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




float angle=0.0,deltaAngle = 0.0,ratio;
float x=0.0f,y=1.75f,z=5.0f;
float lx=0.0f,ly=0.0f,lz=-1.0f;
GLint snowman_display_list;
int deltaMove = 0;


void changeSize(int w, int h)
	{

	// Prevent a divide by zero, when window is too short
	// (you cant make a window of zero width).
	if(h == 0)
		h = 1;

	ratio = 1.0f * w / h;
	// Reset the coordinate system before modifying
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	
	// Set the viewport to be the entire window
	glViewport(0, 0, w, h);

	// Set the clipping volume
	gluPerspective(45,ratio,1,1000);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	gluLookAt(x, y, z, 
		      x + lx,y + ly,z + lz,
			  0.0f,1.0f,0.0f);


	}


void drawSnowMan() {


	glColor3f(1.0f, 1.0f, 1.0f);

// Draw Body	
	glTranslatef(0.0f ,0.75f, 0.0f);
	glutSolidSphere(0.75f,20,20);


// Draw Head
	glTranslatef(0.0f, 1.0f, 0.0f);
	glutSolidSphere(0.25f,20,20);

// Draw Eyes
	glPushMatrix();
	glColor3f(0.0f,0.0f,0.0f);
	glTranslatef(0.05f, 0.10f, 0.18f);
	glutSolidSphere(0.05f,10,10);
	glTranslatef(-0.1f, 0.0f, 0.0f);
	glutSolidSphere(0.05f,10,10);
	glPopMatrix();

// Draw Nose
	glColor3f(1.0f, 0.5f , 0.5f);
	glRotatef(0.0f,1.0f, 0.0f, 0.0f);
	glutSolidCone(0.08f,0.5f,10,2);
}



GLuint createDL() {
	GLuint snowManDL;

	// Create the id for the list
	snowManDL = glGenLists(1);

	// start list
	glNewList(snowManDL,GL_COMPILE);

	// call the function that contains 
	// the rendering commands
		drawSnowMan();

	// endList
	glEndList();

	return(snowManDL);
}

void initScene() {

	glEnable(GL_DEPTH_TEST);
	snowman_display_list = createDL();

}

void orientMe(float ang) {


	lx = sin(ang);
	lz = -cos(ang);
	glLoadIdentity();
	gluLookAt(x, y, z, 
		      x + lx,y + ly,z + lz,
			  0.0f,1.0f,0.0f);
}


void moveMeFlat(int i) {
	x = x + i*(lx)*0.1;
	z = z + i*(lz)*0.1;
	glLoadIdentity();
	gluLookAt(x, y, z, 
		      x + lx,y + ly,z + lz,
			  0.0f,1.0f,0.0f);
}


void renderScene(void) {
  int i, j;

	if (deltaMove)
		moveMeFlat(deltaMove);
	if (deltaAngle) {
		angle += deltaAngle;
		orientMe(angle);
	}
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Draw ground

	glColor3f(0.9f, 0.9f, 0.9f);
	glBegin(GL_QUADS);
		glVertex3f(-100.0f, 0.0f, -100.0f);
		glVertex3f(-100.0f, 0.0f,  100.0f);
		glVertex3f( 100.0f, 0.0f,  100.0f);
		glVertex3f( 100.0f, 0.0f, -100.0f);
	glEnd();

// Draw 36 SnowMen

	for(i = -3; i < 3; i++) {
		for(j = -3; j < 3; j++) {
			glPushMatrix();
			glTranslatef(i*10.0,0,j * 10.0);
			glCallList(snowman_display_list);;
			glPopMatrix();
		}
  }

  glutSolidTeapot(1.5);
	glutSwapBuffers();
}

    
void pressKey(int key, int x, int y) {

	switch (key) {
		case GLUT_KEY_LEFT : 
			deltaAngle = -0.01f;break;
		case GLUT_KEY_RIGHT : 
			deltaAngle = 0.01f;break;
		case GLUT_KEY_UP : 
			deltaMove = 1;break;
		case GLUT_KEY_DOWN : 
			deltaMove = -1;break;
	}
}

void releaseKey(int key, int x, int y) {

	switch (key) {
		case GLUT_KEY_LEFT : 
		case GLUT_KEY_RIGHT : 
			deltaAngle = 0.0f;break;
		case GLUT_KEY_UP : 
		case GLUT_KEY_DOWN : 
			deltaMove = 0;break;
	}
}

    
int main(int argc, char **argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
	glutInitWindowPosition(100,100);
	glutInitWindowSize(640,360);
	glutCreateWindow("SnowMen from 3D-Tech");

	initScene();

	glutIgnoreKeyRepeat(1);
	glutSpecialFunc(pressKey);
	glutSpecialUpFunc(releaseKey);

	glutDisplayFunc(renderScene);
	glutIdleFunc(renderScene);

	glutReshapeFunc(changeSize);

	glutMainLoop();

	return(0);
}