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/*
* GL_EXT_texture_lod_bias demo
*
* Thanks to Michael Vance for implementing this extension in Mesa.
*
* Brian Paul
* 20 March 2000
*
* Copyright (C) 2000 Brian Paul All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <GL/glut.h>
#include <GL/glext.h>
#include "readtex.c" /* I know, this is a hack. */
#define TEXTURE_FILE "../images/girl.rgb"
static GLfloat Xrot = 0, Yrot = -30, Zrot = 0;
static GLboolean Anim = GL_TRUE;
static GLint Bias = 0, BiasStepSign = +1; /* ints avoid fp precision problem */
static GLint BiasMin = -400, BiasMax = 400;
static void
PrintString(const char *s)
{
while (*s) {
glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
s++;
}
}
static void Idle( void )
{
static int lastTime = 0;
int time = glutGet(GLUT_ELAPSED_TIME);
int step;
if (lastTime == 0)
lastTime = time;
else if (time - lastTime < 10)
return;
step = (time - lastTime) / 10 * BiasStepSign;
lastTime = time;
Bias += step;
if (Bias < BiasMin) {
Bias = BiasMin;
BiasStepSign = +1;
}
else if (Bias > BiasMax) {
Bias = BiasMax;
BiasStepSign = -1;
}
glutPostRedisplay();
}
static void Display( void )
{
char str[100];
glClear( GL_COLOR_BUFFER_BIT );
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
glOrtho(-1, 1, -1, 1, -1, 1);
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
glDisable(GL_TEXTURE_2D);
glColor3f(1,1,1);
glRasterPos3f(-0.9, -0.9, 0.0);
sprintf(str, "Texture LOD Bias = %4.1f", Bias * 0.01);
PrintString(str);
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
glTranslatef( 0.0, 0.0, -8.0 );
glPushMatrix();
glRotatef(Xrot, 1, 0, 0);
glRotatef(Yrot, 0, 1, 0);
glRotatef(Zrot, 0, 0, 1);
glEnable(GL_TEXTURE_2D);
glTexEnvf(GL_TEXTURE_FILTER_CONTROL_EXT, GL_TEXTURE_LOD_BIAS_EXT, 0.01 * Bias);
glBegin(GL_POLYGON);
glTexCoord2f(0, 0); glVertex2f(-1, -1);
glTexCoord2f(2, 0); glVertex2f( 1, -1);
glTexCoord2f(2, 2); glVertex2f( 1, 1);
glTexCoord2f(0, 2); glVertex2f(-1, 1);
glEnd();
glPopMatrix();
glutSwapBuffers();
}
static void Reshape( int width, int height )
{
glViewport( 0, 0, width, height );
}
static void Key( unsigned char key, int x, int y )
{
const GLfloat step = 3.0;
(void) x;
(void) y;
switch (key) {
case 'a':
Anim = !Anim;
if (Anim)
glutIdleFunc(Idle);
else
glutIdleFunc(NULL);
break;
case 'z':
Zrot -= step;
break;
case 'Z':
Zrot += step;
break;
case 'b':
Bias -= 10;
break;
case 'B':
Bias += 10;
break;
case 27:
exit(0);
break;
}
glutPostRedisplay();
}
static void SpecialKey( int key, int x, int y )
{
const GLfloat step = 3.0;
(void) x;
(void) y;
switch (key) {
case GLUT_KEY_UP:
Xrot -= step;
break;
case GLUT_KEY_DOWN:
Xrot += step;
break;
case GLUT_KEY_LEFT:
Yrot -= step;
break;
case GLUT_KEY_RIGHT:
Yrot += step;
break;
}
glutPostRedisplay();
}
static void Init( void )
{
const char *exten = (const char *) glGetString(GL_EXTENSIONS);
GLfloat maxBias;
if (!strstr(exten, "GL_EXT_texture_lod_bias")) {
printf("Sorry, GL_EXT_texture_lod_bias not supported by this renderer.\n");
exit(1);
}
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
if (!LoadRGBMipmaps(TEXTURE_FILE, GL_RGB)) {
printf("Error: could not load texture image %s\n", TEXTURE_FILE);
exit(1);
}
/* mipmapping required for this extension */
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glGetFloatv(GL_MAX_TEXTURE_LOD_BIAS_EXT, &maxBias);
printf("LOD bias range: [%g, %g]\n", -maxBias, maxBias);
BiasMin = -100 * maxBias;
BiasMax = 100 * maxBias;
}
int main( int argc, char *argv[] )
{
glutInit( &argc, argv );
glutInitWindowPosition( 0, 0 );
glutInitWindowSize( 350, 350 );
glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
glutCreateWindow(argv[0]);
glutReshapeFunc( Reshape );
glutKeyboardFunc( Key );
glutSpecialFunc( SpecialKey );
glutDisplayFunc( Display );
if (Anim)
glutIdleFunc(Idle);
Init();
glutMainLoop();
return 0;
}
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