c++ - glGenTextures works but returns the same texture name every single time -

i have class called texture. class responsible managing texture. in programs startup opengl context initialised (which makes question different involving unexpected glgentextures behaviour). texture gets texture name glgentextures() , loads , binds image data memory texture name int function texglinit(). works, , texture displayed expected.

however, want texture able change texture displays when user clicks button , selects 1 hdd in openfilediaglog. function called reloadtexture(). function attempts delete old image/pixel data memory , replace new data file selected user. when happens, deletes texture name using gldeletetextures, , assigns new texture name , loads new pixel data memory using function texglinit(). texture name same 1 before (usually '1') 100% of time.

the image displayed after happens odd. has new images dimensions, still old images pixels. put simply, distorts old image down new images size. it's still drawing using supposedly deleted pixel data. should happen screen displays new image file on screen. believe texture name not being unique.

the code included below:

texture::texture(string filename)//---constructor loads in initial image. works fine! {     textureid[0]=0;      const char* fnptr = filename.c_str(); //our image loader accepts ptr char, not string     //printf(fnptr);      lodepng::load_file(buffer, fnptr);//load file buffer      unsigned error = lodepng::decode(image,w,h,buffer);//lodepng's decode function load pixel data image vector buffer     //display errors texture     if(error)     {         cout << "\ndecoder error " << error << ": " << lodepng_error_text(error) <<endl;     }     //execute code that'll throw exceptions images size     checkpot(w);     checkpot(h);       //image contains our pixeldata. ready opengl thing      //let's texture in video memory     texglinit();      draw_from_corner = center;   }  void texture::reloadtexture(string filename)//reload texture replaces texture name , image/pixel data bound texture {     //first , foremost clear image , buffer vectors down nothing can start afresh      buffer.clear();     image.clear();     w = 0;     h = 0;     //also delete texture name using before     gldeletetextures(1, &textureid[0]);         const char* fnptr = filename.c_str(); //our image loader accepts ptr char, not string     //printf(fnptr);      lodepng::load_file(buffer, fnptr);//load file buffer      unsigned error = lodepng::decode(image,w,h,buffer);//lodepng's decode function load pixel data image vector buffer     //display errors texture     if(error)     {         cout << "\ndecoder error " << error << ": " << lodepng_error_text(error) <<endl;     }     //execute code that'll throw exceptions images size     checkpot(w);     checkpot(h);      //image contains our pixeldata. ready  thing      //let's texture in video memoryopengl     texglinit();      draw_from_corner = center; }  void texture::texglinit()//actually gets new texture name loads pixeldata opengl {     glgentextures(1, &textureid[0]);     ////printf("\ntextureid = %u", textureid[0]);     glbindtexture(gl_texture_2d, textureid[0]);//evrything we're about texture     glpixelstorei(gl_unpack_alignment, 1);     gltexparameteri (gl_texture_2d, gl_texture_min_filter, gl_nearest);     gltexenvf(gl_texture_env, gl_texture_env_mode, gl_modulate);     //gldisable(gl_color_material);     glteximage2d(gl_texture_2d, 0, gl_rgba8,w,h,0, gl_rgba, gl_unsigned_byte, &image[0]);     //we free image vectors memory right now. we'll when there's need to. @ beginning of reloadtexture func, makes sure happens when need to.    } 

for it's worth here draw function in texture class.

void texture::draw(point* origin, anchor drawfrom) {     //let set dfc enum here.     draw_from_corner = drawfrom;      glenable(gl_texture_2d);     //printf("\ndrawing texture @ (%f, %f)",centerpoint.x, centerpoint.y);     glbindtexture(gl_texture_2d, textureid[0]);//bind texture     //create quick vertex array primitive we're going bind texture     ////printf("texid = %u",textureid[0]);     glfloat varray[8];  #pragma region anchor switch     switch (draw_from_corner)     {     case center:          varray[0] = origin->x-(w/2); varray[1] = origin->y-(h/2);//bottom left i0         varray[2] = origin->x-(w/2); varray[3] = origin->y+(h/2);//top left i1         varray[4] = origin->x+(w/2); varray[5] = origin->y+(h/2);//top right i2         varray[6] = origin->x+(w/2); varray[7] = origin->y-(h/2);//bottom right i3         break;      case bottomleft:          varray[0] = origin->x; varray[1] = origin->y;//bottom left i0         varray[2] = origin->x; varray[3] = origin->y+h;//top left i1         varray[4] = origin->x+w; varray[5] = origin->y+h;//top right i2         varray[6] = origin->x+w; varray[7] = origin->y;//bottom right i3          break;      case topleft:          varray[0] = origin->x; varray[1] = origin->y-h;//bottom left i0         varray[2] = origin->x; varray[3] = origin->y;//top left i1         varray[4] = origin->x+w; varray[5] = origin->y;//top right i2         varray[6] = origin->x+w; varray[7] = origin->y-h;//bottom right i3          break;      case topright:          varray[0] = origin->x-w; varray[1] = origin->y-h;//bottom left i0         varray[2] = origin->x-w; varray[3] = origin->y;//top left i1         varray[4] = origin->x; varray[5] = origin->y;//top right i2         varray[6] = origin->x; varray[7] = origin->y-h;//bottom right i3          break;      case bottomright:          varray[0] = origin->x-w; varray[1] = origin->y;//bottom left i0         varray[2] = origin->x-w; varray[3] = origin->y+h;//top left i1         varray[4] = origin->x-h; varray[5] = origin->y;//top right i2         varray[6] = origin->x; varray[7] = origin->y;//bottom right i3          break;      default: //same center          varray[0] = origin->x-(w/2); varray[1] = origin->y-(h/2);//bottom left i0         varray[2] = origin->x-(w/2); varray[3] = origin->y+(h/2);//top left i1         varray[4] = origin->x+(w/2); varray[5] = origin->y+(h/2);//top right i2         varray[6] = origin->x+(w/2); varray[7] = origin->y-(h/2);//bottom right i3          break;       } #pragma  endregion                //create quick texture array (we create on heap rather creating/destoying every cycle)     glfloat tarray[8] =      {         //this has been tinkered normal order. think lodepng bringing pd upside down. quick fix here necessary.         0.0f,1.0f,//0         0.0f,0.0f,//1         1.0f,0.0f,//2         1.0f,1.0f//3     };      //and finally.. index array...remember, draw in triangles....(and we'll go cw)     glubyte iarray[6] =     {         0,1,2,         0,2,3     };      //activate arrays     glenableclientstate(gl_vertex_array);     glenableclientstate(gl_texture_coord_array);      //give opengl pointer our varray , tarray     glvertexpointer(2, gl_float, 0, &varray[0]);     gltexcoordpointer(2, gl_float, 0, &tarray[0]);      //draw     gldrawelements(gl_triangles, 6, gl_unsigned_byte, &iarray[0]);      //gldrawarrays(gl_triangles,0,6);      //disable vertex arrays     gldisableclientstate(gl_vertex_array);     gldisableclientstate(gl_texture_coord_array);     gldisable(gl_texture_2d); } 

could tell me why opengl not loading , drawing new pixel data i've loaded it? said, suspect it's glgentextures not giving me new texture name.

you're calling glteximage2d , passing pointer client memory. beware, documentation says:

if non-zero named buffer object bound gl_pixel_unpack_buffer target (see glbindbuffer) while texture image specified, data treated byte offset buffer object's data store.

you may wish call glbindbuffer(gl_pixel_unpack_buffer, 0) unbind buffer object safe.