// From a tutorial by Donald Shannon Urquhart
//
//fullscreen mode in GLUT is probably one of the easiest things you can do
//just before you call the line to enter fullscreen mode you choose
//which settings to use when in fullscreen mode. Such as the resolution,
//color depth and the refresh rate.
//we do this with:
//glutGameModeString( "1024x768:32@75" );
//this is setting the resolution to 1024x768, you can also use 800x600, 640x480, etc
//next it is saying to use a color depth of 32 bits, you can also use 24, 16, 8, etc
//then it is telling the program to run the screen refresh rate at 75hertz, others are 65, 70, 80, 85, etc
//after that when then tell GLUT to enter the fullscreen mode which it callse Game Mode.
//we do this with:
//glutEnterGameMode();
//then when we want to exit the program we say:
//glutLeaveGameMode(); to set the screen back to how it was

//and that was it. simple wasn't it?

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

/* Minimum stack space */
static USED const char *stack = "$STACK:65535"; 

//angle of rotation
float xpos = 0, ypos = 0, zpos = 0, xrot = 0, yrot = 90, angle=0.0;

//draw the cubes, they make a fancy shape from above :P
void cube (void) {
	float i;
	for (i=0;i<50;i++)
	{
	glTranslated(1, 0, 1);
	glPushMatrix();
	glutSolidCube(2); //draw the cube
	glPopMatrix();
	}
}

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

void camera (void) {
	glRotatef(xrot,1.0,0.0,0.0); 
	glRotatef(yrot,0.0,1.0,0.0); 
	glTranslated(-xpos,-ypos,-zpos); 
}

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
    glLoadIdentity();  
	gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); //camera position, x,y,z, looking at x,y,z, Up Positions of the camera
	camera();
	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, 1.0, 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')
	{
	yrot += 1;
	if (yrot >360) yrot -= 360;
	}

	if (key=='a')
	{
	yrot -= 1;
	if (yrot < -360)yrot += 360;
	}
	if (key==27)
	{
	glutLeaveGameMode(); //set the resolution how it was
	exit(0); //quit the program
	}
}

int main (int argc, char **argv) {
    glutInit (&argc, argv);
	glutInitDisplayMode (GLUT_DOUBLE | GLUT_DEPTH); //set the display to Double buffer, with depth
	glutGameModeString( "1024x768:32@75" ); //the settings for fullscreen mode
	glutEnterGameMode(); //set glut to fullscreen using the settings in the line above
	init (); //call the init function
    glutDisplayFunc (display); //use the display function to draw everything
	glutIdleFunc (display); //update any variables in display, display can be changed to anyhing, as long as you move the variables to be updated, in this case, angle++;
	glutReshapeFunc (reshape); //reshape the window accordingly
	glutKeyboardFunc (keyboard); //check the keyboard
	glutMainLoop (); //call the main loop
    return 0;
}