION 2.9) # 指定cmake最小版本

project(learnopengl) # 设置项目名

# 依赖环境
# ------------------------------------------------------------------------------
set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake/modules/")
find_package(GLFW3 REQUIRED)
include_directories(${GLFW3_INCLUDE_DIR})
add_library(glad include/glad.c)
# ------------------------------------------------------------------------------

include_directories(./include) # 添加头文件搜索目录

# 子目录
add_subdirectory(src/start) # 子目录也会有CMakeLists.txt文件，环境是相通的

set( _glfw3_HEADER_SEARCH_DIRS
"/usr/include"
"/usr/local/include"
"${CMAKE_SOURCE_DIR}/includes"
"C:/Program Files (x86)/glfw/include" 
"C:/Program Files (x86)/GLFW/include") # 注意这里，就是我们安装的目录
set( _glfw3_LIB_SEARCH_DIRS
"/usr/lib"
"/usr/local/lib"
"${CMAKE_SOURCE_DIR}/lib"
"C:/Program Files (x86)/glfw/lib-msvc110"
"C:/Program Files (x86)/GLFW/lib") # 注意这里

# Check environment for root search directory
set( _glfw3_ENV_ROOT $ENV{GLFW3_ROOT} )
if( NOT GLFW3_ROOT AND _glfw3_ENV_ROOT )
	set(GLFW3_ROOT ${_glfw3_ENV_ROOT} )
endif()

# Put user specified location at beginning of search
if( GLFW3_ROOT )
	list( INSERT _glfw3_HEADER_SEARCH_DIRS 0 "${GLFW3_ROOT}/include" )
	list( INSERT _glfw3_LIB_SEARCH_DIRS 0 "${GLFW3_ROOT}/lib" )
endif()

# Search for the header
FIND_PATH(GLFW3_INCLUDE_DIR "GLFW/glfw3.h" # 头文件目录的变量
PATHS ${_glfw3_HEADER_SEARCH_DIRS} )

# Search for the library
FIND_LIBRARY(GLFW3_LIBRARY NAMES glfw3 glfw glfw3dll
PATHS ${_glfw3_LIB_SEARCH_DIRS} )
INCLUDE(FindPackageHandleStandardArgs)
FIND_PACKAGE_HANDLE_STANDARD_ARGS(GLFW3 DEFAULT_MSG
GLFW3_LIBRARY GLFW3_INCLUDE_DIR) # 注意这里


IF(GLFW3_FOUND)
	IF(NOT GLFW3_FIND_QUIETLY)
	MESSAGE(STATUS "Found ASSIMP: ${GLFW3_LIBRARY}")
	ENDIF(NOT GLFW3_FIND_QUIETLY)
ELSE(GLFW3_FOUND)
	IF(GLFW3_FIND_REQUIRED)
	MESSAGE(FATAL_ERROR "Could not find GLFW3")
	ENDIF(GLFW3_FIND_REQUIRED)
ENDIF(GLFW3_FOUND)

// 你好，窗口
#include <iostream>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <stdlib.h>


using namespace std;

void framebuffer_size_callback(GLFWwindow* window, int width, int height);

void processInput(GLFWwindow *window);

int main()
{
    cout << "hellow" << endl;
    glfwInit(); // 初始化库
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); // 配置主版本号
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); // 配置次版本号
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // 使用核心模式
    //glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // Mac OS X 使用

    // 创建一个窗口
    GLFWwindow* window = glfwCreateWindow(800, 600, "LearnOpenGL", NULL, NULL);
    if (window == NULL)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window); // 设置为当前上下文

    // glad
    // GLAD是用来管理OpenGL的函数指针的，所以在调用任何OpenGL的函数之前我们需要初始化GLAD。
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

    // 设置窗口的维度
    // glViewport函数前两个参数控制窗口左下角的位置。第三个和第四个参数控制渲染窗口的宽度和高度（像素）。
    glViewport(0, 0, 800, 600);

    // 设置一个回调，当用户改变窗口的大小的时候，视口也应该被调整。
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

    // 渲染循环 render loop
    while(!glfwWindowShouldClose(window))
    {
        processInput(window); // 处理输入

        glClearColor(0.2f, 0.3f, 0.3f, 1.0f); // 设置清空屏幕所用的颜色
        glClear(GL_COLOR_BUFFER_BIT); // 清除颜色缓冲之后，整个颜色缓冲都会被填充为glClearColor里所设置的颜色

        glfwSwapBuffers(window); // 交换颜色缓冲（它是一个储存着GLFW窗口每一个像素颜色值的大缓冲）
        glfwPollEvents(); // 函数检查有没有触发什么事件（比如键盘输入、鼠标移动等）、更新窗口状态，并调用对应的回调函数（可以通过回调方法手动设置）。
    }

    // 释放之前分配的资源
    glfwTerminate();
    return 0;
}

void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
    glViewport(0, 0, width, height);
}

void processInput(GLFWwindow *window)
{
    // 如果按下 esc ， 窗口在下次循环将会退出
    if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);
}

# 你好，窗口
add_executable(HelloWindow HelloWindow.cpp) # 添加可执行程序
target_link_libraries(HelloWindow ${GLFW3_LIBRARY} glad) # 链接lib glfw glad.c