progs/redbook/bezcurve.c

   1 /*
   2  * Copyright (c) 1993-1997, Silicon Graphics, Inc.
   3  * ALL RIGHTS RESERVED
   4  * Permission to use, copy, modify, and distribute this software for
   5  * any purpose and without fee is hereby granted, provided that the above
   6  * copyright notice appear in all copies and that both the copyright notice
   7  * and this permission notice appear in supporting documentation, and that
   8  * the name of Silicon Graphics, Inc. not be used in advertising
   9  * or publicity pertaining to distribution of the software without specific,
  10  * written prior permission.
  11  *
  12  * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
  13  * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
  14  * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
  15  * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
  16  * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
  17  * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
  18  * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
  19  * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
  20  * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
  21  * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
  22  * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
  23  * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
  24  *
  25  * US Government Users Restricted Rights
  26  * Use, duplication, or disclosure by the Government is subject to
  27  * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
  28  * (c)(1)(ii) of the Rights in Technical Data and Computer Software
  29  * clause at DFARS 252.227-7013 and/or in similar or successor
  30  * clauses in the FAR or the DOD or NASA FAR Supplement.
  31  * Unpublished-- rights reserved under the copyright laws of the
  32  * United States.  Contractor/manufacturer is Silicon Graphics,
  33  * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
  34  *
  35  * OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
  36  */
  37
  38 /*  bezcurve.c
  39  *  This program uses evaluators to draw a Bezier curve.
  40  */
  41 #include <stdlib.h>
  42 #include <GL/glut.h>
  43
  44 GLfloat ctrlpoints[4][3] = {
  45         { -4.0, -4.0, 0.0}, { -2.0, 4.0, 0.0},
  46         {2.0, -4.0, 0.0}, {4.0, 4.0, 0.0}};
  47
  48 static void init(void)
  49 {
  50    glClearColor(0.0, 0.0, 0.0, 0.0);
  51    glShadeModel(GL_FLAT);
  52    glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 4, &ctrlpoints[0][0]);
  53    glEnable(GL_MAP1_VERTEX_3);
  54 }
  55
  56 static void display(void)
  57 {
  58    int i;
  59
  60    glClear(GL_COLOR_BUFFER_BIT);
  61    glColor3f(1.0, 1.0, 1.0);
  62    glBegin(GL_LINE_STRIP);
  63       for (i = 0; i <= 30; i++)
  64          glEvalCoord1f((GLfloat) i/30.0);
  65    glEnd();
  66    /* The following code displays the control points as dots. */
  67    glPointSize(5.0);
  68    glColor3f(1.0, 1.0, 0.0);
  69    glBegin(GL_POINTS);
  70       for (i = 0; i < 4; i++)
  71          glVertex3fv(&ctrlpoints[i][0]);
  72    glEnd();
  73    glFlush();
  74 }
  75
  76 static void reshape(int w, int h)
  77 {
  78    glViewport(0, 0, (GLsizei) w, (GLsizei) h);
  79    glMatrixMode(GL_PROJECTION);
  80    glLoadIdentity();
  81    if (w <= h)
  82       glOrtho(-5.0, 5.0, -5.0*(GLfloat)h/(GLfloat)w,
  83                5.0*(GLfloat)h/(GLfloat)w, -5.0, 5.0);
  84    else
  85       glOrtho(-5.0*(GLfloat)w/(GLfloat)h,
  86                5.0*(GLfloat)w/(GLfloat)h, -5.0, 5.0, -5.0, 5.0);
  87    glMatrixMode(GL_MODELVIEW);
  88    glLoadIdentity();
  89 }
  90
  91 /* ARGSUSED1 */
  92 static void keyboard(unsigned char key, int x, int y)
  93 {
  94    switch (key) {
  95       case 27:
  96          exit(0);
  97          break;
  98    }
  99 }
 100
 101 int main(int argc, char** argv)
 102 {
 103    glutInit(&argc, argv);
 104    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
 105    glutInitWindowSize (500, 500);
 106    glutInitWindowPosition (100, 100);
 107    glutCreateWindow (argv[0]);
 108    init ();
 109    glutDisplayFunc(display);
 110    glutReshapeFunc(reshape);
 111    glutKeyboardFunc (keyboard);
 112    glutMainLoop();
 113    return 0;
 114 }