/*
 * (c) Copyright 1993, Silicon Graphics, Inc.
 * ALL RIGHTS RESERVED 
 * Permission to use, copy, modify, and distribute this software for 
 * any purpose and without fee is hereby granted, provided that the above
 * copyright notice appear in all copies and that both the copyright notice
 * and this permission notice appear in supporting documentation, and that 
 * the name of Silicon Graphics, Inc. not be used in advertising
 * or publicity pertaining to distribution of the software without specific,
 * written prior permission. 
 *
 * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
 * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
 * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
 * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
 * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
 * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
 * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
 * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
 * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
 * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
 * 
 * US Government Users Restricted Rights 
 * Use, duplication, or disclosure by the Government is subject to
 * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
 * (c)(1)(ii) of the Rights in Technical Data and Computer Software
 * clause at DFARS 252.227-7013 and/or in similar or successor
 * clauses in the FAR or the DOD or NASA FAR Supplement.
 * Unpublished-- rights reserved under the copyright laws of the
 * United States.  Contractor/manufacturer is Silicon Graphics,
 * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
 *
 * OpenGL(TM) is a trademark of Silicon Graphics, Inc.
 */
/*
 *  pickline.c
 *  Picking is demonstrated here.  Press the left mouse button
 *  is enter picking mode.  You get two hits if you press the
 *  mouse, while the cursor is where the lines intersect.
 */
#include <GL/gl.h>
#include <GL/glu.h>
#include <stdio.h>
#include <stdlib.h>
#include "glaux.h"

void drawLine(GLenum mode)
{
    if (mode == GL_SELECT)
	glLoadName (1);
    glBegin (GL_LINES);
    glColor3f (1.0, 1.0, 1.0);
    glVertex3f (30.0, 30.0, 0.0);
    glVertex3f (50.0, 60.0, 0.0);
    glEnd (); 

    if (mode == GL_SELECT)
	glLoadName (2);
    glBegin (GL_LINES);
    glColor3f (1.0, 1.0, 1.0);
    glVertex3f (50.0, 60.0, 0.0);
    glVertex3f (70.0, 40.0, 0.0);
    glEnd (); 
}

/*  pickline() is called when the mouse is pressed.
 *  The projection matrix is reloaded to include the
 *  picking matrix.  The line is "redrawn" during
 *  selection mode, and names are sent to the buffer.
 */
#define BUFSIZE 512

void pickLine(AUX_EVENTREC *event)
{
    GLuint selectBuf[BUFSIZE];
    GLint hits;
    GLint viewport[4];
    int x, y;

    x = event->data[AUX_MOUSEX];
    y = event->data[AUX_MOUSEY];
    glGetIntegerv (GL_VIEWPORT, viewport);

    glSelectBuffer (BUFSIZE, selectBuf);
    (void) glRenderMode (GL_SELECT);

    glInitNames();
    glPushName(-1);

    glMatrixMode (GL_PROJECTION);
    glPushMatrix ();
    glLoadIdentity ();
    gluPickMatrix ((GLdouble) x, (GLdouble) (viewport[3] - y), 
	5.0, 5.0, viewport);
    gluOrtho2D (0.0, (GLdouble) viewport[2], 
	0.0, (GLdouble) viewport[3]);
    drawLine (GL_SELECT);
    glPopMatrix ();
    glFlush ();

    hits = glRenderMode (GL_RENDER);
    printf ("hits is %d\n", hits);
} 

void myinit (void) 
{
    glShadeModel (GL_FLAT);
    glClearColor (0.0, 0.0, 0.0, 0.0);
}

void display(void)
{
    glClear(GL_COLOR_BUFFER_BIT);
    drawLine (GL_RENDER);
    glFlush();
}

void myReshape(int w, int h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D (0.0, (GLdouble) w, 0.0, (GLdouble) h);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

/*  Main Loop
 *  Open window with initial window size, title bar, 
 *  RGBA display mode, and handle input events.
 */
int main(int argc, char** argv)
{
    auxInitDisplayMode (AUX_SINGLE | AUX_RGB);
    auxInitPosition (0, 0, 100, 100);
    if (!auxInitWindow (argv[0]))
       auxQuit();
    myinit ();
    auxMouseFunc (AUX_LEFTBUTTON, AUX_MOUSEDOWN, pickLine);
    auxReshapeFunc (myReshape);
    auxMainLoop(display);
    return 0;
}
