如何让蛇咬人
How to make the snake bite?
我正试图用SFML在C++中制作一个蛇游戏。下面是我的代码。问题是，我不知道我怎么可能让蛇咬自己：每个蛇块都占据最后一个的位置，从而形成一条完全笔直的蛇。所以这更像是一个算法问题。感谢您的建议：）BTW没有放入hashtages和<在include中，因为编辑器将其删除：/BTW2：寻找类似的回答，但没有一个是用我的方法或另一种语言。给你：
#include <SFML/Window.hpp>
#include <SFML/Graphics.hpp>
#include <SFML/System.hpp>
#include <SFML/Audio.hpp>
#include <deque>
void selfIncrement();
sf::Event event;
sf::Clock clockSnake;
sf::Time elapse;
enum Direction { Up, Down, Left, Right};
int dir = Up;
int n = 1;
class SnakeBlock
{
public:
SnakeBlock * next;
sf::Texture texture;
sf::Sprite snakeblock;
int lastX, lastY;
};
std::deque<SnakeBlock> Snake;
int main()
{
elapse = clockSnake.getElapsedTime();
sf::Music epicMusic;
epicMusic.openFromFile("epicmusic.wav");
epicMusic.play();
SnakeBlock snakeHead;
snakeHead.texture.loadFromFile("spritesheetsnake.png", sf::IntRect(0,0,20,22));
snakeHead.snakeblock.setTexture(snakeHead.texture);
SnakeBlock snakeBody1;
snakeBody1.snakeblock.setTexture(*(snakeHead.snakeblock.getTexture()));
SnakeBlock snakeBody2;
snakeBody2.snakeblock.setTexture(*(snakeHead.snakeblock.getTexture()));
Snake.push_front(snakeHead);
Snake.push_front(snakeBody1);
Snake.push_front(snakeBody2);
Snake[2].snakeblock.setPosition(500,350);
Snake[1].snakeblock.setPosition(475, 338);
Snake[0].snakeblock.setPosition(450, 316);
sf::RenderWindow window(sf::VideoMode(1028,768), "SFML Snake");
window.setFramerateLimit(60);
while(window.isOpen())
{
while(window.pollEvent(event))
{
switch(event.type)
{
case sf::Event::Closed:
epicMusic.stop();
window.close();
break;
default:
break;
}
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Left))
{
dir = Left;
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Right))
{
dir = Right;
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Down))
{
dir = Down;
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Up))
{
dir = Up;
}
if(dir == Up)
{
Snake[0].snakeblock.move(0,-2);
Snake[n].snakeblock.setPosition(Snake[n-1].snakeblock.getPosition().x, Snake[n-1].snakeblock.getPosition().y+20);
}
if(dir == Down)
{
Snake[0].snakeblock.move(0,2);
Snake[n].snakeblock.setPosition(Snake[n-1].snakeblock.getPosition().x, Snake[n-1].snakeblock.getPosition().y-20);
}
if(dir == Left)
{
Snake[0].snakeblock.move(-2,0);
Snake[n].snakeblock.setPosition(Snake[n-1].snakeblock.getPosition().x+20, Snake[n-1].snakeblock.getPosition().y);
}
if(dir == Right)
{
Snake[0].snakeblock.move(2,0);
Snake[n].snakeblock.setPosition(Snake[n-1].snakeblock.getPosition().x-20, Snake[n-1].snakeblock.getPosition().y);
}
window.clear(sf::Color::Red);
n++;
if( n > 2)
{
n = 1;
}
//selfIncrement();
for(unsigned int m = 0; m < Snake.size(); m++)
{
window.draw(Snake[m].snakeblock);
}
window.display();
}
return 0;
}
/*void selfIncrement()
{
elapse = clockSnake.getElapsedTime();
if(elapse.asSeconds() > 0.10)
{
n++;
clockSnake.restart();
}
if(n > Snake.size())
{
n = 1;
}
}
*/
使用新原理的新代码：：
#include <SFML/Window.hpp>
#include <SFML/Graphics.hpp>
#include <SFML/System.hpp>
#include <SFML/Audio.hpp>
#include <deque>
void advanceStep();
sf::Event event;
sf::Clock clockSnake;
sf::Time elapse;
enum Direction { Up, Down, Left, Right};
sf::Vector2i direction;
int dir = Up;
int n = 1;
class SnakeBlock
{
public:
sf::Texture texture;
sf::Sprite snakeblock;
int dir = 0;
int lastX, lastY;
};
SnakeBlock element;
std::deque<SnakeBlock> Snake;
int main()
{
elapse = clockSnake.getElapsedTime();
sf::Music epicMusic;
epicMusic.openFromFile("epicmusic.wav");
epicMusic.play();
SnakeBlock snakeHead;
snakeHead.texture.loadFromFile("spritesheetsnake.png", sf::IntRect(0,0,20,22));
snakeHead.snakeblock.setTexture(snakeHead.texture);
SnakeBlock snakeBody1;
snakeBody1.snakeblock.setTexture(*(snakeHead.snakeblock.getTexture()));
SnakeBlock snakeBody2;
snakeBody2.snakeblock.setTexture(*(snakeHead.snakeblock.getTexture()));
Snake.push_front(snakeHead);
Snake.push_front(snakeBody1);
Snake.push_front(snakeBody2);
Snake[2].snakeblock.setPosition(500,350);
Snake[1].snakeblock.setPosition(475, 338);
Snake[0].snakeblock.setPosition(450, 316);
sf::RenderWindow window(sf::VideoMode(1028,768), "SFML Snake");
window.setFramerateLimit(10);
while(window.isOpen())
{
while(window.pollEvent(event))
{
switch(event.type)
{
case sf::Event::Closed:
epicMusic.stop();
window.close();
break;
default:
break;
}
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Left))
{
dir = Left;
direction.x = -1;
direction.y = 0;
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Right))
{
dir = Right;
direction.x = 1;
direction.y = 0;
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Down))
{
dir = Down;
direction.x = 0;
direction.y = -1;
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Up))
{
dir = Up;
direction.x = 0;
direction.y = 1;
}
if(dir == Up)
{
Snake[0].snakeblock.move(0,-2);
Snake[1].snakeblock.setPosition(Snake[0].snakeblock.getPosition().x, Snake[0].snakeblock.getPosition().y+20);
Snake[2].snakeblock.setPosition(Snake[1].snakeblock.getPosition().x, Snake[1].snakeblock.getPosition().y+20);
}
if(dir == Down)
{
Snake[0].snakeblock.move(0,2);
Snake[1].snakeblock.setPosition(Snake[0].snakeblock.getPosition().x, Snake[0].snakeblock.getPosition().y-20);
Snake[2].snakeblock.setPosition(Snake[1].snakeblock.getPosition().x, Snake[1].snakeblock.getPosition().y-20);
}
if(dir == Left)
{
Snake[0].snakeblock.move(-2,0);
Snake[1].snakeblock.setPosition(Snake[0].snakeblock.getPosition().x+20, Snake[0].snakeblock.getPosition().y);
Snake[2].snakeblock.setPosition(Snake[1].snakeblock.getPosition().x+20, Snake[1].snakeblock.getPosition().y);
}
if(dir == Right)
{
Snake[0].snakeblock.move(2,0);
Snake[1].snakeblock.setPosition(Snake[0].snakeblock.getPosition().x-20, Snake[0].snakeblock.getPosition().y);
Snake[2].snakeblock.setPosition(Snake[1].snakeblock.getPosition().x-20, Snake[1].snakeblock.getPosition().y);
}
window.clear(sf::Color::Red);
advanceStep();
for(unsigned int m = 0; m < Snake.size(); m++)
{
window.draw(Snake[m].snakeblock);
}
window.display();
}
return 0;
}
void advanceStep()
{
sf::Vector2f headpos(Snake[0].snakeblock.getPosition());
headpos.x += 22 * direction.x;
headpos.y += 22 * direction.y;
Snake[0].snakeblock.setPosition(headpos);
Snake.pop_back();
Snake.push_front(Snake[0]);
}
新的代码考虑到了你们所有人所说的一切，但现在蛇消失了，可能是因为pop_back。。
#include <SFML/Window.hpp>
#include <SFML/Graphics.hpp>
#include <SFML/System.hpp>
#include <SFML/Audio.hpp>
#include <deque>
void advanceStep();
sf::Event event;
sf::Clock clockSnake;
sf::Time elapse;
enum Direction { Up, Down, Left, Right};
sf::Vector2i direction(0, 0);
int dir = Up;
class SnakeBlock
{
public:
sf::Texture texture;
sf::Sprite snakeblock;
int dir;
};
std::deque<SnakeBlock> Snake;
int main()
{
elapse = clockSnake.getElapsedTime();
sf::Music epicMusic;
epicMusic.openFromFile("epicmusic.wav");
epicMusic.play();
SnakeBlock snakeHead;
snakeHead.texture.loadFromFile("spritesheetsnake.png", sf::IntRect(0,0,20,22));
snakeHead.snakeblock.setTexture(snakeHead.texture);
SnakeBlock snakeBody1;
snakeBody1.snakeblock.setTexture(*(snakeHead.snakeblock.getTexture()));
SnakeBlock snakeBody2;
snakeBody2.snakeblock.setTexture(*(snakeHead.snakeblock.getTexture()));
Snake.push_back(snakeHead);
Snake.push_back(snakeBody1);
Snake.push_back(snakeBody2);
Snake[2].snakeblock.setPosition(500,350);
Snake[1].snakeblock.setPosition(475, 338);
Snake[0].snakeblock.setPosition(450, 316);
sf::RenderWindow window(sf::VideoMode(1028,768), "SFML Snake");
window.setFramerateLimit(1);
while(window.isOpen())
{
while(window.pollEvent(event))
{
switch(event.type)
{
case sf::Event::Closed:
epicMusic.stop();
window.close();
break;
default:
break;
}
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Left))
{
direction.x = -1;
for(int i = 1; i < Snake.size(); i++)
{
Snake[i].snakeblock.setPosition(Snake[i+1].snakeblock.getPosition().x-20, Snake[i+1].snakeblock.getPosition().y);
}
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Right))
{
direction.x = 1;
for(int j = 1; j < Snake.size(); j++)
{
Snake[j].snakeblock.setPosition(Snake[j+1].snakeblock.getPosition().x+20, Snake[j+1].snakeblock.getPosition().y);
}
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Down))
{
direction.y = -1;
for(int l = 1; l < Snake.size(); l++)
{
Snake[l].snakeblock.setPosition(Snake[l+1].snakeblock.getPosition().x, Snake[l+1].snakeblock.getPosition().y-22);
}
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Up))
{
direction.y = 1;
for(int o = 1; o < Snake.size(); o++)
{
Snake[o].snakeblock.setPosition(Snake[o+1].snakeblock.getPosition().x, Snake[o+1].snakeblock.getPosition().y+22);
}
}
window.clear(sf::Color::Red);
advanceStep();
for(unsigned int m = 1; m < Snake.size(); m++)
{
window.draw(Snake[m].snakeblock);
}
window.display();
}
return 0;
}
void advanceStep()
{
sf::Vector2f headpos;
headpos.x = Snake[0].snakeblock.getPosition().x;
headpos.y = Snake[0].snakeblock.getPosition().y;
headpos.x += 22 * direction.x;
headpos.y += 22 * direction.y;
SnakeBlock element;
element.snakeblock.setPosition(headpos);
Snake.pop_back();
Snake.push_front(element);
}
您的实现有很多问题。与其指出每一个问题，不如简单介绍一下。假设你的蛇是一个分段列表，具有最大长度：
- 在每个更新步骤中：
- 下一个位置=头部位置+当前方向
- 在下一个位置的队列头添加段
- 当队列长度大于最大长度时，请删除队列尾部的一段
- 在键盘输入时，只需更改当前方向
- 如果您需要更改蛇的长度，只需更改最大长度即可——更新步骤将调整蛇的长度
从语义上讲，碰撞是指蛇的头部撞到身体的任何其他部位。
要检测冲突，请在每个更新步骤中实现此功能。检查头部与身体其余部分的接触情况。如果有一个十字路口，就会发生碰撞。
顺便说一句，如果你想在最大蛇形长度减少时获得更平滑的"收缩"效果，你可以例如每次更新最多删除两个段（当队列长度>最大长度，而删除的段<收缩率）。
编辑：处理您在下面的评论，想知道如何根据整数（或枚举，我看到您现在使用的是相同的概念）改变方向；这里还有一些伪代码：
Vec2 direction(0, 0);
if (currentDirection == Up)
direction.y = -1;
else if (currentDirection == Down)
direction.y = 1;
else if (currentDirection == Left)
direction.x = -1;
else if (currentDirection == Right)
direction.x = 1;
// direction is now a vector containing an x and y offset, which you can
// apply to the current position of the snake head to find the next
// position.
基本原理是，你需要检测头部是否到达了自己的任何一块——如果是，它就"自己被咬了"。
因此，当你刚刚移动蛇（包括"生长"它，如果适用）时，检查头部是否与构成蛇的任何其他"块"的位置匹配。
编辑：要让蛇"摆动"，你需要使用一个"记住"头部移动的方向，每次移动都应该将该块的方向"洗牌"到它后面的块。
换句话说，将dir条目添加到SnakeBlock，并使用该条目来移动每个块。
这就是过度复杂化的结果。
因为您使用std::deque，所以不需要"下一个"字段。或"移动"方法。块也不需要单独的纹理（这意味着所有纹理都是唯一的，这是不正确的）。
完整游戏的大致轮廓（省略构造函数）：
struct Vector2{
int x, y;
};
typedef std::deque<Vector2> Vec2Deque;
struct Snake{
Vec2 direction; //(+-1, +-1)
int blockSize;
Vec2Deque blocks;//for blocks you only need their coordinates.
void render(){
for(size_T i = 0; i < blocks.size(); i++)
renderSpriteAt(blocks[i]);
}
void advanceStep(){
Vector2 headPos = blocks[0];//take current head pos
headPos.x += blockSize * direction.x; //calculate next position based on direction
headPos.y += blockSize * direction.y; //and block size. Direction is 2component vector.
blocks.pop_back();//remove last element
blocks.push_front(headPos);//insert new element with new position as a head.
//That'll automatically create illusion of movement.
}
};
这将模拟经典的基于网格的蛇。
如果你想要更好的蛇（它移动平稳，可以以小角度（比如向左1度）转弯），事情会变得更复杂。
简单思考。另请参见KISS原则。
新的代码考虑到了你们所有人所说的一切，但现在蛇消失了，可能是因为pop_back
替换此：
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Left))
{
direction.x = -1;
for(int i = 1; i < Snake.size(); i++)
{
Snake[i].snakeblock.setPosition(Snake[i+1].snakeblock.getPosition().x-20, Snake[i+1].snakeblock.getPosition().y);
}
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Right))
{
direction.x = 1;
for(int j = 1; j < Snake.size(); j++)
{
Snake[j].snakeblock.setPosition(Snake[j+1].snakeblock.getPosition().x+20, Snake[j+1].snakeblock.getPosition().y);
}
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Down))
{
direction.y = -1;
for(int l = 1; l < Snake.size(); l++)
{
Snake[l].snakeblock.setPosition(Snake[l+1].snakeblock.getPosition().x, Snake[l+1].snakeblock.getPosition().y-22);
}
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Up))
{
direction.y = 1;
for(int o = 1; o < Snake.size(); o++)
{
Snake[o].snakeblock.setPosition(Snake[o+1].snakeblock.getPosition().x, Snake[o+1].snakeblock.getPosition().y+22);
}
}
这个：
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Left))
{
direction.x = -1;
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Right))
{
direction.x = 1;
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Down))
{
direction.y = -1;
for(int l = 1; l < Snake.size(); l++)
}
if(sf::Keyboard::isKeyPressed(sf::Keyboard::Up))
{
direction.y = 1;
}
你不应该在advanceStep之外的任何地方更新snake。您应该使用push/pop或那个移动元素的循环，而不是两者都使用。你不知道，你可以在所有的循环中使用"i"，并且不需要每次都选择不同的变量名，对吧？
如果你仍然对蛇有问题，试着写一个卷轴射击游戏。例如：
- 偏执狂
- 滚动射击
除非你想把粒子系统添加到这些游戏中，否则它们应该比蛇更容易，因为在这些游戏中一个对象只有一个精灵。
据我所知，目前你的蛇仍然是一条直线，你希望它能像其他游戏中一样转动。
我在游戏中所做的，我有两个数据结构，一个用于蛇的部分（位置和方向），另一个用于转弯（方向和位置）。
在游戏循环中，蛇形部分沿其方向移动，但如果其位置与转弯方向匹配，则蛇形部分会将其方向更改为转弯方向，并相应地更新其位置。
当你把它应用到蛇的尾巴部分时，转弯就被去除了。并添加了当你检测到按键按下时，捕捉到它的方向和位置就是蛇头的位置。
我的实现就在这里，你可以看看我在说什么。
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