// Developed by Neil Kemp: http://neilkemp.us
// Licensed under the MIT license: http://www.opensource.org/licenses/mit-license.php


// GL includes
// ----------------------------------------------------------------
#include <OpenGL/gl.h>
#include <OpenGL/glu.h>
#include <GLUT/glut.h>
#include <stdlib.h>



// Window defines
// ----------------------------------------------------------------
#define WINDOW_WIDTH	800
#define WINDOW_HEIGHT	600

#ifndef BOOL
	#define BOOL	int
	#define FALSE	0
	#define TRUE	1
#endif


// Function prototypes
// ----------------------------------------------------------------
BOOL						initialize_gl(void);
BOOL						initialize_resources(void);
void						free_resources(void);
BOOL						on_render_frame(void);
void						on_size_window(int width, int height);


// GLUT callback unction prototypes
// ----------------------------------------------------------------
void						draw_glut_frame(void);
void						resize_glut(int width, int height);
void						process_normal_keys(unsigned char key, int x, int y);
void						process_special_keys(int key, int x, int y);


// Entry point
// ----------------------------------------------------------------
int main(int argc, char** argv)
{
	// Initialize GLUT
	glutInit(&argc, argv);
	glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_MULTISAMPLE);
	glutInitWindowSize (WINDOW_WIDTH, WINDOW_HEIGHT);
	glutInitWindowPosition (100, 100);
	glutCreateWindow (argv[0]);

	glutSetWindowTitle("Project Name (OSX:OpenGL) - ESC to Exit");

	// Initialize GL settings
	if(!initialize_gl())
	{	return -1;
	}	

	// Initialize resources
	if(!initialize_resources())
	{	free_resources();
		return 0;
	}

	// Set GLUT callbacks
	glutDisplayFunc(draw_glut_frame);
	glutIdleFunc(draw_glut_frame);
	glutReshapeFunc(resize_glut);
	glutKeyboardFunc(process_normal_keys);
	glutSpecialFunc(process_special_keys);

	// Start GLUT loop
	glutMainLoop();

	// Shutdown
	free_resources();	

	return 0;
}

// Initialize OpenGL settings
BOOL initialize_gl(void)
{
	// Local data
	float			gl_float4[4];


	// Setup perspective matrix
	on_size_window(WINDOW_WIDTH, WINDOW_HEIGHT);
	
	// Set OpenGL defaults
	glClearColor	(0.05f, 0.1f, 0.2f, 1.0f);
	glClearDepth	(1.0f);
	glEnable		(GL_DEPTH_TEST);
	glDepthFunc		(GL_LEQUAL);
	glShadeModel	(GL_SMOOTH );
	glHint			(GL_POLYGON_SMOOTH_HINT, GL_NICEST);
	glHint			(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
	glHint			(GL_LINE_SMOOTH_HINT, GL_NICEST);
	glEnable		(GL_CULL_FACE);
	glFrontFace		(GL_CCW);
	glCullFace		(GL_BACK);
	glEnable		(GL_TEXTURE_2D);	
	glEnable		(GL_LIGHTING);
	glEnable		(GL_MULTISAMPLE); 

	// Set ambient lighting
	gl_float4[0] = 0.9f;	gl_float4[1] = 0.9f;	gl_float4[2] = 0.9f;	gl_float4[3] = 1.0f;
	glLightModelfv(GL_LIGHT_MODEL_AMBIENT, gl_float4);

	return TRUE;
}

// Initialize application resources
BOOL initialize_resources(void)
{
	// TODO

	return TRUE;
}

// Free resources
void free_resources(void)
{
	// TODO
}

// Called once per render frame
BOOL on_render_frame(void)
{
	// Clear
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

		// TODO Draw
	
	// Swap buffers
	glutSwapBuffers();

	return TRUE;
}

// Called when window is resized
void on_size_window(int width, int height)
{
	if(height <= 0)
	{	height = 1;
	}
	// Change viewport size
	glViewport(0,0, width, height);

	// Set projection matrix
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(45.0f, (GLfloat)width / (GLfloat)height, 0.1f, 1000.0f);

	// TODO Setup camera
	/*
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();	
	gluLookAt(camera_position.x, camera_position.y, camera_position.z, 
			  camera_look_at.x, camera_look_at.y, camera_look_at.z, 
			  0, 1, 0);
	*/
}

// GLUT callback functions
// ----------------------------------------------------------------
// Draw frame
void draw_glut_frame(void)
{	
	if(!on_render_frame())
	{	exit(0);
	}
}
// Resize GLUT window
void resize_glut(int width, int height)
{	
	on_size_window(width, height);
}
// Process normal GLUT keys
void process_normal_keys(unsigned char key, int x, int y)
{
	// Exit on ESC
	if(key == 27) 
	{	exit(0);
	}
}
// Process special GLUT keys
void process_special_keys(int key, int x, int y)
{	
	// Check for left arrow		
	if(key == GLUT_KEY_LEFT) // LEFT
	{
	}	
	// Check for right arrow		
	if(key == GLUT_KEY_RIGHT) // RIGHT
	{		
	}	
	// Check for up arrow		
	if(key == GLUT_KEY_UP) // UP
	{			
	}	
	// Check for down arrow		
	if(key == GLUT_KEY_DOWN) // DOWN
	{
	}	
}