Return to pickdepth.c CVS log

Up to [Development] / projects / ogl-sample / main / gfx / samples / redbook_2ed

Change license version to 1.1.

/*
 * License Applicability. Except to the extent portions of this file are
 * made subject to an alternative license as permitted in the SGI Free
 * Software License B, Version 1.1 (the "License"), the contents of this
 * file are subject only to the provisions of the License. You may not use
 * this file except in compliance with the License. You may obtain a copy
 * of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
 * Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
 * 
 * http://oss.sgi.com/projects/FreeB
 * 
 * Note that, as provided in the License, the Software is distributed on an
 * "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
 * DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
 * CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
 * PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
 * 
 * Original Code. The Original Code is: OpenGL Sample Implementation,
 * Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
 * Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
 * Copyright in any portions created by third parties is as indicated
 * elsewhere herein. All Rights Reserved.
 * 
 * Additional Notice Provisions: The application programming interfaces
 * established by SGI in conjunction with the Original Code are The
 * OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
 * April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
 * 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
 * Window System(R) (Version 1.3), released October 19, 1998. This software
 * was created using the OpenGL(R) version 1.2.1 Sample Implementation
 * published by SGI, but has not been independently verified as being
 * compliant with the OpenGL(R) version 1.2.1 Specification.
 *
 */

/*
 * 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 512

void 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; 
}