OpenGL - Coloring

#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>


void init(){
    glClearColor(1.0, 1.0, 1.0, 1.0);
    gluOrtho2D(-1.0,10.0,-1.0,10.0);
}

void display(){
    glClear(GL_COLOR_BUFFER_BIT);

    glBegin(GL_POLYGON);
        glColor3f(1.0, 0.0, 0.0);
        glVertex2f(1.0,1.0);

        glColor3f(1.0,1.0,0.0);
        glVertex2f(4.0,8.0);

        glColor3f(1.0,0.0,1.0);
        glVertex2f(8.0,1.0);

    glEnd();

    glFlush();
}


int main(int argc, char *argv[]){
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(400, 300);
    glutInitWindowPosition(200, 100);
    glutCreateWindow("OpenGL Program");

    glutDisplayFunc(display);
    init();

    glutMainLoop();

    return 0;
}

OpenGL - Coloring