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

//angle of rotation
float xpos = 0, ypos = 0, zpos = 0, xrot = 0, yrot = 0, angle=0.0;

float cRadius = 10.0f; // our radius distance from our character

float lastx, lasty;

//positions of the cubes
float positionz[10];
float positionx[10];

void cubepositions (void) { //set the positions of the cubes
	for (int i=0;i<10;i++)
	{
	positionz[i] = rand()%5 + 1;
	positionx[i] = rand()%5 + 1;
	}
}

//draw the cube
void cube (void) {
	for (int i=0;i<10 - 1;i++)
	{
	glPushMatrix();
	glTranslated(-positionx[i + 1] * 10, 0, -positionz[i + 1] * 10); //translate the cube
	glutSolidCube(2); //draw the cube
	glPopMatrix();
	}
}

void init (void) {
	cubepositions();
}

void enable (void) {
	glEnable (GL_DEPTH_TEST); //enable the depth testing
	glEnable (GL_LIGHTING); //enable the lighting
	glEnable (GL_LIGHT0); //enable LIGHT0, our Diffuse Light
	glEnable (GL_COLOR_MATERIAL);
	glShadeModel (GL_SMOOTH); //set the shader to smooth shader
}

void display (void) {
	glClearColor (0.0,0.0,0.0,1.0); //clear the screen to black
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); //clear the color buffer and the depth buffer
	enable();
    
	glLoadIdentity(); 
	
	glTranslatef(0.0f, 0.0f, -cRadius);
	glRotatef(xrot,1.0,0.0,0.0);
	glColor3f(1.0f, 0.0f, 0.0f);
	glutSolidCube(2); //Our character to follow
	
	glRotatef(yrot,0.0,1.0,0.0);  //rotate our camera on the y-axis (up and down)
	glTranslated(-xpos,0.0f,-zpos); //translate the screen to the position of our camera
	glColor3f(1.0f, 1.0f, 1.0f);
	cube(); //call the cube drawing function

	glutSwapBuffers(); //swap the buffers
	angle++; //increase the angle
}

void reshape (int w, int h) {
	glViewport (0, 0, (GLsizei)w, (GLsizei)h); //set the viewport to the current window specifications
	glMatrixMode (GL_PROJECTION); //set the matrix to projection
	glLoadIdentity ();
	gluPerspective (60, (GLfloat)w / (GLfloat)h, 0.1, 100.0); //set the perspective (angle of sight, width, height, , depth)
	glMatrixMode (GL_MODELVIEW); //set the matrix back to model
}

void keyboard (unsigned char key, int x, int y) {
	if (key=='q')
	{
	xrot += 1;
	if (xrot >360) xrot -= 360;
	}

	if (key=='z')
	{
	xrot -= 1;
	if (xrot < -360) xrot += 360;
	}

	if (key=='w')
	{
	float xrotrad, yrotrad;
	yrotrad = (yrot / 180 * 3.141592654f);
	xrotrad = (xrot / 180 * 3.141592654f); 
	xpos += float(sin(yrotrad));
	zpos -= float(cos(yrotrad));
	ypos -= float(sin(xrotrad));
	}

	if (key=='s')
	{
	float xrotrad, yrotrad;
	yrotrad = (yrot / 180 * 3.141592654f);
	xrotrad = (xrot / 180 * 3.141592654f); 
	xpos -= float(sin(yrotrad));
	zpos += float(cos(yrotrad));
	ypos += float(sin(xrotrad));
	}

	if (key=='d')
	{
    float yrotrad;
	yrotrad = (yrot / 180 * 3.141592654f);
	xpos += float(cos(yrotrad)) * 0.2;
	zpos += float(sin(yrotrad)) * 0.2;
	}

	if (key=='a')
	{
	float yrotrad;
	yrotrad = (yrot / 180 * 3.141592654f);
	xpos -= float(cos(yrotrad)) * 0.2;
	zpos -= float(sin(yrotrad)) * 0.2;
	}

	if (key==27)
	{
	exit(0);
	}
}

void mouseMovement(int x, int y) {
	int diffx=x-lastx; //check the difference between the current x and the last x position
	int diffy=y-lasty; //check the difference between the current y and the last y position
	lastx=x; //set lastx to the current x position
	lasty=y; //set lasty to the current y position
	xrot += (float) diffy; //set the xrot to xrot with the addition of the difference in the y position
	yrot += (float) diffx;	//set the xrot to yrot with the addition of the difference in the x position
}

int main (int argc, char **argv) {
    glutInit (&argc, argv);
	glutInitDisplayMode (GLUT_DOUBLE | GLUT_DEPTH); 
	glutInitWindowSize (500, 500); 
	glutInitWindowPosition (100, 100);
    glutCreateWindow ("A basic OpenGL Window"); 
	init (); 
    glutDisplayFunc (display); 
	glutIdleFunc (display); 
	glutReshapeFunc (reshape); 

	glutPassiveMotionFunc(mouseMovement); //check for mouse movement

	glutKeyboardFunc (keyboard); 
    glutMainLoop (); 
    return 0;
}