#include <stdlib.h>
#include <time.h>
#include <vector>
#include <gl/glut.h>

#define intensivity 1

using namespace std;

GLfloat WinW = 800, WinH = 600;

int gen[] = { -1, 0, 1 };

class SnowFlake {
public:
    GLfloat x;
    GLfloat y;
    GLfloat direction;
    bool fell;
    SnowFlake();
};

SnowFlake::SnowFlake() {
    x = rand() % int(WinW);
    y = WinH;
    direction = gen[rand() % 3];
    fell = false;
}

vector<SnowFlake> SnowFlakes;

void draw() {
    glClear(GL_COLOR_BUFFER_BIT);
    glLoadIdentity();
    glPushMatrix();
    glColor3f(1, 1, 1);
    glBegin(GL_POINTS);
    for (unsigned int i = 0; i < SnowFlakes.size(); i++) {
        glVertex2f(SnowFlakes[i].x, SnowFlakes[i].y);
    }
    glEnd();
    glPopMatrix();
    glutSwapBuffers();
}

void Timer(int value) {
    int n = 0;
    for (unsigned int i = 0; i < SnowFlakes.size(); i++) {
        if (SnowFlakes[i].y > n) {
            SnowFlakes[i].y--;
            SnowFlakes[i].x += SnowFlakes[i].direction;
            SnowFlakes[i].direction = gen[rand() % 3];

        }
        if (SnowFlakes[i].y <= n) {
            SnowFlakes[i].direction = gen[rand() % 3];
            SnowFlakes[i].x += SnowFlakes[i].direction;
            n++;
        }


    }
    for (int i = 0; i < intensivity; i++) SnowFlakes.push_back(SnowFlake());
    glutPostRedisplay();
    glutTimerFunc(3, Timer, 1);
}

void reshape(GLsizei WW, GLsizei WH) {
    glViewport(0, 0, WW, WH);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0, WinW, 0, WinH, 0, 1);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

int main(int argc, char** argv) {
    srand(time(NULL));
    for (int i = 0; i < intensivity; i++) {
        SnowFlakes.push_back(SnowFlake());
    }
    glutInit(&argc, argv);
    glutInitWindowSize(WinW, WinH);
    glutInitWindowPosition(100, 100);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
    glutCreateWindow("RGR 12");
    glutDisplayFunc(draw);
    glutReshapeFunc(reshape);
    glutTimerFunc(1, Timer, 1);
    glutMainLoop();
}