progs/demos/lodbias.c

   1 /*
   2  * GL_EXT_texture_lod_bias demo
   3  *
   4  * Thanks to Michael Vance for implementing this extension in Mesa.
   5  *
   6  * Brian Paul
   7  * 20 March 2000
   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
  30 #include <stdlib.h>
  31 #include <stdio.h>
  32 #include <math.h>
  33 #include <GL/glut.h>
  34 #include <GL/glext.h>
  35
  36 #include "../util/readtex.c"   /* I know, this is a hack. */
  37
  38 #define TEXTURE_FILE "../images/girl.rgb"
  39
  40 static GLfloat Xrot = 0, Yrot = -30, Zrot = 0;
  41 static GLboolean Anim = GL_TRUE;
  42 static GLint Bias = 0, BiasStepSign = +1; /* ints avoid fp precision problem */
  43 static GLint BiasMin = -200, BiasMax = 500;
  44
  45
  46
  47 static void
  48 PrintString(const char *s)
  49 {
  50    while (*s) {
  51       glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
  52       s++;
  53    }
  54 }
  55
  56 static void Idle( void )
  57 {
  58    static int lastTime = 0;
  59    int time = glutGet(GLUT_ELAPSED_TIME);
  60    int step;
  61
  62    if (lastTime == 0)
  63       lastTime = time;
  64    else if (time - lastTime < 10)
  65       return;
  66
  67    step = (time - lastTime) / 10 * BiasStepSign;
  68    lastTime = time;
  69
  70    Bias += step;
  71    if (Bias < BiasMin) {
  72       Bias = BiasMin;
  73       BiasStepSign = +1;
  74    }
  75    else if (Bias > BiasMax) {
  76       Bias = BiasMax;
  77       BiasStepSign = -1;
  78    }
  79
  80    glutPostRedisplay();
  81 }
  82
  83
  84 static void Display( void )
  85 {
  86    char str[100];
  87
  88    glClear( GL_COLOR_BUFFER_BIT );
  89
  90    glMatrixMode( GL_PROJECTION );
  91    glLoadIdentity();
  92    glOrtho(-1, 1, -1, 1, -1, 1);
  93    glMatrixMode( GL_MODELVIEW );
  94    glLoadIdentity();
  95
  96    glDisable(GL_TEXTURE_2D);
  97    glColor3f(1,1,1);
  98    glRasterPos3f(-0.9, -0.9, 0.0);
  99    sprintf(str, "Texture LOD Bias = %4.1f", Bias * 0.01);
 100    PrintString(str);
 101
 102    glMatrixMode( GL_PROJECTION );
 103    glLoadIdentity();
 104    glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
 105    glMatrixMode( GL_MODELVIEW );
 106    glLoadIdentity();
 107    glTranslatef( 0.0, 0.0, -8.0 );
 108
 109    glPushMatrix();
 110    glRotatef(Xrot, 1, 0, 0);
 111    glRotatef(Yrot, 0, 1, 0);
 112    glRotatef(Zrot, 0, 0, 1);
 113
 114    glEnable(GL_TEXTURE_2D);
 115    glTexEnvf(GL_TEXTURE_FILTER_CONTROL_EXT, GL_TEXTURE_LOD_BIAS_EXT, 0.01 * Bias);
 116
 117    glBegin(GL_POLYGON);
 118    glTexCoord2f(0, 0);  glVertex2f(-1, -1);
 119    glTexCoord2f(2, 0);  glVertex2f( 1, -1);
 120    glTexCoord2f(2, 2);  glVertex2f( 1,  1);
 121    glTexCoord2f(0, 2);  glVertex2f(-1,  1);
 122    glEnd();
 123
 124    glPopMatrix();
 125
 126    glutSwapBuffers();
 127 }
 128
 129
 130 static void Reshape( int width, int height )
 131 {
 132    glViewport( 0, 0, width, height );
 133 }
 134
 135
 136 static void Key( unsigned char key, int x, int y )
 137 {
 138    const GLfloat step = 3.0;
 139    (void) x;
 140    (void) y;
 141    switch (key) {
 142       case 'a':
 143          Anim = !Anim;
 144          if (Anim)
 145             glutIdleFunc(Idle);
 146          else
 147             glutIdleFunc(NULL);
 148          break;
 149       case 'z':
 150          Zrot -= step;
 151          break;
 152       case 'Z':
 153          Zrot += step;
 154          break;
 155       case 'b':
 156          Bias -= 10;
 157          break;
 158       case 'B':
 159          Bias += 10;
 160          break;
 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    const GLfloat step = 3.0;
 172    (void) x;
 173    (void) y;
 174    switch (key) {
 175       case GLUT_KEY_UP:
 176          Xrot -= step;
 177          break;
 178       case GLUT_KEY_DOWN:
 179          Xrot += step;
 180          break;
 181       case GLUT_KEY_LEFT:
 182          Yrot -= step;
 183          break;
 184       case GLUT_KEY_RIGHT:
 185          Yrot += step;
 186          break;
 187    }
 188    glutPostRedisplay();
 189 }
 190
 191
 192 static void Init( void )
 193 {
 194    const char *exten = (const char *) glGetString(GL_EXTENSIONS);
 195    if (!strstr(exten, "GL_EXT_texture_lod_bias")) {
 196       printf("Sorry, GL_EXT_texture_lod_bias not supported by this renderer.\n");
 197       exit(1);
 198    }
 199
 200    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 201    if (!LoadRGBMipmaps(TEXTURE_FILE, GL_RGB)) {
 202       printf("Error: could not load texture image %s\n", TEXTURE_FILE);
 203       exit(1);
 204    }
 205
 206    /* mipmapping required for this extension */
 207    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
 208    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 209    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 210 }
 211
 212
 213 int main( int argc, char *argv[] )
 214 {
 215    glutInit( &argc, argv );
 216    glutInitWindowPosition( 0, 0 );
 217    glutInitWindowSize( 350, 350 );
 218    glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
 219    glutCreateWindow(argv[0]);
 220    glutReshapeFunc( Reshape );
 221    glutKeyboardFunc( Key );
 222    glutSpecialFunc( SpecialKey );
 223    glutDisplayFunc( Display );
 224    if (Anim)
 225       glutIdleFunc(Idle);
 226    Init();
 227    glutMainLoop();
 228    return 0;
 229 }