启用
   if (gltIsExtSupported("GL_EXT_texture_filter_anisotropic"))
   {
    GLfloat fLargest;
    glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT,&fLargest);
    glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MAX_ANISOTROPY_EXT,fLargest);
   }

恢复

glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MAX_ANISOTROPY_EXT,1.0f);