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#include "model.hpp"
#include <lager/util.hpp>
#include <boost/config.hpp>
#include <boost/variant.hpp>
#include <algorithm>
namespace sn {
namespace {
template <typename T>
T wrap(T val, T min, T max)
{
if (val < min)
return max - (min - val) + 1;
if (val > max)
return min + (val - max) - 1;
return val;
}
direction left(direction initial)
{
if (initial == direction::up || initial == direction::down)
return direction::left;
return initial;
}
direction right(direction initial)
{
if (initial == direction::up || initial == direction::down)
return direction::right;
return initial;
}
direction up(direction initial)
{
if (initial == direction::left || initial == direction::right)
return direction::up;
return initial;
}
direction down(direction initial)
{
if (initial == direction::left || initial == direction::right)
return direction::down;
return initial;
}
point_t move_forward(point_t pos, direction dir)
{
switch (dir) {
case direction::left:
return {x(pos) - 1, y(pos)};
case direction::up:
return {x(pos), y(pos) - 1};
case direction::right:
return {x(pos) + 1, y(pos)};
case direction::down:
return {x(pos), y(pos) + 1};
}
BOOST_UNREACHABLE_RETURN(pos);
}
snake_model::body_t move_forward(snake_model::body_t body, direction dir)
{
const auto head = move_forward(body.front(), dir);
std::rotate(body.begin(), body.end() - 1, body.end());
body[0] = head;
return body;
}
bool in_bounds(point_t p)
{
return x(p) >= 0 && x(p) < game_model::width && y(p) >= 0 &&
y(p) < game_model::height;
}
template <typename Func>
game_model make_game(Func&& random)
{
const point_t snake_head{game_model::width / 2, game_model::height / 2};
snake_model::body_t body{snake_head,
{x(snake_head) - 1, y(snake_head)},
{x(snake_head) - 2, y(snake_head)}};
return {snake_model{body, direction::right},
random_apple_pos(std::forward<Func>(random)),
false};
}
} // namespace
app_model make_initial(int seed)
{
std::mt19937 gen{unsigned(seed)};
std::uniform_int_distribution<> dist{0, game_model::width - 1};
return {gen, dist, make_game([&] { return dist(gen); })};
}
app_model update(app_model m, action_t action)
{
return boost::apply_visitor(
lager::visitor{
[&](go_left) {
m.game.snake.dir = left(m.game.snake.dir);
return m;
},
[&](go_right) {
m.game.snake.dir = right(m.game.snake.dir);
return m;
},
[&](go_up) {
m.game.snake.dir = up(m.game.snake.dir);
return m;
},
[&](go_down) {
m.game.snake.dir = down(m.game.snake.dir);
return m;
},
[&](tick) {
const auto prev_back = m.game.snake.body.back();
auto body = move_forward(m.game.snake.body, m.game.snake.dir);
const auto head = body.front();
if (std::any_of(body.begin() + 1,
body.end(),
[&](const auto& p) { return p == head; }) ||
!in_bounds(head)) {
m.game.over = true;
return m;
}
if (prev_back == m.game.apple_pos) {
body.push_back(prev_back);
m.game.apple_pos =
random_apple_pos([&] { return m.dist(m.gen); });
}
m.game.snake.body = body;
return m;
},
[&](reset) {
m.game = make_game([&] { return m.dist(m.gen); });
return m;
}},
action);
}
} // namespace sn
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