al_draw_filled_rectangle() seems to work only in some classes - c++

Question

I am trying to write a basic program with a game loop (it can't be called a game any time soon). Almost everything I have (which isn't much, frankly) is fine, just the one object in my render tree doesn't render!
The game loop:
void Game::enterMainLoop() {
running = true;
double lastTime = al_get_time();
std::cout << "Entering main loop!" << std::endl;
while (running) { // Never mind the infinite loop. This isn't the final version
double current = al_get_time();
double timePassed = current - lastTime;
processInput();
processUpdatables();
processPhysicalObjects();
processRenderables();
update(timePassed);
physics(timePassed);
render(renderTree);
lastTime = current;
}
}
I have verified it loops correctly (and quickly - the called methods don't do much).
The Game::render() method:
void Game::render(std::vector<IRenderable*> toRender) {
al_clear_to_color(al_map_rgb(0,0,90));
IRenderable *renderable;
for (std::vector<IRenderable*>::iterator it = toRender.begin(); it != toRender.end(); ++it) {
renderable = *it;
renderable->render();
render(renderable->getChildren());
}
al_draw_filled_rectangle(10, 10, 120, 120, al_map_rgb(255, 255, 255));
al_flip_display();
}
I verified the one object in the render tree's render method is called (by putting a cout statement in its body, which prints every frame). The filled rectangle is visible on screen.
The Player::render method at first drew a square at (this.x, this.y) with dimensions this.width x this.height, but I saw nothing on screen, so I simplified it to this:
void Player::render() {
std::cout << "Player::render called! x: " << x << ", y: " << y << std::endl;
al_draw_filled_rectangle(120, 120, 120, 120, al_map_rgb(255, 255, 255));
}
Yes, the cout statement prints every frame, so the render() method is called correctly. Yet I don't see a second rectangle.
Why can't I draw from the Player class?
(Note: everything compiles without output with -Wall enabled. During runtime I also don't have any output besides what I generate with cout statements.)

Answer 1

It cant realiably be deduced without a mcve, but from the code shown, and assuming renderable->getChildren() returns a std::vector, the problem is most propably related to the fact that after rendering one of the elements you always recurse and call al_clear_to_color as a result:
al_clear_to_color(al_map_rgb(0,0,90)); //1: clear screen
IRenderable *renderable;
for (std::vector<IRenderable*>::iterator it = toRender.begin(); it != toRender.end(); ++it) {
renderable = *it;
//renders one element
renderable->render();
//recurses and therefore reaches 1(clear screen) again(even if there are no children)
render(renderable->getChildren());
}