Opengl纹理压缩问题

[whucv]

程序下载http://download.csdn.net/detail/whucv/4187491

VC6.0下 256*256图片纹理， glGetCompressedTexImageARB(GL_TEXTURE_2D, 0, img);错误，求解决方案？程序在附件中。
求教纹理压缩的问题
glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_COMPRESSED_ARB, &compressed);
返回1，
可为什么调用
glGetCompressedTexImageARB(GL_TEXTURE_2D, 0, img);
错误呢？

// Texturetest.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include "gl/glew.h"
#include "gl/glaux.h"
#include "gl/glut.h"
#include "stdio.h"

GLuint  decal_map = 0;
GLuint  compressed_decal_map = 1;
GLuint  already_compressed_decal_map = 2;

AUX_RGBImageRec *LoadBMP(char* Filename)

{
    
    FILE *File=NULL;
    if (!Filename)    
    {    
        return NULL;        
    }    
    File=fopen(Filename,"r");    
    if (File)        
    {    
        return auxDIBImageLoad(Filename);        
    }    
    return NULL;    
}

void loadTextureAndCompress(void)
{
    int status=FALSE;
    AUX_RGBImageRec * image;
    memset(&decal_map,0,sizeof(void*)*1);
    
    int compressed;
    int internalformat;
    int compressed_size;
    int num_compressed_format;
    int * compressed_format = NULL;
    unsigned char * img = NULL;
    
    /* Assume tightly packed textures. */
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

  /* 原始纹理 original*/
    glBindTexture(GL_TEXTURE_2D, decal_map);
    image = LoadBMP("world.bmp"); /* "world.bmp" */
    gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB,image->sizeX, image->sizeY,GL_RGB, GL_UNSIGNED_BYTE, image->data);

    /* GL压缩图像到指定压缩格式 */
    glBindTexture(GL_TEXTURE_2D, compressed_decal_map);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_COMPRESSED_RGB_ARB, //压缩
        image->sizeX, image->sizeY,0,GL_BGR_EXT, GL_UNSIGNED_BYTE, image->data);
        
    /* 检查图像是否被GL成功压缩GL_TEXTURE_COMPRESSED_ARB*/
    glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_COMPRESSED_ARB, &compressed);
    /*if the compression has been successful 如果成功压缩*/
    if (compressed==GL_TRUE)
    {    
        /* 查询压缩图像的内部格式 */
        glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_INTERNAL_FORMAT, &internalformat);

        /* 查询压缩数据纹理缓冲区大小 */
        glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_COMPRESSED_IMAGE_SIZE_ARB, &compressed_size);

        //保存压缩文理的相关信息
        glGetIntegerv(GL_NUM_COMPRESSED_TEXTURE_FORMATS_ARB, &num_compressed_format);
        compressed_format = (GLint*)malloc(num_compressed_format * sizeof(GLint));
        glGetIntegerv(GL_COMPRESSED_TEXTURE_FORMATS_ARB, compressed_format);

        img = (unsigned char *)malloc(compressed_size * sizeof(unsigned char));
        /* 得到压缩纹理数据 */
        glGetCompressedTexImageARB(GL_TEXTURE_2D, 0, img);
         glBindTexture(GL_TEXTURE_2D, already_compressed_decal_map);
         glCompressedTexImage2DARB(GL_TEXTURE_2D, 0, internalformat, image->sizeX, image->sizeY, 0, compressed_size, img);
         
    }


    free(image->data);
    free(image);
    free(compressed_format);
    free(img);
}


void myDisplay()

{
    
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
    
    //LoadGLTexture();
    loadTextureAndCompress();
    
    glEnable(GL_TEXTURE_2D);
    
//    glBindTexture(GL_TEXTURE_2D,Texture[0]);
//    glBindTexture(GL_TEXTURE_2D,decal_map);
    glBindTexture(GL_TEXTURE_2D,already_compressed_decal_map);
    glBegin(GL_QUADS);
    
    GLUquadric* quadricObj=gluNewQuadric();
    
    gluQuadricTexture(quadricObj,GL_TRUE);
    gluSphere(quadricObj,1,50,50);
    gluDeleteQuadric(quadricObj);    
    glEnd();    
    glutSwapBuffers();
    
}


int main(int argc, char* argv[])
{
    glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB);
    
    glutCreateWindow("Boy");
    
    glutDisplayFunc(myDisplay);
    
    glutMainLoop();
    

    return 0;
}

[the_venus]

为什么没有调用glGenTextures()产生纹理对象呢？

[whucv]

[Quote=引用 2 楼 的回复:]
glTexImage2D(GL_TEXTURE_2D, 0, GL_COMPRESSED_RGB_ARB, //压缩
image->sizeX, image->sizeY,0,GL_BGR_EXT, GL_UNSIGNED_BYTE, image->data);
把GL_BGR_EXTN改为GL_RGB之后，glTexImage2D()才能调用成功。你可以再试试。。。
[/Quote]
我试了但是显示0指令引用0内存，还有其他需要修改的地方吗？the_venus能否给个可以运行的代码程序。

[the_venus]

glTexImage2D(GL_TEXTURE_2D, 0, GL_COMPRESSED_RGB_ARB, //压缩
image->sizeX, image->sizeY,0,GL_BGR_EXT, GL_UNSIGNED_BYTE, image->data);
把GL_BGR_EXTN改为GL_RGB之后，glTexImage2D()才能调用成功。你可以再试试。。。

[the_venus]

知道你的错误在哪儿吗？
你为什么不对glew库进行初始化？

在glutCreateWindow()后面加上
GLenum error;
error=glewInit();
if(error!=GLEW_OK)
{
printf(“GLEW 初始化失败.\n”);
return -1;
}

程序就没有问题了
还有，请在使用纹理之前调用glGenTextures()产生它，并在不用的时候调用glDeleteTextures()删除掉它。。。。。。

恶习。。。。

[bigmantouwangzi]

还是不能用呀，