/* transparent teapot demo by Ingemar Ragnemalm*/

#ifdef __APPLE__
	#include <GLUT/glut.h>
//	#include <OpenGL/gl.h>
#else
	#include <GL/glut.h>
//	#include <GL/gl.h>
#endif
#include <math.h>

GLfloat angle = 0.0;

// For file management
#include <stdio.h>
#include <stdlib.h>

int setting = 1;

void display()
{
	GLfloat s = sin(angle);
	GLfloat c = cos(angle);
	
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	
	glMatrixMode(GL_MODELVIEW);

	// Save the current state
	glPushMatrix();
	
	glRotatef(angle, 1,1,1);
	glScalef(-1, 1, 1); // Teapot is inside out

// 3 cases: no culling, culling and draw fronts, culling and draw first backs, then fronts

	glDisable(GL_CULL_FACE);
//	glEnable(GL_CULL_FACE);
	glCullFace(GL_FRONT); //
	glutSolidTeapot(1); //
	glCullFace(GL_BACK);
	glutSolidTeapot(1);
	
	glPopMatrix();
	
	glutSwapBuffers();
}

void timer(int i)
{
	angle += 1.0;
	glutTimerFunc(20, timer, i);
	glutPostRedisplay();
}

void keyboard(unsigned char key, int x, int y)
{
	switch (key)
	{
	case 27:
		exit(0);
	case '1':
		setting = 1; break;
	case '2':
		setting = 2; break;
	case '3':
		setting = 3; break;
	}
}

void reshape(int w, int h)
{
	glViewport (0, 0, (GLsizei) w, (GLsizei) h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glFrustum(-0.7, 0.7, -0.7, 0.7, 1, 20);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	gluLookAt(0,0,3, 0,0,0, 0,1,0); // camera, look-at-point, up-vector
}

	GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 1.0 };
	GLfloat mat_shininess[] = { 10.0 };
	GLfloat light_position[] = { 1.0, 1.0, 2.0, 0.0 }; // ljuset gŒr frŒn det hŒllet?

// A simple texture
	GLubyte minitex4[4][4][3] =
	{
		{ {255,  0,255}, {  0,  0,255}, {  0,  0,255}, {  0,255,255}},
		{ {  0,  0,255}, {255,  0,255}, {  0,255,255}, {  0,  0,255}},
		{ {  0,  0,255}, {  0,255,255}, {255,  0,255}, {  0,  0,255}},
		{ {  0,255,255}, {  0,  0,255}, {  0,  0,255}, {255,  0,255}},
	};

// Texture with transparency
	GLubyte minitexrgba[4][4][4] =
	{
		{ {255,  0,255, 255}, {  0,  0,255, 128}, {  0,  0,255, 128}, {  0,255,255, 255}},
		{ {  0,  0,255, 128}, {255,  0,255, 0}, {  0,255,255, 0}, {  0,  0,255, 128}},
		{ {  0,  0,255, 128}, {  0,255,255, 0}, {255,  0,255, 0}, {  0,  0,255, 128}},
		{ {  0,255,255, 255}, {  0,  0,255, 128}, {  0,  0,255, 128}, {255,  0,255, 255}},
	};

	GLfloat planeS[] = {2.5, 0.0, 0.0, 0.5};
	GLfloat planeT[] = {0.0, 0.0, 2.5, 0.5};
	

int main(int argc, char **argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH);
	glutInitWindowSize(500, 500);
	glutCreateWindow("simple9");
	
	// Set the background color
	glClearColor(0.5, 0.7, 0.5, 0);
	glClearColor(1.0, 1.0, 1.0, 0);
	
	// Various initializations, enable OpenGL features
	glShadeModel(GL_SMOOTH);
//	glEnable(GL_CULL_FACE);
	glCullFace(GL_BACK);

// ***********
	glCullFace(GL_FRONT);
	glEnable(GL_DEPTH_TEST);
// ***********
	
	glEnable(GL_BLEND);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	
	
	glEnable(GL_NORMALIZE); // if we can't guarantee normal vectors to have unit length
	
	// Turn on the light
	glEnable(GL_LIGHTING);
	glEnable(GL_LIGHT0);
//	glLightModeli(GL_LIGHT_MODEL_TWO_SIDE, GL_TRUE);
	
	glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
	glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);
	glLightfv(GL_LIGHT0, GL_POSITION, light_position);
	
	glEnable(GL_TEXTURE_2D);
	
	// Install textures
//	glTexImage2D(GL_TEXTURE_2D, 0, 3, 4, 4, 0, GL_RGB, GL_UNSIGNED_BYTE, minitex4);
//	glTexImage2D(GL_TEXTURE_2D, 0, 3, 2, 2, 0, GL_RGB, GL_UNSIGNED_BYTE, minitex2);
	
	glTexImage2D(GL_TEXTURE_2D, 0, 4, 4, 4, 0, GL_RGBA, GL_UNSIGNED_BYTE, minitexrgba);
	
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
//	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	
	glEnable(GL_TEXTURE_GEN_S);
	glEnable(GL_TEXTURE_GEN_T);
	glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
	glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
	
	glTexGenfv(GL_S, GL_OBJECT_PLANE, planeS);
	glTexGenfv(GL_S, GL_OBJECT_PLANE, planeT);
	
	// Install GLUT callback functions
	glutDisplayFunc(display);
	glutReshapeFunc(reshape);
	glutTimerFunc(20, timer, 0);
	glutKeyboardFunc(keyboard);
	
	// Run!
	glutMainLoop();
	return 0;
}