Hoeses

#include <stdlib.h>
#include <time.h>
#include <stdbool.h>
#include <SDL.h>
#include <SDL2_gfxPrimitives.h>
#define WINDOW_WIDTH 1200
#define WINDOW_HEIGHT 900

typedef struct Vector2{
    double x, y;
}Vector2;

typedef struct Snow{
    Vector2 pos;
    double vx;
    int r;
    bool dir;
    struct Snow *next;
}Snow;

Snow *append (Snow *head, Vector2 pos, int r, double vx) {
    Snow *new;
    new = (Snow*) malloc(sizeof(Snow));
    new->pos.x = pos.x;
    new->pos.y = pos.y;
    new->r = r;
    new->dir = rand()&1;
    if (new->dir == 1) new->vx = vx;
    else new->vx = -vx;
    new->next = NULL;

    if(head == NULL) {
        return new;
    }

    Snow *current = head;
    while (current->next != NULL) {
        // iterates to the end of the list
        current = current->next;
    }
    current->next = new;
    return head;
}

Snow *freeSnow_outside (Snow *head) {
    while (head != NULL) {
        if (head->pos.y > head->r + WINDOW_HEIGHT) {
            Snow* tmp = head;
            head = head->next;
            free(tmp);
        } else {
            break;
        }
    }
    return head;
}

void freeSnow (Snow *snow) {
    Snow *tmp;
    while (snow != NULL) {
        tmp = snow;
        snow = snow->next;
        free(tmp);
    }
}

Snow *generateSnow (Snow *head) {
    // random sugár
    int r = rand() % 5 + 2;
    // random x pozíció az ablakon belül 10px margóval
    Vector2 pos = {(rand() % (WINDOW_WIDTH-10) - 10) + 10, pos.x};
    pos.y = 2*r;
    double vx = (double)r/5;

    head = append(head, pos, r, vx);
    return head;
}

Snow *snowFall (Snow *head){
    Snow *current = head;
    while (current != NULL) {
        // iterates to the end of the list

        if (current->dir) // jobbra kezdi
            current->pos.x += cos(current->vx / 20) / 2;
        else // balra kezdi
            current->pos.x -= cos(current->vx / 20) / 2;

        int speed = 6;
        current->pos.y += fabs(sin(current->vx)*speed);
        current->vx ++;
        if (current->vx >= 360)
            current->vx = 0;

        current = current->next;
    }
    return current;
}

void drawSnow (SDL_Renderer *renderer, Snow *head, SDL_Color color) {
    Snow *current = head;
    while (current != NULL) {
        // iterates to the end of the list
        filledCircleRGBA(renderer, current->pos.x, current->pos.y, current->r, color.r, color.g, color.b, color.a);
        current = current->next;
    }
}

Uint32 timer(Uint32 ms, void *param) {
    SDL_Event event;
    event.type = SDL_USEREVENT;
    SDL_PushEvent(&event);
    return ms;
}

int main(int argc, char *argv[]) {
    SDL_Window *window;
    SDL_Event event;
    SDL_Renderer *renderer;

    SDL_Color foreground = {255, 255, 255, 150};
    SDL_Color background = {23, 82, 145, 255};

    SDL_Init(SDL_INIT_EVERYTHING);
    SDL_CreateWindowAndRenderer(WINDOW_WIDTH, WINDOW_HEIGHT, 0, &window, &renderer);
    SDL_SetRenderDrawColor(renderer, background.r, background.g, background.b, background.a);
    SDL_RenderClear(renderer);
    SDL_TimerID id = SDL_AddTimer(20, timer, NULL);

    srand(time(NULL));
    Snow *snow = NULL;

    while (SDL_WaitEvent(&event) && event.type != SDL_QUIT) {
        snow = generateSnow(snow);
        drawSnow(renderer, snow, background);
        snowFall(snow);
        drawSnow(renderer, snow, foreground);
        snow = freeSnow_outside(snow);
        SDL_RenderPresent(renderer);
        SDL_Delay(5);
    }
    freeSnow(snow);
    SDL_RemoveTimer(id);
    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();
    return EXIT_SUCCESS;
}