src/redbook/texgen.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  31  * Unpublished-- rights reserved under the copyright laws of the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 /*  texgen.c
  39  *  This program draws a texture mapped teapot with
  40  *  automatically generated texture coordinates.  The
  41  *  texture is rendered as stripes on the teapot.
  42  *  Initially, the object is drawn with texture coordinates
  43  *  based upon the object coordinates of the vertex
  44  *  and distance from the plane x = 0.  Pressing the 'e'
  45  *  key changes the coordinate generation to eye coordinates
  46  *  of the vertex.  Pressing the 'o' key switches it back
  47  *  to the object coordinates.  Pressing the 's' key
  48  *  changes the plane to a slanted one (x + y + z = 0).
  49  *  Pressing the 'x' key switches it back to x = 0.
  50  */
  51
  52 #include "glut_wrap.h"
  53 #include <stdlib.h>
  54 #include <stdio.h>
  55
  56 #define stripeImageWidth 32
  57 GLubyte stripeImage[4*stripeImageWidth];
  58
  59 #ifdef GL_VERSION_1_1
  60 static GLuint texName;
  61 #endif
  62
  63 static void makeStripeImage(void)
  64 {
  65    int j;
  66
  67    for (j = 0; j < stripeImageWidth; j++) {
  68       stripeImage[4*j] = (GLubyte) ((j<=4) ? 255 : 0);
  69       stripeImage[4*j+1] = (GLubyte) ((j>4) ? 255 : 0);
  70       stripeImage[4*j+2] = (GLubyte) 0;
  71       stripeImage[4*j+3] = (GLubyte) 255;
  72    }
  73 }
  74
  75 /*  planes for texture coordinate generation  */
  76 static GLfloat xequalzero[] = {1.0, 0.0, 0.0, 0.0};
  77 static GLfloat slanted[] = {1.0, 1.0, 1.0, 0.0};
  78 static GLfloat *currentCoeff;
  79 static GLenum currentPlane;
  80 static GLint currentGenMode;
  81
  82 static void init(void)
  83 {
  84    glClearColor (0.0, 0.0, 0.0, 0.0);
  85    glEnable(GL_DEPTH_TEST);
  86    glShadeModel(GL_SMOOTH);
  87
  88    makeStripeImage();
  89    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  90
  91 #ifdef GL_VERSION_1_1
  92    glGenTextures(1, &texName);
  93    glBindTexture(GL_TEXTURE_1D, texName);
  94 #endif
  95    glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_REPEAT);
  96    glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  97    glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  98 #ifdef GL_VERSION_1_1
  99    glTexImage1D(GL_TEXTURE_1D, 0, GL_RGBA, stripeImageWidth, 0,
 100                 GL_RGBA, GL_UNSIGNED_BYTE, stripeImage);
 101 #else
 102    glTexImage1D(GL_TEXTURE_1D, 0, 4, stripeImageWidth, 0,
 103                 GL_RGBA, GL_UNSIGNED_BYTE, stripeImage);
 104 #endif
 105
 106    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 107    currentCoeff = xequalzero;
 108    currentGenMode = GL_OBJECT_LINEAR;
 109    currentPlane = GL_OBJECT_PLANE;
 110    glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, currentGenMode);
 111    glTexGenfv(GL_S, currentPlane, currentCoeff);
 112
 113    glEnable(GL_TEXTURE_GEN_S);
 114    glEnable(GL_TEXTURE_1D);
 115    glEnable(GL_CULL_FACE);
 116    glEnable(GL_LIGHTING);
 117    glEnable(GL_LIGHT0);
 118    glEnable(GL_AUTO_NORMAL);
 119    glEnable(GL_NORMALIZE);
 120    glFrontFace(GL_CW);
 121    glCullFace(GL_BACK);
 122    glMaterialf (GL_FRONT, GL_SHININESS, 64.0);
 123 }
 124
 125 static void display(void)
 126 {
 127    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 128
 129    glPushMatrix ();
 130    glRotatef(45.0, 0.0, 0.0, 1.0);
 131 #ifdef GL_VERSION_1_1
 132    glBindTexture(GL_TEXTURE_1D, texName);
 133 #endif
 134    glutSolidTeapot(2.0);
 135    glPopMatrix ();
 136    glFlush();
 137 }
 138
 139 static void reshape(int w, int h)
 140 {
 141    glViewport(0, 0, (GLsizei) w, (GLsizei) h);
 142    glMatrixMode(GL_PROJECTION);
 143    glLoadIdentity();
 144    if (w <= h)
 145       glOrtho (-3.5, 3.5, -3.5*(GLfloat)h/(GLfloat)w,
 146                3.5*(GLfloat)h/(GLfloat)w, -3.5, 3.5);
 147    else
 148       glOrtho (-3.5*(GLfloat)w/(GLfloat)h,
 149                3.5*(GLfloat)w/(GLfloat)h, -3.5, 3.5, -3.5, 3.5);
 150    glMatrixMode(GL_MODELVIEW);
 151    glLoadIdentity();
 152 }
 153
 154 /* ARGSUSED1 */
 155 static void keyboard (unsigned char key, int x, int y)
 156 {
 157    switch (key) {
 158       case 'e':
 159       case 'E':
 160          currentGenMode = GL_EYE_LINEAR;
 161          currentPlane = GL_EYE_PLANE;
 162          glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, currentGenMode);
 163          glTexGenfv(GL_S, currentPlane, currentCoeff);
 164          glutPostRedisplay();
 165          break;
 166       case 'o':
 167       case 'O':
 168          currentGenMode = GL_OBJECT_LINEAR;
 169          currentPlane = GL_OBJECT_PLANE;
 170          glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, currentGenMode);
 171          glTexGenfv(GL_S, currentPlane, currentCoeff);
 172          glutPostRedisplay();
 173          break;
 174       case 's':
 175       case 'S':
 176          currentCoeff = slanted;
 177          glTexGenfv(GL_S, currentPlane, currentCoeff);
 178          glutPostRedisplay();
 179          break;
 180       case 'x':
 181       case 'X':
 182          currentCoeff = xequalzero;
 183          glTexGenfv(GL_S, currentPlane, currentCoeff);
 184          glutPostRedisplay();
 185          break;
 186       case 27:
 187          exit(0);
 188          break;
 189       default:
 190          break;
 191    }
 192 }
 193
 194 int main(int argc, char** argv)
 195 {
 196    glutInit(&argc, argv);
 197    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
 198    glutInitWindowSize(256, 256);
 199    glutInitWindowPosition(100, 100);
 200    glutCreateWindow (argv[0]);
 201    init ();
 202    glutDisplayFunc(display);
 203    glutReshapeFunc(reshape);
 204    glutKeyboardFunc(keyboard);
 205    glutMainLoop();
 206    return 0;
 207 }