Simple L-System

gistfile1.cpp

struct State
{
	vector3df rotate;
	vector3df prevPoint;

	State() : rotate(vector3df()) {}
	State(const State& other) : rotate(other.rotate), prevPoint(other.prevPoint) { }
};

typedef std::vector<line3df> Lines;
typedef std::stack<State> States;
typedef std::map<char, std::string> Rules;

typedef std::function< void() > ActionFunction;
typedef std::map<char, ActionFunction> Actions;

std::string command;
Lines lines;
Rules rules;
Actions actions;

// Start data
command = "F";
rules['F'] = "F[+F]F[-F][F]";
float angle = 20;

State currentState;
States states;

states.push(currentState);

vector3df point;

actions['F'] = [&states, &lines]()
{
	vector3df point = states.top().prevPoint + vector3df(0, 10, 0);

	point.rotateYZBy(states.top().rotate.X, states.top().prevPoint);
	point.rotateXZBy(states.top().rotate.Y, states.top().prevPoint);
	point.rotateXYBy(states.top().rotate.Z, states.top().prevPoint);

	lines.push_back(line3df(point, states.top().prevPoint));
	states.top().prevPoint = point;
};

actions['+'] = [&states, &angle](){ states.top().rotate.X += angle; };
actions['-'] = [&states, &angle](){ states.top().rotate.X -= angle; };

actions['&'] = [&states, &angle](){ states.top().rotate.Y += angle; };
actions['^'] = [&states, &angle](){ states.top().rotate.Y -= angle; };

actions['\\'] = [&states, &angle](){ states.top().rotate.Z += angle; };
actions['/'] = [&states, &angle](){ states.top().rotate.Z -= angle; };

actions['['] = [&states, &angle](){ states.push(State(states.top())); };
actions[']'] = [&states, &angle](){ states.pop(); };

for(int i = 0; i < 5; ++i)
{
	std::string temp = "";

	for(auto it = command.begin(); it != command.end(); ++it)
	{
		if(rules.find(*it) != rules.end())
			temp += rules[*it];
		else
			temp += *it;
	}

	command = temp;
}

for(auto it = command.begin(); it != command.end(); ++it)
{
	if(actions.find(*it) != actions.end())
		actions[*it]();
}