/* stairs2.c by G.S.Adhar */



#include <stdlib.h>
#include <GL/glut.h>
#include <math.h>

float corners[6][3] = {{5,0,0}, {5,2,0}, {-5,2,0}, {-5,0,0}, {-5,2,-2}, {5,2,-2}};

void OneStep()
{
	  glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);
	  glColor3f(0.0,0.0,0.0);
       glBegin(GL_POLYGON);
	        glVertex3fv(corners[0]);
			glVertex3fv(corners[1]);
			glVertex3fv(corners[2]);
			glVertex3fv(corners[3]);
	   glEnd();
   
	   glBegin(GL_QUADS);
	      glVertex3fv(corners[1]);
	      glVertex3fv(corners[2]);
	      glVertex3fv(corners[4]);
	      glVertex3fv(corners[5]);
	    glEnd();

		glBegin(GL_TRIANGLES);
	        glVertex3fv(corners[0]);
			glVertex3fv(corners[1]);
			glVertex3fv(corners[5]);
		glEnd();

		glBegin(GL_TRIANGLES);
	        glVertex3fv(corners[3]);
			glVertex3fv(corners[2]);
			glVertex3fv(corners[4]);
		glEnd();
		glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);
		glColor3f(1.0,1.0,1.0);
       glBegin(GL_POLYGON);
	        glVertex3fv(corners[0]);
			glVertex3fv(corners[1]);
			glVertex3fv(corners[2]);
			glVertex3fv(corners[3]);
	   glEnd();
   
	   glBegin(GL_QUADS);
	      glVertex3fv(corners[1]);
	      glVertex3fv(corners[2]);
	      glVertex3fv(corners[4]);
	      glVertex3fv(corners[5]);
	    glEnd();

		glBegin(GL_TRIANGLES);
	        glVertex3fv(corners[0]);
			glVertex3fv(corners[1]);
			glVertex3fv(corners[5]);
		glEnd();

		glBegin(GL_TRIANGLES);
	        glVertex3fv(corners[3]);
			glVertex3fv(corners[2]);
			glVertex3fv(corners[4]);
		glEnd();
}

  void stairs()

  {

   
   int i;
   

   for (i =0; i < 8; i++)
   {
	 OneStep();
	 glTranslatef(0, 2, -2);
	 glRotatef(25, 0,1,0);
   }
   
  }




static GLfloat theta[] = {0.0,0.0,0.0};
static GLint axis = 2;

void display(void)
{

 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glLoadIdentity();

	glRotatef(25, 1.0, 0.0, 0.0);
	
	glRotatef(theta[1], 0.0, 1.0, 0.0);
	

 stairs();

 glFlush();
	glutSwapBuffers();
}

void spinStairs()
{

/* Idle callback, spin cube 2 degrees about selected axis */

	theta[axis] += 2.0;
	if( theta[axis] > 360.0 ) theta[axis] -= 360.0;
	/* display(); */
	glutPostRedisplay();
}

void mouse(int btn, int state, int x, int y)
{

/* mouse callback, selects an axis about which to rotate */

	if(btn==GLUT_LEFT_BUTTON && state == GLUT_DOWN) theta[1]+=2;
	if(btn==GLUT_RIGHT_BUTTON && state == GLUT_DOWN)  glutIdleFunc(spinStairs);
	
	glutPostRedisplay();
}

void myReshape(int w, int h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    if (w <= h)
        glOrtho(-20.0, 20.0, -20.0 * (GLfloat) h / (GLfloat) w,
            20.0 * (GLfloat) h / (GLfloat) w, -20.0, 20.0);
    else
        glOrtho(-20.0 * (GLfloat) w / (GLfloat) h,
            20.0 * (GLfloat) w / (GLfloat) h, -20.0, 20.0, -20.0, 20.0);
    glMatrixMode(GL_MODELVIEW);
}

void
main(int argc, char **argv)
{
    glutInit(&argc, argv);

/* need both double buffering and z buffer */

    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(500, 500);
    glutCreateWindow("stairs");
    glutReshapeFunc(myReshape);
    glutDisplayFunc(display);
	   glutIdleFunc(NULL);
	   glutMouseFunc(mouse);
	   glEnable(GL_DEPTH_TEST); /* Enable hidden--surface--removal */
	   glClearColor(1.0, 1.0, 1.0, 1.0);
	   glColor3f(0.0, 0.0, 0.0);
	
    glutMainLoop();
}