/*
 * (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 * Unpublished-- rights reserved under the copyright laws of the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.
 */
/*
 *  picksquare.c
 *  Use of multiple names and picking are demonstrated.  
 *  A 3x3 grid of squares is drawn.  When the left mouse 
 *  button is pressed, all squares under the cursor position 
 *  have their color changed.
 */
#include <GL/gl.h>
#include <GL/glu.h>
#include <stdio.h>
#include <stdlib.h>
#include <GL/glaux.h>

int board[3][3];							       /*

									        * amount of color for each square      
									        */

/*
 * Clear color value for every square on the board          
 */
void myinit(void)
{
  int i, j;

  for (i = 0; i < 3; i++)
    for (j = 0; j < 3; j++)
      board[i][j] = 0;
  glClearColor(0.0, 0.0, 0.0, 0.0);
}

/*
 * The nine squares are drawn.  In selection mode, each 
 * *  square is given two names:  one for the row and the 
 * *  other for the column on the grid.  The color of each 
 * *  square is determined by its position on the grid, and 
 * *  the value in the board[][] array.
 */
void drawSquares(GLenum mode)
{
  GLuint i, j;

  for (i = 0; i < 3; i++) {
    if (mode == GL_SELECT)
      glLoadName(i);
    for (j = 0; j < 3; j++) {
      if (mode == GL_SELECT)
	glPushName(j);
      glColor3f((GLfloat) i / 3.0, (GLfloat) j / 3.0,
		(GLfloat) board[i][j] / 3.0);
      glRecti(i, j, i + 1, j + 1);
      if (mode == GL_SELECT)
	glPopName();
    }
  }
}

/*
 * processHits() prints out the contents of the 
 * *  selection array.
 */
void processHits(GLint hits, GLuint buffer[])
{
  unsigned int i, j;
  GLuint ii, jj, names, *ptr;

  printf("hits = %d\n", hits);
  ptr = (GLuint *) buffer;
  for (i = 0; i < hits; i++) {						       /*
									        * for each hit  
									        */
    names = *ptr;
    printf(" number of names for this hit = %d\n", names);
    ptr++;
    printf("  z1 is %u;", *ptr);
    ptr++;
    printf(" z2 is %u\n", *ptr);
    ptr++;
    printf("   names are ");
    for (j = 0; j < names; j++) {					       /*
									        * for each name 
									        */
      printf("%d ", *ptr);
      if (j == 0)							       /*
									        * set row and column  
									        */
	ii = *ptr;
      else if (j == 1)
	jj = *ptr;
      ptr++;
    }
    printf("\n");
    board[ii][jj] = (board[ii][jj] + 1) % 3;
  }
}

/*
 * pickSquares() sets up selection mode, name stack, 
 * *  and projection matrix for picking.  Then the 
 * *  objects are drawn.
 */
#define BUFSIZE 512

void pickSquares(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();
/*
 * create 5x5 pixel picking region near cursor location 
 */
  gluPickMatrix((GLdouble) x, (GLdouble) (viewport[3] - y),
		5.0, 5.0, viewport);
  gluOrtho2D(0.0, 3.0, 0.0, 3.0);
  drawSquares(GL_SELECT);

  glMatrixMode(GL_PROJECTION);
  glPopMatrix();
  glFlush();

  hits = glRenderMode(GL_RENDER);
  processHits(hits, selectBuf);
}

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

void myReshape(int w, int h)
{
  glViewport(0, 0, w, h);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluOrtho2D(0.0, 3.0, 0.0, 3.0);
  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, pickSquares);
  auxReshapeFunc(myReshape);
  auxMainLoop(display);
  return 0;
}