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

// Define a constant for the value of PI
#define GL_PI 3.1415f

// Rotation amounts
static GLfloat xRot = 0.0f;
static GLfloat yRot = 0.0f;

// Called to draw scene
void RenderScene(void)
{
	// Clear the window and the depth buffer
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

	// Save matrix state and do the rotation
	glPushMatrix();

	glRotatef(xRot, 1.0f, 0.0f, 0.0f);
	glRotatef(yRot, 0.0f, 1.0f, 0.0f);

	glPushMatrix();
	glTranslatef(15.0, 0.0, 0.0);
	glutSolidCube(10.0f);
	glPopMatrix();

	glPushMatrix();
	glTranslatef(-15.0, 0.0, 0.0);
	glutSolidCube(10.0f);
	glPopMatrix();

	glPushMatrix();
	glTranslatef(0.0, 0.0, 15.0);
	glutSolidCube(10.0f);
	glPopMatrix();

	glPushMatrix();
	glTranslatef(0.0, 0.0, -15.0);
	glutSolidCube(10.0f);
	glPopMatrix();

	// Restore transformations
	glPopMatrix();

	// Flush drawing commands
	glutSwapBuffers();
	}

// This function does any needed initialization on the rendering
// context. 
void SetupRC()
{
	// Black background
	glClearColor(0.0f, 0.0f, 0.0f, 1.0f );

	// Set drawing color to green
	glColor3f(0.0f, 1.0f, 0.0f);

	// Set color shading model to flat
	glShadeModel(GL_FLAT);

	glEnable(GL_DEPTH_TEST);

}

void SpecialKeys(int key, int x, int y)
{
	if(key == GLUT_KEY_UP)
		xRot-= 5.0f;

	if(key == GLUT_KEY_DOWN)
		xRot += 5.0f;

	if(key == GLUT_KEY_LEFT)
		yRot -= 5.0f;

	if(key == GLUT_KEY_RIGHT)
		yRot += 5.0f;

	if(xRot > 356.0f)
		xRot = 0.0f;

	if(xRot < -1.0f)
		xRot = 355.0f;

	if(yRot > 356.0f)
		yRot = 0.0f;

	if(yRot < -1.0f)
		yRot = 355.0f;

	// Refresh the Window
	glutPostRedisplay();
}

void ChangeSize(int w, int h)
{
	GLfloat nRange = 25.0f;

	// Prevent a divide by zero
	if(h == 0)
		h = 1;

	// Set Viewport to window dimensions
    glViewport(0, 0, w, h);

	// Reset projection matrix stack
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();

	// Establish clipping volume (left, right, bottom, top, near, far)
    if (w <= h) 
		glOrtho (-nRange, nRange, -nRange*h/w, nRange*h/w, -nRange, nRange);
    else 
		glOrtho (-nRange*w/h, nRange*w/h, -nRange, nRange, -nRange, nRange);

	// Reset Model view matrix stack
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
}

int main(int argc, char* argv[])
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
	glutCreateWindow("Kockak");
	glutReshapeFunc(ChangeSize);
	glutSpecialFunc(SpecialKeys);
	glutDisplayFunc(RenderScene);
	SetupRC();
	glutMainLoop();

	return 0;
}