#include "stdlib.h"
#include "gl/glut.h"

int x=1;
int a=4;

void Triangles(){
 glBegin(GL_TRIANGLES);
  glColor3f(0.5,0.5,0.5);
  glVertex2f (0.,0.);
  glVertex2f(10.,30.);
  glVertex2f(-10.,30.);
  glColor3f(0,0,0);
  glVertex2f (0.,0.);
  glVertex2f(-10.,-30.);
  glVertex2f(10.,-30.);
 glEnd();
}

void renderScene(void){

 glClear(GL_COLOR_BUFFER_BIT);
 glClearColor(1,1,1,1);
 glRotatef(a,0,0,1);//sudut
  Triangles();
 glFlush();
}

void myKeyboard(unsigned char key,int x1,int y){
 if(key == 'k'){
  x=1;
  glRotatef(-4,0,0,1);
 }
else if(key =='l')
{
 x=2;
 glRotatef(4,0,0,1);
 }
}

void timer(int value){
 if (x==1)
{
 a=4;
 
}
else if(x==2)
{
 
 a=-4;
}


 glutPostRedisplay();
 glutTimerFunc(50,timer,0);
}


void main(int argc,char **argv){
 glutInit(&argc,argv);
 glutInitWindowPosition(100,100);
 glutInitWindowSize(400,400);
 glutCreateWindow("Baling-baling");
 gluOrtho2D(-50.,50.,-50.,50.);
 glutDisplayFunc(renderScene);
 glutTimerFunc(1,timer,0);
 glutKeyboardFunc(myKeyboard);
 glutMainLoop();
}