Question

I draw my background every frames :

void Window::paintGL()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    backgrd->Draw();

    texture = text->loadTexture(text->amis_path.toStdString(),text->w,text->h);
    amis->Draw();

    texture = text->loadTexture(text->enemis_path.toStdString(),text->w,text->h);
    for (int i = 0; i<liste_enemis.length(); i++){
        liste_enemis[i]->Draw();
    }

    for (int i = 0; i<liste_missiles.length(); i++){
        liste_missiles[i]->Draw();
    }
    swapBuffers();
}

But when I run the game, the fps a pretty bad (1fps).

Edit :

Well I’m trying to load my background in a texture one time but it doesn’t work :

Background::Background(int w, int h)
{
    width = w;
    height = h;
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexImage2D(GL_TEXTURE_2D,0, GL_RGBA, back.width(), back.height(), 0,
    GL_RGBA, GL_UNSIGNED_BYTE, back.bits());
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
}

void Background::Draw(){
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D,texture);
    glPushMatrix();
    glTranslatef(width/2, height/2, 0.0f);
    glBegin(GL_QUADS);
    glTexCoord2d(0,0); glVertex3f(-width/2, -height/2, 0.0f);
    glTexCoord2d(0,1); glVertex3f(-width/2, height/2, 0.0f);
    glTexCoord2d(1,1); glVertex3f(width/2, height/2, 0.0f);
    glTexCoord2d(1,0); glVertex3d(width/2, -height/2, 0.0f);
    glEnd();
    glPopMatrix();
}

The constructor load the background with glTexImage2D(…) and links it to the “texture” variable.
Then in my paintGL() function, I call the Background::Draw() function.

But when I run the game, there is no background.

If I move glTexParameteri(…) and glTexImage2D(…) functions from constructor to Draw function, it works.

Answer 1

You’re reloading the textures each and every frame, that’s what’s causing your performance it (it will also consume your memory in no time).

Instead of reloading the texture every frame, load them only once, and then switch between textures using glBindTexture