//circle.cpp

#include <cmath>
#include <cstdlib>
#include <format>
#include<glad/glad.h>
#include<GLFW/glfw3.h>
#include <chrono>
#include <iostream>
#include <numbers>
#include <ostream>
#include <stdexcept>
#include <thread>

const float POINT_SIZE = 32.0f;
const unsigned int F_PER_SECOND = 144;
const float PI = 3.141592653589793238462643383279502884L;

typedef  unsigned int u8;

#ifdef NDEBUG
    #define PRINT(v)
#else
    #define PRINT(v){std::cout<<std::format("{} : {}\n",#v,(v));}
#endif


class BouncyBall{
public:
    int bx=0,by=0,bsx=5,bsy=7;
    BouncyBall(int x,int y,int speedX,int speedY):bx(x),by(y),bsx(speedX),bsy(speedY){}
    BouncyBall* update(){
        bx+=bsx,by+=bsy;
        if(bx>=1000||bx<=-1000){
            bsx=-bsx;
        }
        if(by>=1000||by<=-1000){
            bsy=-bsy;
        }
        return this;
    }
};

float angleToRad(float angle){
    return angle/180*PI;
}

void render(){
    glBegin(GL_TRIANGLES);
        static int state  = -1;
        state=(state+1)%F_PER_SECOND;
        const u8 anglePerCircle = 1;
        static float circleSize = 0.1f;
        if(state==0){
            circleSize+=0.1f;
        }
        if(circleSize>1.0f){
            circleSize=0.1f;
        }
        for (u8 i=0;i<u8(float(state)/120.0f*360.0f);i+=anglePerCircle) {
            if(i==0){
                glVertex3f(std::cos(angleToRad(i))*circleSize,std::sin(angleToRad(i))*circleSize,0.0f);
            }else[[likely]]{
                glVertex3f(std::cos(angleToRad(i))*circleSize,std::sin(angleToRad(i))*circleSize,0.0f);
                glVertex3f(std::cos(angleToRad(i))*circleSize,std::sin(angleToRad(i))*circleSize,0.0f);
            }
            glVertex3f(0.0f,0.0f,0.0f);
        }
    glEnd();
}

int main(){
    // 初始化GLFW
    if(glfwInit()==0){
        throw std::runtime_error("failed to init GLFW");
    }
    GLFWwindow *window = glfwCreateWindow(640,640,"Example",nullptr,nullptr);

    if(window==nullptr){
        glfwTerminate();
        throw std::runtime_error("GLFW failed to create window");
    }

    glfwMakeContextCurrent(window);//创建上下文

    if(gladLoadGL()==0){  //加载GL函数
        glfwTerminate();
        throw std::runtime_error("GLAD Load GL functions failed");
    }
    
    std::cout<<"OpenGL version:"<<glGetString(GL_VERSION)<<"\n";

    glEnable(GL_POINT_SMOOTH);
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
    glPointSize(POINT_SIZE);

    while(glfwWindowShouldClose(window)==false){
        glClear(GL_COLOR_BUFFER_BIT);
        render();
        glfwSwapBuffers(window);
        glfwPollEvents();
        std::this_thread::sleep_for(std::chrono::milliseconds(1000/F_PER_SECOND));
    }
    return 0;
}

#ifdef _MSC_VER 
#include<Windows.h>
int WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
    main();
    return 0;
}
#endif