opengl c++ easy colision with struct

//to be continued...
//key rebulid
//win.h
#ifdef __APPLE__
#include<GLUT/glut.h>
#include<openGL/openGL.h>

#else
#include<GL/glut.h>
#endif
#include <stdlib.h>
GLfloat d = 0.1;

GLfloat y2=-0.7f;
int refreshMillis = 30;


struct kulka
{ 
                  
GLfloat x;
GLfloat y ;

} kulka , wall= {1.0 , 1.0} , speed= {0.04, 0.07};
    
struct player
{

GLfloat x;
GLfloat y;

};


                 

struct point
{
GLfloat x;
GLfloat y;
};



void initRendering()
{
    glEnable(GL_DEPTH_TEST);   
}

void reshape(int w,int h)
{
    glViewport(0,0,w,h);

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();
}                                                                      //p.


void drawBall1()
{

    glColor3f(0.0,1.0,.0);

    glPushMatrix();

    glTranslatef(kulka.x,kulka.y,0.0);

    glutSolidSphere(d,20,20);

    glPopMatrix();
}

void drawBall2(GLfloat * x2)
{

    glColor3f(1.0,0.0,.0);

    glPushMatrix();

    glTranslatef(* x2,-0.7,0.0);

    glutSolidSphere(d,20,20);

    glPopMatrix();

}

void drawballs()
{

point  point1, point2, point3, point4, point5, point6;
point1.x=0.5;
point1.y=0.7;
point2.x=-0.5;
point2.y=0.7;
point3.x=0.0;
point3.y=0.7;


   glColor3f(1.0,1.0,.0);

 

 glPushMatrix();
    glTranslatef(point1.x,point1.y,0.0);
 glutSolidSphere(d,20,20);
glPopMatrix();
glPushMatrix();
  glTranslatef(point2.x,point2.y,0.0);
 glutSolidSphere(d,20,20);

glPopMatrix();
glPushMatrix();
  glTranslatef(point3.x,point3.y,0.0);
 glutSolidSphere(d,20,20);

glPopMatrix();

}

void update()
{
kulka.x+=speed.x;
kulka.y+=speed.y;
if (kulka.x>wall.x)
{
speed.x=-speed.x;
}
if ( kulka.y>wall.y)
{
speed.y=-speed.y;
}
  if(kulka.x<-wall.x)
 {
speed.x=-speed.x;
}
if  ( kulka.y<-wall.y)
{
speed.y=-speed.y;
}
}
void keyboard (unsigned char key, int x, int y )   //core dumpted p.
{

GLfloat *x2;

switch (key) {
case 'd':
*x2= *x2+0.1f;
glutPostRedisplay();
break;
case 'a':
*x2= *x2-0.1f;
glutPostRedisplay();
break;
}
}



void display()
{
    glClear(GL_COLOR_BUFFER_BIT);

    glMatrixMode(GL_MODELVIEW);

    glLoadIdentity();

    glShadeModel(GL_SMOOTH);
GLfloat * x2;
 update();
 drawballs();
    drawBall1();                      //zielona
    drawBall2(x2);                                        

                                                  //czerwona

 






    glutSwapBuffers();
}




void Timer(int value)          //kopjuj wklej p.
 {
   glutPostRedisplay();    // Post a paint request to activate display()
   glutTimerFunc(refreshMillis, Timer, 0); // subsequent timer call at milliseconds
}


int main(int argc,char **argv)                   //kopjuj wklej p.
{
    glutInit(&argc,argv);

    glutInitDisplayMode(GLUT_DOUBLE);

    glutInitWindowSize(400,400);

    glutCreateWindow("gra Q");

 

    glutDisplayFunc(display);

  

    glutReshapeFunc(reshape);

  glutKeyboardFunc(keyboard);

glutTimerFunc(0, Timer, 0);
 initRendering();
    glutMainLoop();

    return 0;
}