#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <graphics.h>

/*
	复习：结构体、循环、函数、数组、eaxyx
	eaxyx：图形界面库
*/
//做界面1，创建一个图形界面窗口
//🐍的方向
//🐍的速度
//🐍的结构
#define SNAKE_NUM 500  //蛇的最大节数

enum DIR            //表示🐍的方向
{
	UP,
	DOWN,
	LEFT,
	RIGHT,
};

struct Snake
{
	int size;      //🐍的节数
	int dir;       //🐍的方向
	int speed;     //🐍的速度
	POINT coor[SNAKE_NUM];  //坐标
}snake; 

//数据的初始化
void GameInit()
{
	//init  初始化  graph  图形化窗口    SHOWCONSOLE  显示控制台
	initgraph(640, 480);
	//初始化🐍
	snake.size = 3;
	snake.speed = 10;
	snake.dir = RIGHT;             //初始化定义🐍的方向为RIGHT
	
	for (int i = snake.size - 1; i >= 0; i--)
	{
		snake.coor[i].x = 40 - 10 * i;
		snake.coor[i].y = 10;
		//printf("?%d %d", snake.coor[i].x, snake.coor[i].y);
	}

	//snake.coor[0].x = 40;
	//snake.coor[0].y = 10;
	//snake.coor[1].x = 30;
	//snake.coor[1].y = 10;
	//snake.coor[2].x = 20;
	//snake.coor[2].y = 10;
	
}

void GameDraw()
{
	//双缓冲绘图
	BeginBatchDraw();
	//设置背景颜色
	setbkcolor(RGB(85, 0, 255));
	cleardevice();
	//绘制🐍
	//setfillcolor()
	for (int i = 0; i < snake.size; i++)
	{
		solidcircle(snake.coor[i].x, snake.coor[i].y, 5);
	}
	EndBatchDraw();
}

//移动🐍
void snakeMove()
{
	//移动是坐标发生改变
	//让身体跟着头移动
	for (int i = snake.size - 1; i > 0; i--)
	{
		snake.coor[i] = snake.coor[i - 1];
	}
	switch (snake.dir)
	{
	case UP:
		snake.coor[0].y -= snake.speed;
		if (snake.coor[0].y <= 0)//头跑出了上边界
		{
			snake.coor[0].y = 640;
		}
		break;
	case DOWN:
		snake.coor[0].y += snake.speed;
		break;
	case LEFT:
		snake.coor[0].x -= snake.speed;
		break;
	case RIGHT:
		snake.coor[0].x += snake.speed;
		break;
	}
		
}

//通过按键盘改变🐍的移动方向
void keyControl()
{
	//判断有没有按键盘，如果有按键，就返回真
	if (_kbhit())
	{
		//72   80   75   77    方向键上下左右键值
		switch (_getch())
		{
		case 'w':
		case 'W':
		case 72:
			if (snake.dir != DOWN)
			{
				snake.dir = UP;
			}
			break;
		case 's':
		case 'S':
		case 80:
			if (snake.dir != UP)
			{
				snake.dir = DOWN;
			}
			break;
		case 'a':
		case 'A':
		case 75:
			if (snake.dir != RIGHT)
			{
				snake.dir = LEFT;
			}
			break;
		case 'd':
		case 'D':
		case 77:
			if (snake.dir != LEFT)
			{
				snake.dir = RIGHT;
			}
			break;
		}
	}
	
	
}

int main()
{
	GameInit();
	
	

	while (1)
	{
		GameDraw();
		snakeMove();
		keyControl();
		Sleep(20);
	}

	return 0;
}