[英]SDL2 C++ Snake Game Self Collision
As a school project, I've made the classic snake game using SDL2 and C++.作为一个学校项目,我使用 SDL2 和 C++ 制作了经典的蛇游戏。 I've already implemented the growing, moving features for the Snake but it was required to make the movement based on a grid, but when I implemented the grid feature, the self-collision was always triggering whenever grow one part, so every time I start the game, and eat the first fruit, the snake dies.我已经为 Snake 实现了增长、移动的功能,但需要基于网格进行移动,但是当我实现网格功能时,每当增长一个部分时总是会触发自碰撞,所以每次我开始游戏,吃第一个水果,蛇就死了。
I've been trying for a while now, from placing a delay to the adding of the tail and delaying the collision check, but to no avail, it's always colliding with itself even though it is not.我已经尝试了一段时间,从放置延迟到添加尾部和延迟碰撞检查,但无济于事,即使不是,它也总是与自身发生碰撞。
I can't see what is wrong with the self collision, I would gladly appreciate it if someone can point out what's wrong.我看不出自我碰撞有什么问题,如果有人能指出什么问题,我将不胜感激。
Snake.h蛇.h
#include "GameObject.h"
#include "common.h"
#include "draw.h"
#include "Food.h"
#include "util.h"
#include <vector>
struct Segment {
int x;
int y;
Segment(int posx, int posy) {
x = posx;
y = posy;
}
};
class Snake :
public GameObject
{
public:
~Snake();
void start();
void update();
void draw();
void outOfBoundsCheck();
void move();
void addSegment(int x, int y);
void selfCollisionCheck(bool hasEaten);
void setHasMoved(bool a);
void setIsAlive(bool a);
int getX();
int getY();
int getWidth();
int getHeight();
bool getIsAlive();
bool getHasMoved();
std::vector<Segment*> const& getV() const;
private:
std::vector<Segment*> body;
SDL_Texture* headTexture;
SDL_Texture* bodyTexture;
int x;
int y;
int width;
int height;
int dx;
int dy;
int tempX;
int tempY;
bool isAlive;
bool hasMoved;
};
Snake.cpp蛇.cpp
Snake::~Snake()
{
}
void Snake::start()
{
// Load Texture
headTexture = loadTexture("gfx/player.png");
bodyTexture = loadTexture("gfx/body.png");
tempX = 0;
tempY = 0;
x = 0;
y = 0;
dx = 0;
dy = 0;
isAlive = true;
hasMoved = false;
width = 0;
height = 0;
SDL_QueryTexture(headTexture, NULL, NULL, &width, &height);
addSegment(x, y);
}
void Snake::update()
{
std::cout << "Head" << body[0]->x << std::endl;
if (body.size() > 1) {
std::cout << "2nd Segment" << body[1]->x << std::endl;
if (body.size() > 2) {
std::cout << "3nd Segment" << body[2]->x << std::endl;
}
}
move();
outOfBoundsCheck();
}
void Snake::draw()
{
if (!isAlive) return; // Cancel the render if player dies
for (int i = 0; i < body.size(); i++) {
blit(headTexture, body[i]->x, body[i]->y);
}
}
void Snake::outOfBoundsCheck()
{
for (int i = 0; i < body.size(); i++) {
if (body[i]->x > SCREEN_WIDTH) {
body[i]->x = 0;
}
if (body[i]->x < 0) {
body[i]->x = SCREEN_WIDTH;
}
if (body[i]->y > SCREEN_HEIGHT) {
body[i]->y = 0;
}
if (body[i]->y < 0) {
body[i]->y = SCREEN_HEIGHT;
}
}
}
void Snake::move()
{
if (app.keyboard[SDL_SCANCODE_W] && dy != 5) {
dx = 0;
dy = -5;
}
if (app.keyboard[SDL_SCANCODE_A] && dx != 5) {
dx = -5;
dy = 0;
}
if (app.keyboard[SDL_SCANCODE_S] && dy != -5) {
dx = 0;
dy = 5;
}
if (app.keyboard[SDL_SCANCODE_D] && dx != -5) {
dx = 5;
dy = 0;
}
Segment* snakeHead = *(body.begin()); //Grid
tempX += dx;
tempY += dy;
if (tempX % 25 == 0) {
snakeHead->x += tempX;
tempX = 0;
}
if (tempY % 25 == 0) {
snakeHead->y += tempY;
tempY = 0;
}
for (int i = body.size() - 1; i > 0; i--) { //For the other parts to follow
body[i]->x = body[i - 1]->x;
body[i]->y = body[i - 1]->y;
}
}
void Snake::addSegment(int x, int y)
{
Segment* seg = new Segment(x, y );
body.push_back(seg);
}
void Snake::selfCollisionCheck(bool hasEaten) // Fail
{
Segment* head = body[0];
if (hasEaten == false) {
for (int i = 1; i < body.size(); i++) {
if (head->x == body[i]->x && head->y == body[i]->y) {
isAlive = false;
break;
}
}
}
else {
return;
}
}
void Snake::setHasMoved(bool a)
{
hasMoved = a;
}
void Snake::setIsAlive(bool a)
{
isAlive = a;
}
int Snake::getX()
{
return x;
}
int Snake::getY()
{
return y;
}
int Snake::getWidth()
{
return width;
}
int Snake::getHeight()
{
return height;
}
bool Snake::getIsAlive()
{
return isAlive;
}
bool Snake::getHasMoved()
{
return hasMoved;
}
std::vector<Segment*> const& Snake::getV() const
{
// TODO: insert return statement here
return body;
}
GameScene.h游戏场景.h
#include "Scene.h"
#include "GameObject.h"
#include "Snake.h"
#include "Food.h"
#include "util.h"
#include "text.h"
#include "SoundManager.h"
class GameScene : public Scene
{
public:
GameScene();
~GameScene();
void start();
void draw();
void update();
void spawnFood();
void collisionLogic();
void selfCollision();
void despawnFood(Food* food);
private:
Snake* snake;
Food* food;
int points;
std::vector<Food*> spawnedFood;
};
GameScene.cpp游戏场景.cpp
#include "GameScene.h"
GameScene::GameScene()
{
// Register and add game objects on constructor
snake = new Snake();
this->addGameObject(snake);
points = 0;
}
GameScene::~GameScene()
{
delete snake;
delete food;
}
void GameScene::start()
{
Scene::start();
// Initialize any scene logic here
initFonts();
spawnFood();
}
void GameScene::draw()
{
Scene::draw();
drawText(110, 20, 255, 255, 255, TEXT_CENTER, "POINTS: %03d", points);
if (snake->getIsAlive() == false) {
drawText(SCREEN_WIDTH / 2, SCREEN_HEIGHT / 2, 255, 255, 255, TEXT_CENTER, "GAME OVER!");
}
}
void GameScene::update()
{
Scene::update();
if (spawnedFood.size() == 0 && spawnedFood.size() != 1) {
spawnFood();
}
collisionLogic();
selfCollision();
}
void GameScene::spawnFood()
{
int random = rand() % 720;
if (random % 25 != 0) {
random = rand() % 720;
}
else {
Food* food = new Food();
this->addGameObject(food);
food->setPosition(rand() % SCREEN_WIDTH, rand() % SCREEN_HEIGHT);
spawnedFood.push_back(food);
}
}
void GameScene::collisionLogic()
{
Segment* head = snake->getV()[0];
std::vector<Segment*> snakeBody = snake->getV();
for (int i = 0; i < objects.size(); i++) {
Food* food = dynamic_cast<Food*>(objects[i]);
if (food != NULL) {
int collision = checkCollision(
head->x, head->y, snake->getWidth(), snake->getHeight(),
food->getX(), food->getY(), food->getWidth(), food->getHeight()
);
if (collision == 1) {
despawnFood(food);
snake->addSegment(snakeBody[snakeBody.size() - 1]->x, snakeBody[snakeBody.size() - 1]->y); //Adds a part to the snake
points++;
break;
}
}
}
}
void GameScene::selfCollision()
{
std::vector<Segment*> body = snake->getV();
Segment* head = snake->getV()[0];
for (int i = 1; i < snake->getV().size(); i++) {
if (head->x == body[i]->x && head->y == body[i]->y) {
snake->setIsAlive(false);
break;
}
}
}
void GameScene::despawnFood(Food* food)
{
int index = -1;
for (int i = 0; i < spawnedFood.size(); i++) {
if (food == spawnedFood[i]) {
index = i;
break;
}
}
if (index != -1) {
spawnedFood.erase(spawnedFood.begin() + index);
delete food;
}
}
似乎在网格运动方面我有一些逻辑错误,因为当我重新编码所有内容并将网格运动更改为基于单元格而不是通过将屏幕宽度和高度除以我的蛇的像素大小而使用模条件时使用它作为我运动的坐标,一切都恢复正常,碰撞错误消失了。
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