Expected constructor, destructor, or type conversion before '.' token

struct Gf3 {
    GLfloat x;
    GLfloat y;
    GLfloat z;
} p1,p2,p3,t;
 
t.x = 0.0; t.y = 0.0; t.z = 1.0;
p1.x = 0.0; p1.y = 0.942809; p1.z = -0.333333;
p2.x = -0.816497; p2.y = -0.471405; p2.z = -0.333333;
p3.x = 0.816497; p3.y = -0.471405; p3.z = -0.333333;

#include <windows.h>
#include <GL/glut.h>
 
#include <stdlib.h>
#include <iostream>
using namespace std;
 
struct Gf3 {
    GLfloat x;
    GLfloat y;
    GLfloat z;
} p1,p2,p3,t;
 
t.x = 0.0; t.y = 0.0; t.z = 1.0;
p1.x = 0.0; p1.y = 0.942809; p1.z = -0.333333;
p2.x = -0.816497; p2.y = -0.471405; p2.z = -0.333333;
p3.x = 0.816497; p3.y = -0.471405; p3.z = -0.333333;
 
void myInit(void);
void display(void);
void reshape(int,int);
 
int main(int argc, char *argv[])
{
    glutInit(&argc, argv);
    glutInitDisplayMode( GLUT_DOUBLE | GLUT_DEPTH );
    glutInitWindowSize(640, 640);
    glutInitWindowPosition(300, 0);
    glutCreateWindow("Aproximization sphere");
 
    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
 
    myInit();
    glutMainLoop();
 
    return EXIT_SUCCESS;
}
 
void myInit(void) {
    glOrtho(-2.0, 2.0, -2.0, 2.0, -10.0, 10.0);
    glDepthFunc(GL_LESS);
}
 
void display(void) {
    glClear(GL_COLOR_BUFFER_BIT);
    glClear(GL_DEPTH_BUFFER_BIT);
 
    glutSwapBuffers();
}
 
void reshape(int width, int height){
    glViewport(0,0,width,height);
    glutPostRedisplay();
}

int main(){
    int a = 5;
    cout << a;
    return 0;
}

void f(void){
    int a = 5;
    cout << a;
}
 
int main(){
    f();
    return 0;
}