Contoh Program Membuat Hujan.C++

#include <GL/glut.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>

typedef struct {//MEMBUAT VARIABEL
        float e[];
        float mY[4][4];
}
        VEKTOR,MATRIK;
      
typedef struct{
        double x;
        double y;
}TITIK;

typedef struct{
        double red,green,blue;
}WARNA;

void setColor(WARNA col){
     glColor3f(col.red,col.green,col.blue);//metode pewarnaan
}

VEKTOR operator * (MATRIK a, VEKTOR b)
{
       VEKTOR c;
       int i,j;
       for (i=0;1<3;i++){
           c.e[i]=0;
           for (j=0;j<3;j++)
           c.e[i]+=a.mY[i][j]*b.e[j];
           }
           return c;
}
VEKTOR titikV(TITIK pnt,TITIK transPoint)
{
       VEKTOR vec;
       vec.e[0]=pnt.x - transPoint.x;
       vec.e[1]=pnt.y - transPoint.y;
       vec.e[2]=1.;
       return vec;
}

TITIK vector2point(VEKTOR vec,TITIK transPoint)
{
      TITIK pnt;
      pnt.x=vec.e[0] + transPoint.x;
      pnt.y=vec.e[1] + transPoint.y;
      return pnt;
}
    
void transform2D(TITIK p[], MATRIK mat, int n,float xCentre, float yCentre){
     VEKTOR vec;
     TITIK transPoint;
     transPoint.x= xCentre;
     transPoint.y= yCentre;
     for (int i=0; i<n; i++){
         vec=titikV (p[i],transPoint);
         vec=mat*vec;
         p[i]=vector2point (vec,transPoint);
      } 
}
void Line(double x1, double y1, double x2, double y2){
     glBegin(GL_LINES);
     glVertex2d(x1,y1);
     glVertex2d(x2,y2);
     glEnd();
}
void hujan(){
     static TITIK hjn[295];
     static int bunyi=0;
     int i;
   
     if(bunyi==0){
                  for (i=0;i<295;i++){
                      hjn[i].x=rand()%10000;
                      hjn[i].y=rand()%10000;
                      }
                      }
                      for (i=0;i<295;i++){
                          hjn[i].x-=1;
                          hjn[i].y-=1;
                          if (hjn[i].x<0||hjn[i].y<0){
                          hjn[i].x=rand()%800;
                          hjn[i].y=rand()%600;
                      }
                  }
                  glColor3f(1,1,1);
                  for (i=0;i<200;i++){
                      Line(hjn[i].x, hjn[i].y, hjn[i].x-4, hjn[i].y-2);
                      }
                      bunyi++;
}

void display (void){
     glClear (GL_COLOR_BUFFER_BIT);
     hujan();
     glutSwapBuffers();
}

int main(int argc,char **argv){
  
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB);
    glutInitWindowPosition(100,100);
    glutInitWindowSize(800,600);
    glutCreateWindow("Leni");
    glClearColor(0.0, 0.0, 0.0, 0);
    gluOrtho2D(0.,800.,0.,600.);
    glutIdleFunc(display);
    glutDisplayFunc(display);
    glutMainLoop();
}
  
 Outputnya :