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In Topic: C++ Tile Engine from Scratch -- Part 3

Posted 28 Jul 2011
Your tutorial is nice, but you're missing some potential pitfalls:
- you create several instances of Tile objects dynamically, but you never delete them anywhere in your code, which could lead to memory leaks;
- let's say we have a map smaller than the screen we're using (like in Pokemon, for example) - the draw tiles loop in Engine::RenderFrame() doesn't take into account the actual size of the map (which could be really small), only the screen resolution - you'll be accessing invalid memory regions;
- you don't place restrictions on the Camera target values - if someone tried to click "indefinitely" to reach the edge of the map, eventually target values become invalid and you'll be accessing invalid memory regions.
More than code about tiling engines, I think everyone would appreciate if you put code that avoids problems like memory leaks and accessing invalid memory addresses.

But keep up the good work. Started this tutorial yesterday and I can't wait for the other parts

PS: Try replacing the operator[] with function Vector::at() when you're accessing vector positions. Invalid memory access errors aren't masked this way and are easier to detect.
In Topic: C++ Tile Engine from Scratch -- Part 4

Posted 28 Jul 2011
keelx, on 26 July 2011 - 07:46 PM, said:
DarkGlitch, on 26 July 2011 - 07:12 AM, said:
I get an error saying this bit of code:

if((evt.Type == sf::Event::MouseButtonPressed) && (mouseDown == false)) { int x = camera->GetPosition().x + window->GetInput().GetMouseX(); int y = camera->GetPosition().y + window->GetInput().GetMouseY(); camera->GoToCenter(x, y); mouseDown = true; }

Is broken. My compiler says sf::RenderWindow doesn't have any members named GetInput(). And it doesn't. When I open the file there is no GetInput member. Help?

I downloaded the attached code due to my problems I posted in the previous posts for this tutorial.
Change window->GetInput to window->GetEvent.
I suppose you're talking about evt.MouseButton. Put it like this and it should work (I used another method on part 3, but tested and seemed fine).
```
if((evt.Type == sf::Event::MouseButtonPressed) && (mouseDown == false))
{
	int x = camera->GetPosition().x + evt.MouseButton.X;
	int y = camera->GetPosition().y + evt.MouseButton.Y;
	camera->GoToCenter(x, y);
	mouseDown = true;
}
```
There is also another solution. I had this problem on part 3, so I read the documentation for SFML 2.0 here (bro tip, always read the documentation first when searching for an API function ) and there is another way (this is what I'm currently using):
```
if((evt.Type == sf::Event::MouseButtonPressed) && (mouseDown == false))
{
	sf::Vector2i mousePos = sf::Mouse::GetPosition(*window);
	int x = camera->getPosition().x + mousePos.x;
	int y = camera->getPosition().y + mousePos.y;
	camera->goToCenter(x, y);
	mouseDown = true;
}
```
Also, don't know if anyone else noticed it too but the tutorial doesn't warn about scrolling near the map limits. Be sure to handle that or you'll be having some unexpected crashes.