/* * Copyright (c) 1993-1997, 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 * Unpublished-- rights reserved under the copyright laws of the * United States.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(R) is a registered trademark of Silicon Graphics, Inc. *//* * pickdepth.c * Picking is demonstrated in this program.  In  * rendering mode, three overlapping rectangles are  * drawn.  When the left mouse button is pressed,  * selection mode is entered with the picking matrix.   * Rectangles which are drawn under the cursor position * are "picked."  Pay special attention to the depth  * value range, which is returned. */#include <GL/glut.h>#include <stdlib.h>#include <stdio.h>void init(void){   glClearColor(0.0, 0.0, 0.0, 0.0);   glEnable(GL_DEPTH_TEST);   glShadeModel(GL_FLAT);   glDepthRange(0.0, 1.0);  /* The default z mapping */}/* The three rectangles are drawn.  In selection mode,  * each rectangle is given the same name.  Note that  * each rectangle is drawn with a different z value. */void drawRects(GLenum mode){   if (mode == GL_SELECT)      glLoadName(1);   glBegin(GL_QUADS);   glColor3f(1.0, 1.0, 0.0);   glVertex3i(2, 0, 0);   glVertex3i(2, 6, 0);   glVertex3i(6, 6, 0);   glVertex3i(6, 0, 0);   glEnd();   if (mode == GL_SELECT)      glLoadName(2);   glBegin(GL_QUADS);   glColor3f(0.0, 1.0, 1.0);   glVertex3i(3, 2, -1);   glVertex3i(3, 8, -1);   glVertex3i(8, 8, -1);   glVertex3i(8, 2, -1);   glEnd();   if (mode == GL_SELECT)      glLoadName(3);   glBegin(GL_QUADS);   glColor3f(1.0, 0.0, 1.0);   glVertex3i(0, 2, -2);   glVertex3i(0, 7, -2);   glVertex3i(5, 7, -2);   glVertex3i(5, 2, -2);   glEnd();}/*  processHits() prints out the contents of the  *  selection array. */void processHits(GLint hits, GLuint buffer[]){   unsigned int i, j;   GLuint 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 hit = %d\n", names); ptr++;      printf("  z1 is %g;", (float) *ptr/0x7fffffff); ptr++;      printf(" z2 is %g\n", (float) *ptr/0x7fffffff); ptr++;      printf("   the name is ");      for (j = 0; j < names; j++) {  /* for each name */         printf("%d ", *ptr); ptr++;      }      printf("\n");   }}/*  pickRects() sets up selection mode, name stack,  *  and projection matrix for picking.  Then the objects  *  are drawn. */#define BUFSIZE 512void pickRects(int button, int state, int x, int y){   GLuint selectBuf[BUFSIZE];   GLint hits;   GLint viewport[4];   if (button != GLUT_LEFT_BUTTON || state != GLUT_DOWN)      return;   glGetIntegerv(GL_VIEWPORT, viewport);   glSelectBuffer(BUFSIZE, selectBuf);   (void) glRenderMode(GL_SELECT);   glInitNames();   glPushName(0);   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);   glOrtho(0.0, 8.0, 0.0, 8.0, -0.5, 2.5);   drawRects(GL_SELECT);   glPopMatrix();   glFlush();   hits = glRenderMode(GL_RENDER);   processHits(hits, selectBuf);}void display(void){   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);   drawRects(GL_RENDER);   glFlush();}void reshape(int w, int h){   glViewport(0, 0, (GLsizei) w, (GLsizei) h);   glMatrixMode(GL_PROJECTION);   glLoadIdentity();   glOrtho(0.0, 8.0, 0.0, 8.0, -0.5, 2.5);   glMatrixMode(GL_MODELVIEW);   glLoadIdentity();}void keyboard(unsigned char key, int x, int y){   switch (key) {      case 27:         exit(0);         break;   }}/*  Main Loop */int main(int argc, char **argv){   glutInit(&argc, argv);   glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);   glutInitWindowSize (200, 200);   glutInitWindowPosition (100, 100);   glutCreateWindow(argv[0]);   init();   glutReshapeFunc(reshape);   glutDisplayFunc(display);   glutMouseFunc(pickRects);   glutKeyboardFunc(keyboard);   glutMainLoop();   return 0; }