Snake game: fast response vs. collision bug - c++

Question

I have a snake game in SFML C++, and I'm stuck between two options. If set the controls like this:
if(event.type == sf::Event::KeyPressed && (event.key.code == sf::Keyboard::Up
|| event.key.code == sf::Keyboard::W) && move != Down)
move = Up;
else if(event.type == sf::Event::KeyPressed && (event.key.code == sf::Keyboard::Down
|| event.key.code == sf::Keyboard::S) && move != Up)
move = Down;
else if(event.type == sf::Event::KeyPressed && (event.key.code == sf::Keyboard::Left
|| event.key.code == sf::Keyboard::A)&& move != Right)
move = Left;
else if(event.type == sf::Event::KeyPressed && (event.key.code == sf::Keyboard::Right
|| event.key.code == sf::Keyboard::D) && move != Left)
move = Right;
Here, the controls are very responsive. The problem is that if, for instance, the snake were going rightward and you were to press Up and then Left in extremely quick succession, the snake will not have moved upward yet, but the upward control will be buffered so the snake will be allowed to move leftward into itself, thus dying.
If instead I wrap these movement conditions in an if statement that only allows updating once per frame the bug is resolved, but the controls are much less smooth and responsive.
So my question is, how do I maintain the responsiveness of allowing the movement to update quickly while avoiding the bug of moving into itself?

Answer 1

Being that your making Snake; The problem lies not with your input(but those "if's" should be a switch statement) but within the Object that reacts with the input, ex. the "Snake_Object". The normal game forces a set number of positional movement when a direction is pressed. If you watch the game, if you press up then the snake is immediately forced up one collision box above where it was from before. This insures that you can not do your unwanted immediate collision and still keeps regular fps flow.
So when the move variable is sent to the Snake it should in the very first instance move a whole collision box in that direction and then move at normal speed.

Answer 2

I have no experience in game development, and I am not even sure I understand your question.
However, I wonder if the following structure for your code would help controlling the update process:
inline void UpdateMoveUp(Move& move) { if(move != Down) { move = Up; }}
inline void UpdateMoveDown(Move& move) { if(move != Up) { move = Down; }}
inline void UpdateMoveLeft(Move& move) { if(move != Right) { move = Left; }}
inline void UpdateMoveRight(Move& move) { if(move != Left) { move = Right; }}
inline void UpdateMoveInvalid(Move& move) { move = Invalid; }
inline void HandleUpdate(const Code& code, Move& move) {
switch(code) {
case sf::Keyboard::Up:
return UpdateMoveUp(move);
case sf::Keyboard::W:
return UpdateMoveUp(move);
case sf::Keyboard::Down:
return UpdateMoveDown(move);
case sf::Keyboard::S:
return UpdateMoveDown(move);
case sf::Keyboard::Left:
return UpdateMoveLeft(move);
case sf::Keyboard::A:
return UpdateMoveLeft(move);
case sf::Keyboard::Right:
return UpdateMoveRight(move);
case sf::Keyboard::D:
return UpdateMoveRight(move);
default:
return UpdateMoveInvalid(move);
}
}
void HandleInput(const Event& event, Move& move) {
// I assume that `move` comes from somewhere else
if(event.type == sf::Event::KeyPressed) {
return HandleUpdate(event.key.code, move);
}
}
The way I look at it is that you are isolating the update function to a single place, and you can add more conditions to the update there without having to test the whole condition again.
In other words, you could add further conditions to each UpdateMoveXXXX function, such as unbuffer and update or save timestamp and move (then move only if last timestamp minus current timestamp is more/less than some number).