progs/demos/anisotropic.c

   1 /* $Id: anisotropic.c,v 1.1 2001/03/22 15:24:15 gareth Exp $ */
   2
   3 /*
   4  * GL_ARB_texture_filter_anisotropic demo
   5  *
   6  * Gareth Hughes
   7  * March 2001
   8  *
   9  * Copyright (C) 2000  Brian Paul   All Rights Reserved.
  10  *
  11  * Permission is hereby granted, free of charge, to any person obtaining a
  12  * copy of this software and associated documentation files (the "Software"),
  13  * to deal in the Software without restriction, including without limitation
  14  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  15  * and/or sell copies of the Software, and to permit persons to whom the
  16  * Software is furnished to do so, subject to the following conditions:
  17  *
  18  * The above copyright notice and this permission notice shall be included
  19  * in all copies or substantial portions of the Software.
  20  *
  21  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  22  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  24  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  25  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  26  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27  */
  28
  29 /* This is a fairly early version.  All it does is draw a couple of
  30  * textured quads with different forms of texture filtering.  Eventually,
  31  * you'll be able to adjust the maximum anisotropy and so on.
  32  */
  33
  34 #include <math.h>
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <GL/glut.h>
  38
  39 #define TEXTURE_SIZE 256
  40 static GLubyte image[TEXTURE_SIZE][TEXTURE_SIZE][3];
  41
  42 static GLfloat repeat = 1.0;
  43
  44 static GLfloat texcoords[] = {
  45    0.0, 0.0,
  46    0.0, 1.0,
  47    1.0, 0.0,
  48    1.0, 1.0
  49 };
  50
  51 static GLfloat vertices[] = {
  52    -400.0, -400.0,     0.0,
  53    -400.0,  400.0, -7000.0,
  54     400.0, -400.0,     0.0,
  55     400.0,  400.0, -7000.0
  56 };
  57
  58 static GLfloat maxAnisotropy;
  59
  60
  61 static void init( void )
  62 {
  63    int i, j;
  64
  65    if ( !glutExtensionSupported( "GL_EXT_texture_filter_anisotropic" ) ) {
  66       fprintf( stderr, "Sorry, this demo requires GL_EXT_texture_filter_anisotropic.\n" );
  67       exit( 0 );
  68    }
  69
  70    glClearColor( 0.0, 0.0, 0.0, 0.0 );
  71    glShadeModel( GL_SMOOTH );
  72
  73    /* Init the vertex arrays.
  74     */
  75    glEnableClientState( GL_VERTEX_ARRAY );
  76    glEnableClientState( GL_TEXTURE_COORD_ARRAY );
  77
  78    glVertexPointer( 3, GL_FLOAT, 0, vertices );
  79    glTexCoordPointer( 2, GL_FLOAT, 0, texcoords );
  80
  81    /* Init the texture environment.
  82     */
  83    glEnable( GL_TEXTURE_2D );
  84    glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE );
  85
  86    glMatrixMode( GL_TEXTURE );
  87    glScalef( repeat, repeat, 0 );
  88
  89    glMatrixMode( GL_MODELVIEW );
  90
  91    glGetFloatv( GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &maxAnisotropy );
  92    printf( "Maximum supported anisotropy: %.2f\n", maxAnisotropy );
  93
  94    /* Make the texture image.
  95     */
  96    glPixelStorei( GL_UNPACK_ALIGNMENT, 1 );
  97
  98    for ( i = 0 ; i < TEXTURE_SIZE ; i++ ) {
  99       for ( j = 0 ; j < TEXTURE_SIZE ; j++ ) {
 100          if ( (i/4 + j/4) & 1 ) {
 101             image[i][j][0] = 0;
 102             image[i][j][1] = 0;
 103             image[i][j][2] = 0;
 104          } else {
 105             image[i][j][0] = 255;
 106             image[i][j][1] = 255;
 107             image[i][j][2] = 255;
 108          }
 109       }
 110    }
 111
 112    gluBuild2DMipmaps( GL_TEXTURE_2D, GL_RGB, TEXTURE_SIZE, TEXTURE_SIZE,
 113                       GL_RGB, GL_UNSIGNED_BYTE, image );
 114 }
 115
 116 static void display( void )
 117 {
 118    GLint vp[4], w, h;
 119
 120    glClear( GL_COLOR_BUFFER_BIT );
 121
 122    glGetIntegerv( GL_VIEWPORT, vp );
 123    w = vp[2] / 2;
 124    h = vp[3] / 2;
 125
 126    /* Upper left corner:
 127     */
 128    glViewport( 1, h + 1, w - 2, h - 2 );
 129
 130    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 131    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, maxAnisotropy );
 132
 133    glDrawArrays( GL_TRIANGLE_STRIP, 0, 4 );
 134
 135
 136    /* Upper right corner:
 137     */
 138    glViewport( w + 1, h + 1, w - 2, h - 2 );
 139
 140    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST );
 141    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, maxAnisotropy );
 142
 143    glDrawArrays( GL_TRIANGLE_STRIP, 0, 4 );
 144
 145
 146    /* Lower left corner:
 147     */
 148    glViewport( 1, 1, w - 2, h - 2 );
 149
 150    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_LINEAR );
 151    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, maxAnisotropy );
 152
 153    glDrawArrays( GL_TRIANGLE_STRIP, 0, 4 );
 154
 155
 156    /* Lower right corner:
 157     */
 158    glViewport( w + 1, 1, w - 2, h - 2 );
 159
 160    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR );
 161    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, maxAnisotropy );
 162
 163    glDrawArrays( GL_TRIANGLE_STRIP, 0, 4 );
 164
 165
 166    glViewport( vp[0], vp[1], vp[2], vp[3] );
 167
 168    glutSwapBuffers();
 169 }
 170
 171 static void reshape( int w, int h )
 172 {
 173    glViewport( 0, 0, (GLsizei) w, (GLsizei) h );
 174
 175    glMatrixMode( GL_PROJECTION );
 176    glLoadIdentity();
 177    glFrustum( -1.0, 1.0, -1.0, 1.0, 10.0, 10000.0 );
 178
 179    glMatrixMode( GL_MODELVIEW );
 180    glLoadIdentity();
 181    glTranslatef( 0.0, 0.0, -10.0 );
 182 }
 183
 184 static void key( unsigned char key, int x, int y )
 185 {
 186    (void) x; (void) y;
 187
 188    switch ( key ) {
 189    case 27:
 190       exit( 0 );
 191    }
 192
 193    glutPostRedisplay();
 194 }
 195
 196 static void usage( void )
 197 {
 198    /* Nothing yet... */
 199 }
 200
 201 int main( int argc, char **argv )
 202 {
 203    glutInit( &argc, argv );
 204    glutInitDisplayMode( GLUT_DOUBLE | GLUT_RGB );
 205    glutInitWindowSize( 600, 300 );
 206    glutInitWindowPosition( 0, 0 );
 207    glutCreateWindow( "Anisotropic Texture Filter Demo" );
 208
 209    init();
 210
 211    glutDisplayFunc( display );
 212    glutReshapeFunc( reshape );
 213    glutKeyboardFunc( key );
 214
 215    usage();
 216
 217    glutMainLoop();
 218
 219    return 0;
 220 }