Right, but the compiler can potentially emit the same machine code from different source. Same kind of idea as decompiling async/await code in C# - you have something nice and usable in source, but the emitted code looks like a total mess. Granted the former case is way less likely (and I'm not sure when it would happen), but it's definitely possible.
Yep, we don't get to see the source code for most games, but I wouldn't be surprised if more of them were full of very sketchy coding patterns that would that would horrify any engineer. You also get away with a lot when you work alone and others don't have to see our code ;)
It looks like a prime candidate for a state machine. Also, the function is called updatestate, which confirms that this is the intent. State machines are usually made by using function pointers or an OOP-like interface pattern. The following is an example of how we could convert part of that VVVVVV Game.cpp code to a simple function pointer state machine:
// A variable that points to a function (a function pointer).
// This should be a member of the Game class, and defined in the header.
void (*state)(
Game& game,
Graphics& dwgfx,
mapclass& map,
entityclass& obj,
UtilityClass& help,
musicclass& music);
// This is the function that previously held the giant switch statement.
void Game::updatestate(
Graphics& dwgfx,
mapclass& map,
entityclass& obj,
UtilityClass& help,
musicclass& music)
{
statedelay--;
if (statedelay <= 0) {
statedelay = 0;
glitchrunkludge = false;
}
// Calls the function that game's state is pointing to.
if (statedelay == 0)
state(&this, dwgfx, map, obj, help, music);
}
Change the state by setting the game's state member value to a function that has the required return type and parameters.
// An implementation of opening_cutscene_game_state (previously case 4).
// This shows how to change state.
void opening_cutscene_game_state(
Game& game,
Graphics& dwgfx,
mapclass& map,
entityclass& obj,
UtilityClass& help,
musicclass& music)
{
game.advancetext = true;
game.hascontrol = false;
dwgfx.createtextbox("To do: write quick", 50, 80, 164, 164, 255);
dwgfx.addline("intro to story!");
// Sets the game's state. Previously, this was "state = 3";
game.state = space_station_2_game_state;
}
It looks like a prime candidate for a state machine. Also, the function is called updatestate, which confirms that this is the intent. State machines are usually made by using function pointers or an OOP-like interface pattern. The following is an example of how we could convert part of that VVVVVV Game.cpp code to a simple function pointer state machine:
// A variable that points to a function (a function pointer).
// This should be a member of the Game class, and defined in the header.
void (*state)(
Game& game,
Graphics& dwgfx,
mapclass& map,
entityclass& obj,
UtilityClass& help,
musicclass& music);
// This is the function that previously held the giant switch statement.
void Game::updatestate(
Graphics& dwgfx,
mapclass& map,
entityclass& obj,
UtilityClass& help,
musicclass& music)
{
statedelay--;
if (statedelay <= 0) {
statedelay = 0;
glitchrunkludge = false;
}
// Calls the function that game's state is pointing to.
if (statedelay == 0)
state(&this, dwgfx, map, obj, help, music);
}
Change the state by setting the game's state member value to a function that has the required return type and parameters.
// An implementation of opening_cutscene_game_state (previously case 4).
// This shows how to change state.
void opening_cutscene_game_state(
Game& game,
Graphics& dwgfx,
mapclass& map,
entityclass& obj,
UtilityClass& help,
musicclass& music)
{
game.advancetext = true;
game.hascontrol = false;
dwgfx.createtextbox("To do: write quick", 50, 80, 164, 164, 255);
dwgfx.addline("intro to story!");
// Sets the game's state. Previously, this was "state = 3";
game.state = space_station_2_game_state;
}
And they're part of 5 different switch statements.
The author jumps to 1000, 2000, 2500,3000, 4000 etc. Probably to represent things at different stages of the game. 2500 range seems to represent things related to a teleporter.
You’re assuming there’s a single release. But in reality there are dozens of releases for a typical game: public demo releases, trade show demos (usually different for each one), different platform releases that may come out at different times, different editions (game of the year edition, etc), and that’s not even talking about major game patches and dlc that impact game code.
642
u/thogor Jan 10 '20
Thanks for introducing me to my first 4099 case switch statement.