#include <windows.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <SDL/SDL.h>
#include <math.h>
#include <iostream>

#pragma comment(lib,"OpenGL32.lib")
#pragma comment(lib,"GLu32.lib")
#pragma comment(lib,"SDLmain.lib")
#pragma comment(lib,"SDL.lib")


const double PI=3.14159;
const int SCREEN_WIDTH=800;
const int SCREEN_HEIGHT=600;
const int SCREEN_BPP=32;
const char titre[30]="Picking";
const int BUFSIZE=512;

void initGL()
{
	//on vide les tampons de profondeur et chromatique
	glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
	//on met le fond de la fenetre en noir
	glClearColor(0.0f,0.0f,0.0f,0.0f);
	//On règle le point de vue
	glViewport(0,0,SCREEN_WIDTH,SCREEN_HEIGHT);
	//on initialise notre matrice de projection
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	//on est en projection orthogonale
	gluOrtho2D(0,SCREEN_WIDTH,0,SCREEN_HEIGHT);
	// idem avec la matrice de vue
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	
}
void processHits (GLint hits, GLuint buffer[])
{
   int i, j;
   GLuint names, *ptr;
   GLuint id;
   printf ("hits = %d\n", hits);
   ptr = (GLuint *) buffer;


   for (i = 0; i <  hits; i++) {	/*  for each hit  */
	       id = buffer[(i<<2)+3];
   printf("Nom du hit=%d",id);
      names = *ptr;
      printf (" number of names for this hit = %d\n", names); ptr++;
      printf("  z1 is %g;", (float) *ptr/0x7fffffff); ptr++;
      printf(" z2 is %g\n", (float) *ptr/0x7fffffff); ptr++;
      printf ("   names are ");
      for (j = 0; j < (int)names; j++) { /*  for each name */
         printf ("%d ", *ptr);
         
      }
      printf ("\n");

   }
}

void affiche_carre()
{
	glLoadName(1);
	glColor3f(1,0,0);
	glBegin(GL_QUADS);
		glVertex2i(0,0);
		glVertex2i(0,SCREEN_HEIGHT/2);
		glVertex2i(SCREEN_WIDTH/2,SCREEN_HEIGHT/2);
		glVertex2i(SCREEN_WIDTH/2,0);
	glEnd();

	glLoadName(2);
	glColor3f(1,1,1);
	glBegin(GL_QUADS);
		glVertex2i(SCREEN_WIDTH/2,0);
		glVertex2i(SCREEN_WIDTH/2,SCREEN_HEIGHT/2);
		glVertex2i(SCREEN_WIDTH,SCREEN_HEIGHT/2);
		glVertex2i(SCREEN_WIDTH,0);
	glEnd();

	glLoadName(3);
	glColor3f(0,1,0);
	glBegin(GL_QUADS);
		glVertex2i(SCREEN_WIDTH/2,SCREEN_HEIGHT/2);
		glVertex2i(SCREEN_WIDTH/2,SCREEN_HEIGHT);
		glVertex2i(SCREEN_WIDTH,SCREEN_HEIGHT);
		glVertex2i(SCREEN_WIDTH,SCREEN_HEIGHT/2);
	glEnd();

	glLoadName(4);
	glColor3f(0,0,1);
	glBegin(GL_QUADS);
		glVertex2i(0,SCREEN_HEIGHT/2);
		glVertex2i(0,SCREEN_HEIGHT);
		glVertex2i(SCREEN_WIDTH/2,SCREEN_HEIGHT);
		glVertex2i(SCREEN_WIDTH/2,SCREEN_HEIGHT/2);
	glEnd();

}


void pick(int x,int y)
{
	GLuint selectBuf[BUFSIZE];
	GLint hits;
	GLint viewport[4];

	glGetIntegerv(GL_VIEWPORT, viewport);
	glSelectBuffer(BUFSIZE,selectBuf);

	//on passe en mode selection
	glRenderMode(GL_SELECT);
	//on initialise la pile de noms
	glInitNames();
	//on empile qqchose dans la matrice de noms sinon erreur avec le glLoadName
	glPushName(0);

	glMatrixMode (GL_PROJECTION);
	glPushMatrix ();	/* push projection */
	glLoadIdentity ();

	gluPickMatrix ((GLdouble) x, (GLdouble) (viewport[3] - y), 5.0, 5.0, viewport);

	gluOrtho2D(0,SCREEN_WIDTH,0,SCREEN_HEIGHT);
	//on empile les 4 carrées dans la matrice de noms
	affiche_carre();
	glPopMatrix();

	glFlush();
	glMatrixMode(GL_MODELVIEW);
	glPushMatrix();		/* push modelview */
	glLoadIdentity();

	//on voit les differents hits atteint
	hits = glRenderMode(GL_RENDER);
	processHits (hits, selectBuf);


}

int main(int argc, char **argv)
{
	SDL_Surface *screen=NULL;
	SDL_Event event;
	bool fini=false;

	//initialisation de la SDL
	if(SDL_Init(SDL_INIT_VIDEO) == -1)
	{
		std::cout<<"L'initialisation de la SDL a echoue!"<<std::endl;
		return EXIT_FAILURE;
	}
	atexit(SDL_Quit);
	//initialisation du fenetrage
	screen=SDL_SetVideoMode(SCREEN_WIDTH,SCREEN_HEIGHT,SCREEN_BPP,SDL_OPENGL);
	if(screen == NULL)
	{
		std::cout<<"Impossible d'ouvrir le mode video de la SDL"<<std::endl;
		return EXIT_FAILURE;
	}
	SDL_WM_SetCaption(titre,NULL);
	
	SDL_ShowCursor(TRUE);
	initGL();

	while(!fini)
	{	
		while(SDL_PollEvent(&event))
		{
			switch(event.type)
			{
				case SDL_QUIT:		
					fini=true;
					break;

				case SDL_MOUSEBUTTONUP:
					pick(event.button.x,event.button.y);
					break;
				default: break;
			}
		}
		
		affiche_carre();
		glFlush();
		SDL_GL_SwapBuffers();
	}
	SDL_Quit();
	return EXIT_SUCCESS;
}