progs/redbook/pointp.c

   1 /*
   2  * Copyright (c) 1993-2003, Silicon Graphics, Inc.
   3  * All Rights Reserved
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose and without fee is hereby granted, provided that the above
   7  * copyright notice appear in all copies and that both the copyright
   8  * notice and this permission notice appear in supporting documentation,
   9  * and that the name of Silicon Graphics, Inc. not be used in
  10  * advertising or publicity pertaining to distribution of the software
  11  * without specific, written prior permission.
  12  *
  13  * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS" AND
  14  * WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
  16  * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
  17  * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
  18  * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
  19  * OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION, LOSS OF
  20  * PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF THIRD
  21  * PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN ADVISED OF
  22  * THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON ANY THEORY OF
  23  * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE POSSESSION, USE
  24  * OR PERFORMANCE OF THIS SOFTWARE.
  25  *
  26  * US Government Users Restricted Rights
  27  * Use, duplication, or disclosure by the Government is subject to
  28  * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
  29  * (c)(1)(ii) of the Rights in Technical Data and Computer Software
  30  * clause at DFARS 252.227-7013 and/or in similar or successor clauses
  31  * in the FAR or the DOD or NASA FAR Supplement.  Unpublished - rights
  32  * reserved under the copyright laws of the United States.
  33  *
  34  * Contractor/manufacturer is:
  35  *      Silicon Graphics, Inc.
  36  *      1500 Crittenden Lane
  37  *      Mountain View, CA  94043
  38  *      United State of America
  39  *
  40  * OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
  41  */
  42
  43 /*
  44  *  pointp.c
  45  *  This program demonstrates point parameters and their effect
  46  *  on point primitives.
  47  *  250 points are randomly generated within a 10 by 10 by 40
  48  *  region, centered at the origin.  In some modes (including the
  49  *  default), points that are closer to the viewer will appear larger.
  50  *
  51  *  Pressing the 'l', 'q', and 'c' keys switch the point
  52  *  parameters attenuation mode to linear, quadratic, or constant,
  53  *  respectively.
  54  *  Pressing the 'f' and 'b' keys move the viewer forward
  55  *  and backwards.  In either linear or quadratic attenuation
  56  *  mode, the distance from the viewer to the point will change
  57  *  the size of the point primitive.
  58  *  Pressing the '+' and '-' keys will change the current point
  59  *  size.  In this program, the point size is bounded, so it
  60  *  will not get less than 2.0, nor greater than GL_POINT_SIZE_MAX.
  61  */
  62
  63 #define GL_GLEXT_PROTOTYPES
  64
  65 #include <GL/glut.h>
  66 #include <stdlib.h>
  67 #include <stdio.h>
  68
  69 static GLfloat psize = 7.0;
  70 static GLfloat pmax[1];
  71 static GLfloat constant[3] = {1.0, 0.0, 0.0};
  72 static GLfloat linear[3] = {0.0, 0.12, 0.0};
  73 static GLfloat quadratic[3] = {0.0, 0.0, 0.01};
  74
  75 static void init(void)
  76 {
  77    int i;
  78
  79    srand (12345);
  80
  81    glNewList(1, GL_COMPILE);
  82    glBegin (GL_POINTS);
  83       for (i = 0; i < 250; i++) {
  84           glColor3f (1.0, ((rand()/(float) RAND_MAX) * 0.5) + 0.5,
  85                           rand()/(float) RAND_MAX);
  86 /*  randomly generated vertices:
  87     -5 < x < 5;  -5 < y < 5;  -5 < z < -45  */
  88           glVertex3f ( ((rand()/(float)RAND_MAX) * 10.0) - 5.0,
  89                        ((rand()/(float)RAND_MAX) * 10.0) - 5.0,
  90                        ((rand()/(float)RAND_MAX) * 40.0) - 45.0);
  91       }
  92    glEnd();
  93    glEndList();
  94
  95    glEnable(GL_DEPTH_TEST);
  96    glEnable(GL_POINT_SMOOTH);
  97    glEnable(GL_BLEND);
  98    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  99    glPointSize(psize);
 100    glGetFloatv(GL_POINT_SIZE_MAX_EXT, pmax);
 101
 102    glPointParameterfvEXT (GL_DISTANCE_ATTENUATION_EXT, linear);
 103    glPointParameterfEXT (GL_POINT_FADE_THRESHOLD_SIZE_EXT, 2.0);
 104 }
 105
 106 static void display(void)
 107 {
 108    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 109    glCallList (1);
 110    glutSwapBuffers ();
 111 }
 112
 113 static void reshape (int w, int h)
 114 {
 115    glViewport (0, 0, (GLsizei) w, (GLsizei) h);
 116    glMatrixMode (GL_PROJECTION);
 117    glLoadIdentity ();
 118    gluPerspective (35.0, 1.0, 0.25, 200.0);
 119    glMatrixMode (GL_MODELVIEW);
 120    glTranslatef (0.0, 0.0, -10.0);
 121 }
 122
 123 static void keyboard(unsigned char key, int x, int y)
 124 {
 125    switch (key) {
 126       case 'b':
 127             glMatrixMode (GL_MODELVIEW);
 128             glTranslatef (0.0, 0.0, -0.5);
 129             glutPostRedisplay();
 130          break;
 131       case 'c':
 132             glPointParameterfvEXT (GL_DISTANCE_ATTENUATION_EXT, constant);
 133             glutPostRedisplay();
 134          break;
 135       case 'f':
 136             glMatrixMode (GL_MODELVIEW);
 137             glTranslatef (0.0, 0.0, 0.5);
 138             glutPostRedisplay();
 139          break;
 140       case 'l':
 141             glPointParameterfvEXT (GL_DISTANCE_ATTENUATION_EXT, linear);
 142             glutPostRedisplay();
 143          break;
 144       case 'q':
 145             glPointParameterfvEXT (GL_DISTANCE_ATTENUATION_EXT, quadratic);
 146             glutPostRedisplay();
 147          break;
 148       case '+':
 149             if (psize < (pmax[0] + 1.0))
 150                psize = psize + 1.0;
 151             glPointSize (psize);
 152             glutPostRedisplay();
 153          break;
 154       case '-':
 155             if (psize >= 2.0)
 156                psize = psize - 1.0;
 157             glPointSize (psize);
 158             glutPostRedisplay();
 159          break;
 160       case 27:
 161          exit(0);
 162          break;
 163    }
 164 }
 165
 166 int main(int argc, char** argv)
 167 {
 168    glutInit(&argc, argv);
 169    glutInitDisplayMode (GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH | GLUT_MULTISAMPLE);
 170    glutInitWindowSize (500, 500);
 171    glutInitWindowPosition (100, 100);
 172    glutCreateWindow (argv[0]);
 173    init ();
 174    glutDisplayFunc (display);
 175    glutReshapeFunc (reshape);
 176    glutKeyboardFunc (keyboard);
 177    glutMainLoop();
 178    return 0;
 179 }