Bangun Dasar Grafika SegiTiga

#include <GL/glut.h>           
#include <windows.h>   
#include <GL/gl.h>
void init (void) {   
glClearColor (1.0, 1.0, 1.0, 0.0);   
glLineWidth (1.0);   
glColor3f (1.0, 0.0, 0.0);           
glOrtho (-6,6, -6,6, -6,6);   
}               
void Display (void) {       
glClear (GL_COLOR_BUFFER_BIT);   
glBegin (GL_LINES);   
glVertex2f (-5.5, 0.0);       
glColor3f (1.0, 0.0, 0.0);
glVertex2f (5.5, 0.0);       
glEnd ();       
glBegin (GL_LINES);       
glVertex2f (0.0, -5.5);   
glColor3f (1.0, 0.0, 0.0);   
glVertex2f (0.0, 5.5);       
glEnd ();               
glBegin (GL_TRIANGLES);           
glColor3f (1.0, 0.0, 0.0);       
glVertex2f (1.0, 1.0);       
glColor3f (0.0, 0.0, 1.0);       
glVertex2f (3.0, 1.0);
glColor3f (0.0, 1.0, 0.0);
glVertex2f (2.0, 4.0);
glEnd ();
glBegin (GL_TRIANGLES);           
glColor3f (0.0, 1.0, 0.0);       
glVertex2f (-2.0, -1.0);       
glColor3f (1.0, 0.0, 0.0);       
glVertex2f (-3.0, -4.0);
glColor3f (0.0, 0.0, 1.0);
glVertex2f (-1.0, -4.0); 
glEnd ();
glBegin (GL_TRIANGLES);           
glColor3f (1.0, 1.0, 0.0);       
glVertex2f (1.0, -1.0);       
glColor3f (0.0, 1.0, 1.0);       
glVertex2f (2.0, -4.0);
glColor3f (1.0, 0.43, 0.78);
glVertex2f (3.0, -1.0);
glEnd ();
glBegin (GL_TRIANGLES);           
glColor3f (1.0, 0.43, 0.78);       
glVertex2f (-1.0, 4.0);
glColor3f (1.0, 1.0, 0.0);       
glVertex2f (-3.0, 4.0);       
glColor3f (0.0, 1.0, 1.0);       
glVertex2f (-2.0, 1.0);
glEnd ();
glutSwapBuffers ();
}
int main (int argc, char** argv) {   
glutInit (&argc, argv);   
glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);   
glutInitWindowPosition (0, 0);
glutInitWindowSize (1500, 1500);
glutCreateWindow ("bangun dasar grafik");   
init ();
glutDisplayFunc (Display);
glutMainLoop ();
return 0;
}