028 : No double jumps
You:
Yay! We can jump.
You:
well... sort of...
You:
If I hold the jump button down, I can fly off the top of the screen.
Balthazar:
Yes, apparently you can jump while you're in mid-air, which is not quite what we want. How do you think we should fix that?
You:
You should only be allowed to jump if you're standing on a platform.
Balthazar:
So we should add a variable to the player that keeps track of whether-or-not the player is currently on a platform.
script.js: Add a platform variable to the player.
function init_player() {
...
_player.origin_x = _player.width / 2;
_player.origin_y = _player.height;
_player.platform = false;
_player.velocity_x = 0;
_player.velocity_x_delta = 0.8;
...
}
_player.platform = false;
_player.velocity_x = 0;
_player.velocity_x_delta = 0.8;
...
}
Balthazar:
And we need to check this variable whenever the player tries to jump.
script.js: Only allow jumps if the player is on a platform.
function check_input() {
...
// Up arrow, 'w' and spacebar to jump.
if (_game.keymap[38] || _game.keymap[87] || _game.keymap[32]) {
// Only allow jumps if the player is on a platform.
if (_player.platform) {
_player.platform = false;
_player.velocity_y = _player.velocity_y_jump;
}
}
...
}
// Only allow jumps if the player is on a platform.
if (_player.platform) {
_player.platform = false;
_player.velocity_y = _player.velocity_y_jump;
}
}
...
}
You:
It doesn't seem to work yet.
Balthazar:
That's because we're not quite done. We now need to set the platform variable when the player is on a platform.
GOTO 033 if you already have the Collision I - Basic badge.