#include <GL/glut.h> // (or others, depending on the system in use)
#include "sgi.h"


GLsizei w, h;
int width, height, depth;
unsigned char *image = NULL;
int Status;

void init(void);
void reshape(int w, int h);
void lineSegment(void);
void mainSelect(int);
void fileSelect(int);
void displaySelect(int);
void GrayScaleImage();
void NegativeImage(); //선언


void init(void)  {
	glClearColor(1.0, 1.0, 1.0, 0.0);       // Set display-window color to white.
	glMatrixMode(GL_PROJECTION); // Set projection parameters.
	gluOrtho2D(0.0, 200.0, 0.0, 150.0);
}

void reshape(int w, int h)
{
	glViewport(0, 0, (GLsizei)w, (GLsizei)h);
	height = (GLint)h;
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(0.0, (GLdouble)w, 0.0, (GLdouble)h);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
}


void display(void)
{

	glClear(GL_COLOR_BUFFER_BIT);
	glRasterPos2i(0, 0);

	glDrawPixels(width, height, GL_RGB,
		GL_UNSIGNED_BYTE, image);
	glFlush();
}

void mainSelect(int value)
{
	Status = value;
	switch (value) {
	case 666:
		printf("exit\n");
		exit(0);
		break;
	}
}

void fileSelect(int value)
{
	char *filename;
	Status = value;
	switch (value) {

	//이미지 추가하기.
	case 0:
		filename = "sample.rgb";
		image = read_sgi(filename, &width, &height, &depth);
		glutReshapeWindow(width, height);
		display();
		break;
	case 1:
		filename = "train.bmp";
		image = read_bmp(filename, &width, &height, &depth);
		glutReshapeWindow(width, height);
		display();
		break;
	case 2:
		filename = "desert.bmp";
		image = read_bmp(filename, &width, &height, &depth);
		glutReshapeWindow(width, height);
		display();
		break;
	}
}

void displaySelect(int value)
{
	Status = value;
	switch (value) {
	case 10:
		NegativeImage();
		display();
		break;
	}
}
//Negative 색상을 만들어 주는 코드. 이미지 색상값을 어떻게 주느냐에 따라 r,g,b color와 Negative lmage를 만들수 있음.
void NegativeImage() {
	int i, j;
	int r, g, b;
	for (j = 0; j<height; j++)  {
		for (i = 0; i<width * 3; i = i + 3) {
			r = image[j*width * 3 + i + 0];
			g = image[j*width * 3 + i + 1];
			b = image[j*width * 3 + i + 2];

			image[j*width * 3 + i + 2] = r;
			image[j*width * 3 + i + 1] = g;
			image[j*width * 3 + i + 0] = b;
		}
	}
}
//GrayScale 색상을 변환해주는 코드.
void GrayScaleImage() {
	int i, j, L;
	int r, g, b;
	for (j = 0; j<height; j++)  {
		for (i = 0; i<width * 3; i = i + 3) {
			r = image[j*width * 3 + i + 0];
			g = image[j*width * 3 + i + 1];
			b = image[j*width * 3 + i + 2];
			L=(0.30*image[j*width * 3 + i + 0]) +(0.59*image[j*width * 3 + i + 1])+(0.11*image[j*width * 3 + i+ 2]);
		}
	}

}


void main(int argc, char** argv)   {

	int fileMenu, displayMenu, mainMenu;

	glutInit(&argc, argv); 				// Initialize GLUT.
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); 	// Set display mode.
	//	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);


	glutInitWindowPosition(50, 100); 	// Set top-left display-window position.
	glutInitWindowSize(300, 300); 	// Set display-window width and height.
	glutCreateWindow("An Example OpenGL Program"); // Create display window.

	init(); 					// Execute initialization procedure.
	glutDisplayFunc(display); 	// Send graphics to display window.
	glutReshapeFunc(reshape);

	fileMenu = glutCreateMenu(fileSelect);
	glutAddMenuEntry("sample.rgb", 0);
	glutAddMenuEntry("train.bmp", 1);
	glutAddMenuEntry("desert.bmp", 2);

	displayMenu = glutCreateMenu(displaySelect);
	glutAddMenuEntry("Negative Image", 10);
	glutAddMenuEntry("GrayScale Image", 20); //메뉴바 생성 코드.

	mainMenu = glutCreateMenu(mainSelect);
	glutAddSubMenu("File", fileMenu);
	glutAddSubMenu("Display", displayMenu);

	glutAddMenuEntry("Quit", 666);
	glutSetMenu(mainMenu);
	glutAttachMenu(GLUT_RIGHT_BUTTON);

	glutMainLoop(); 		// Display everything and wait.
}