progs/demos/spectex.c

   1 /* $Id: spectex.c,v 1.1 1999/08/19 00:55:40 jtg Exp $ */
   2
   3 /*
   4  * GLUT demonstration of texturing with specular highlights.
   5  *
   6  * When drawing a lit, textured surface one usually wants the specular
   7  * highlight to override the texture colors.  However, OpenGL applies
   8  * texturing after lighting so the specular highlight is modulated by
   9  * the texture.
  10  *
  11  * The solution here shown here is a two-pass algorithm:
  12  *  1. Draw the textured surface without specular lighting.
  13  *  2. Enable blending to add the next pass:
  14  *  3. Redraw the surface with a matte white material and only the
  15  *     specular components of light sources enabled.
  16  *
  17  * Brian Paul  February 1997
  18  */
  19
  20
  21 /*
  22  * $Log: spectex.c,v $
  23  * Revision 1.1  1999/08/19 00:55:40  jtg
  24  * Initial revision
  25  *
  26  * Revision 3.2  1999/03/28 18:22:05  brianp
  27  * minor clean-up
  28  *
  29  * Revision 3.1  1998/02/14 18:47:48  brianp
  30  * added OpenGL 1.2 separate specular interpolation support
  31  *
  32  * Revision 3.0  1998/02/14 18:42:29  brianp
  33  * initial rev
  34  *
  35  */
  36
  37
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include <math.h>
  41 #include <GL/glut.h>
  42
  43
  44 static GLUquadricObj *Quadric;
  45 static GLuint Sphere;
  46 static GLfloat LightPos[4] = {10.0, 10.0, 10.0, 1.0};
  47 static GLfloat Delta = 1.0;
  48 static GLint Mode = 0;
  49
  50 /*static GLfloat Blue[4] = {0.0, 0.0, 1.0, 1.0};*/
  51 /*static GLfloat Gray[4] = {0.5, 0.5, 0.5, 1.0};*/
  52 static GLfloat Black[4] = {0.0, 0.0, 0.0, 1.0};
  53 static GLfloat White[4] = {1.0, 1.0, 1.0, 1.0};
  54
  55
  56
  57 static void Idle( void )
  58 {
  59    LightPos[0] += Delta;
  60    if (LightPos[0]>15.0)
  61       Delta = -1.0;
  62    else if (LightPos[0]<-15.0)
  63       Delta = 1.0;
  64
  65    glutPostRedisplay();
  66 }
  67
  68
  69 static void Display( void )
  70 {
  71    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
  72
  73    glLightfv(GL_LIGHT0, GL_POSITION, LightPos);
  74
  75    glPushMatrix();
  76    glRotatef(90.0, 1.0, 0.0, 0.0);
  77
  78    if (Mode==0) {
  79       /* Typical method: diffuse + specular + texture */
  80       glEnable(GL_TEXTURE_2D);
  81       glLightfv(GL_LIGHT0, GL_DIFFUSE, White);  /* enable diffuse */
  82       glLightfv(GL_LIGHT0, GL_SPECULAR, White);  /* enable specular */
  83 #ifdef GL_VERSION_1_2
  84       glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL, GL_SINGLE_COLOR);
  85 #endif
  86       glCallList(Sphere);
  87    }
  88    else if (Mode==1) {
  89       /* just specular highlight */
  90       glDisable(GL_TEXTURE_2D);
  91       glLightfv(GL_LIGHT0, GL_DIFFUSE, Black);  /* disable diffuse */
  92       glLightfv(GL_LIGHT0, GL_SPECULAR, White);  /* enable specular */
  93 #ifdef GL_VERSION_1_2
  94       glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL, GL_SINGLE_COLOR);
  95 #endif
  96       glCallList(Sphere);
  97    }
  98    else if (Mode==2) {
  99       /* diffuse textured */
 100       glEnable(GL_TEXTURE_2D);
 101       glLightfv(GL_LIGHT0, GL_DIFFUSE, White);  /* enable diffuse */
 102       glLightfv(GL_LIGHT0, GL_SPECULAR, Black);  /* disable specular */
 103 #ifdef GL_VERSION_1_2
 104       glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL, GL_SINGLE_COLOR);
 105 #endif
 106       glCallList(Sphere);
 107    }
 108    else if (Mode==3) {
 109       /* 2-pass: diffuse textured then add specular highlight*/
 110       glEnable(GL_TEXTURE_2D);
 111       glLightfv(GL_LIGHT0, GL_DIFFUSE, White);  /* enable diffuse */
 112       glLightfv(GL_LIGHT0, GL_SPECULAR, Black);  /* disable specular */
 113 #ifdef GL_VERSION_1_2
 114       glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL, GL_SINGLE_COLOR);
 115 #endif
 116       glCallList(Sphere);
 117       /* specular highlight */
 118       glDepthFunc(GL_EQUAL);  /* redraw same pixels */
 119       glDisable(GL_TEXTURE_2D);
 120       glEnable(GL_BLEND);  /* add */
 121       glLightfv(GL_LIGHT0, GL_DIFFUSE, Black);  /* disable diffuse */
 122       glLightfv(GL_LIGHT0, GL_SPECULAR, White);  /* enable specular */
 123       glCallList(Sphere);
 124       glDepthFunc(GL_LESS);
 125       glDisable(GL_BLEND);
 126    }
 127    else if (Mode==4) {
 128       /* OpenGL 1.2's separate diffuse and specular color */
 129       glEnable(GL_TEXTURE_2D);
 130       glLightfv(GL_LIGHT0, GL_DIFFUSE, White);  /* enable diffuse */
 131       glLightfv(GL_LIGHT0, GL_SPECULAR, White);  /* enable specular */
 132 #ifdef GL_VERSION_1_2
 133       glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL, GL_SEPARATE_SPECULAR_COLOR);
 134 #endif
 135       glCallList(Sphere);
 136    }
 137
 138    glPopMatrix();
 139
 140    glutSwapBuffers();
 141 }
 142
 143
 144 static void Reshape( int width, int height )
 145 {
 146    glViewport( 0, 0, width, height );
 147    glMatrixMode( GL_PROJECTION );
 148    glLoadIdentity();
 149    glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
 150    glMatrixMode( GL_MODELVIEW );
 151    glLoadIdentity();
 152    glTranslatef( 0.0, 0.0, -12.0 );
 153 }
 154
 155
 156 static void Key( unsigned char key, int x, int y )
 157 {
 158    (void) x;
 159    (void) y;
 160    switch (key) {
 161       case 27:
 162          exit(0);
 163          break;
 164    }
 165    glutPostRedisplay();
 166 }
 167
 168
 169 static void SpecialKey( int key, int x, int y )
 170 {
 171    (void) x;
 172    (void) y;
 173    switch (key) {
 174       case GLUT_KEY_UP:
 175          break;
 176       case GLUT_KEY_DOWN:
 177          break;
 178    }
 179    glutPostRedisplay();
 180 }
 181
 182
 183 static void Init( void )
 184 {
 185    int i, j;
 186    GLubyte texImage[64][64][3];
 187
 188    glEnable(GL_LIGHTING);
 189    glEnable(GL_LIGHT0);
 190    glLightModeli(GL_LIGHT_MODEL_TWO_SIDE, 0);
 191    glLightModelfv(GL_LIGHT_MODEL_AMBIENT, Black);
 192
 193    glMaterialfv(GL_FRONT, GL_DIFFUSE, White);
 194    glMaterialfv(GL_FRONT, GL_SPECULAR, White);
 195    glMaterialf(GL_FRONT, GL_SHININESS, 20.0);
 196
 197    /* Actually, these are set again later */
 198    glLightfv(GL_LIGHT0, GL_DIFFUSE, White);
 199    glLightfv(GL_LIGHT0, GL_SPECULAR, White);
 200
 201    Quadric = gluNewQuadric();
 202    gluQuadricTexture( Quadric, GL_TRUE );
 203
 204    Sphere= glGenLists(1);
 205    glNewList( Sphere, GL_COMPILE );
 206    gluSphere( Quadric, 1.0, 24, 24 );
 207    glEndList();
 208
 209    glEnable(GL_DEPTH_TEST);
 210    glEnable(GL_CULL_FACE);
 211
 212    for (i=0;i<64;i++) {
 213       for (j=0;j<64;j++) {
 214          int k = ((i>>3)&1) ^ ((j>>3)&1);
 215          texImage[i][j][0] = 255*k;
 216          texImage[i][j][1] = 255*(1-k);
 217          texImage[i][j][2] = 0;
 218       }
 219    }
 220
 221    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 222    glTexImage2D( GL_TEXTURE_2D,
 223                  0,
 224                  3,
 225                  64, 64,
 226                  0,
 227                  GL_RGB, GL_UNSIGNED_BYTE,
 228                  texImage );
 229    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 230    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 231    glEnable(GL_TEXTURE_2D);
 232
 233    glBlendFunc(GL_ONE, GL_ONE);
 234 }
 235
 236
 237 static void ModeMenu(int entry)
 238 {
 239    if (entry==99)
 240       exit(0);
 241    Mode = entry;
 242 }
 243
 244
 245 int main( int argc, char *argv[] )
 246 {
 247
 248    glutInit( &argc, argv );
 249    glutInitWindowPosition( 0, 0 );
 250    glutInitWindowSize( 300, 300 );
 251
 252    glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
 253
 254    glutCreateWindow( "spectex" );
 255
 256    Init();
 257
 258    glutReshapeFunc( Reshape );
 259    glutKeyboardFunc( Key );
 260    glutSpecialFunc( SpecialKey );
 261    glutDisplayFunc( Display );
 262    glutIdleFunc( Idle );
 263
 264    glutCreateMenu( ModeMenu );
 265    glutAddMenuEntry("1-pass lighting + texturing", 0);
 266    glutAddMenuEntry("specular lighting", 1);
 267    glutAddMenuEntry("diffuse lighting + texturing", 2);
 268    glutAddMenuEntry("2-pass lighting + texturing", 3);
 269 #ifdef GL_VERSION_1_2
 270    glutAddMenuEntry("OpenGL 1.2 separate specular", 4);
 271 #endif
 272    glutAddMenuEntry("Quit", 99);
 273    glutAttachMenu(GLUT_RIGHT_BUTTON);
 274
 275    glutMainLoop();
 276    return 0;
 277 }