470 : Moving platforms
Balthazar:
We need a new platform image.
wheel.png
Copy the following files into your project:
- images/backgrounds/wheel.png
function init_level3() {
...
add_default_platforms(level);
var platform_data = [
// [x, y, width, height, pattern]
...
];
add_platforms(level, platform_data);
var moving_platform_data = [
// [x, y, width, height, pattern, min_x, max_x, move_x]
[400, 50, 30, 10, "wheel", 350, 490, -1],
[350, 180, 20, 10, "wheel", 300, 480, 0.5],
];
add_moving_platforms(level, moving_platform_data);
...
}
var moving_platform_data = [
// [x, y, width, height, pattern, min_x, max_x, move_x]
[400, 50, 30, 10, "wheel", 350, 490, -1],
[350, 180, 20, 10, "wheel", 300, 480, 0.5],
];
add_moving_platforms(level, moving_platform_data);
...
}
function add_default_platforms(level) {
...
}
// platform_data: [x, y, width, height, pattern, min_x, max_x, move_x]
function add_moving_platforms(level, platform_data) {
for (var i = 0; i < platform_data.length; i++) {
var p = platform_data[i];
var plat = create_platform(p[0], p[1], p[2], p[3], p[4]);
plat.moving = true;
plat.min_x = platform_data[i][5];
plat.max_x = platform_data[i][6];
plat.move_x = platform_data[i][7];
level.platforms.push(plat);
}
}
// platform_data: [x, y, width, height, pattern, min_x, max_x, move_x]
function add_moving_platforms(level, platform_data) {
for (var i = 0; i < platform_data.length; i++) {
var p = platform_data[i];
var plat = create_platform(p[0], p[1], p[2], p[3], p[4]);
plat.moving = true;
plat.min_x = platform_data[i][5];
plat.max_x = platform_data[i][6];
plat.move_x = platform_data[i][7];
level.platforms.push(plat);
}
}
function create_platform(x, y, width, height, pattern) {
...
p.width = width;
p.height = height;
p.origin_x = 0;
p.origin_y = 0;
p.dir = 1;
p.moving = false;
...
}
p.moving = false;
...
}
function draw_transition_screen() {
...
}
function update_platforms() {
var platforms = _levels[_game.current_level].platforms;
for (var i = 0; i < platforms.length; i++) {
var p = platforms[i];
if (p.moving) {
p.x += p.move_x;
if (p.x <= p.min_x || p.x >= p.max_x) {
p.move_x *= -1;
}
}
}
}
function update_monsters() {
...
}
function update_platforms() {
var platforms = _levels[_game.current_level].platforms;
for (var i = 0; i < platforms.length; i++) {
var p = platforms[i];
if (p.moving) {
p.x += p.move_x;
if (p.x <= p.min_x || p.x >= p.max_x) {
p.move_x *= -1;
}
}
}
}
function update_monsters() {
...
}
function update_world() {
var level = _levels[_game.current_level];
if (_game.in_transition) {
draw_transition_screen();
} else if (level.type == "game") {
update_monsters();
update_platforms();
update_items();
update_player();
check_collisions();
draw();
} else if (level.type == "title") {
draw_title_screen();
}
requestAnimationFrame(update_world);
}
update_platforms();
update_items();
update_player();
check_collisions();
draw();
} else if (level.type == "title") {
draw_title_screen();
}
requestAnimationFrame(update_world);
}
Balthazar:
If the player is on a moving platform, it needs to move along with the platform.
function update_player() {
...
// Move the player to the new location.
_player.x += _player.velocity_x;
_player.y += _player.velocity_y;
// If the player is on a moving platform, then the player should move along
// with the platform.
if (_player.platform && _player.platform.moving) {
_player.x += _player.platform.move_x;
}
}
// If the player is on a moving platform, then the player should move along
// with the platform.
if (_player.platform && _player.platform.moving) {
_player.x += _player.platform.move_x;
}
}
Congratulations! You've earned the Platform IV - Moving badge!