#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 with current clearing color
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	// Save the matrix state and do the rotations
	glPushMatrix();
	glRotatef(45, 0.5f, 1.0f, 0.5f);

	glPushMatrix();
	glScalef(1.2, 0.7, 2.0);
	glColor3f(0.0, 0.0, 1.0);
	glutSolidCube(30);
	glPopMatrix();

	glPushMatrix();
	glTranslatef(0.0, 21.0, 0.0);
	glRotatef(yRot, 0.0f, 1.0f, 0.0f);
	glScalef(1.0, 0.7, 1.7);
	glColor3f(0.0, 1.0, 0.0);
	glutSolidCube(20);
	glPopMatrix();

	glPushMatrix();
	glRotatef(yRot, 0.0f, 1.0f, 0.0f);
	glTranslatef(0.0, 17.0, 15.0);
	glRotatef(xRot, 1.0f, 0.0f, 0.0f);
	glScalef(1.0, 1.0, 7.0);
	glTranslatef(0.0, 0.0, 2.5);
	glColor3f(1.0, 0.0, 0.0);
	glutSolidCube(5);
	glPopMatrix();

	// Restore the matrix state
	glPopMatrix();
	// Display the results
	glutSwapBuffers();
}

// This function does any needed initialization on the rendering
// context. 
void SetupRC()
{
	glEnable(GL_DEPTH_TEST);	// Hidden surface removal
	glFrontFace(GL_CCW);		// Counter clock-wise polygons face out
	glEnable(GL_CULL_FACE);		// Do not calculate inside of jet
	glShadeModel(GL_SMOOTH);

	glClearColor(1.0f, 1.0f, 1.0f, 1.0f );
}

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 > 10.0f)
		xRot = 10.0f;

	if(xRot < -50.0f)
		xRot = -50.0f;

	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 = 80.0f;
	// Prevent a divide by zero
	if(h == 0)
		h = 1;

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

	// Reset coordinate system
	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);

	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
}

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

	return 0;
}