New tile based platform engine – part 7 – trampolines

After the AS3 translation of AS2 part 6, it’s time to introduce trampolines.

Just like ladders, trampolines have their rules. Here they are:

1 – A trampoline does not act like a wall, so a player can walk through it just like a cloud

2 – A trampoline should never be placed over another trampoline

3 – When you land on a trampoline, your vertical speed is inverted

How does this affect gameplay?

Just try to play and reach that unreachable platform as shown in the picture

Here it is the actionscript:

tile_size = 20;
ground_acceleration = 1;
ground_friction = 0.8;
air_acceleration = 0.5;
air_friction = 0.7;
ice_acceleration = 0.15;
ice_friction = 0.95;
treadmill_speed = 2;
max_speed = 3;
xspeed = 0;
yspeed = 0;
falling = false;
gravity = 0.5;
jump_speed = 6;
climbing = false;
climb_speed = 0.8;
level = new Array();
level[0] = [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1];
level[1] = [1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1];
level[2] = [1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6, 1, 0, 0, 0, 0, 1];
level[3] = [1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 1];
level[4] = [1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 1];
level[5] = [1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 1];
level[6] = [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6, 1, 0, 0, 0, 0, 0, 1];
level[7] = [1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 1];
level[8] = [1, 1, 1, 1, 0, 0, 0, 0, 0, 5, 5, 0, 0, 0, 7, 0, 0, 6, 0, 0, 0, 0, 0, 0, 1];
level[9] = [1, 1, 1, 1, 3, 3, 3, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 4, 4, 4, 4, 1, 1];
player = [5, 1];
function create_level(l) {
	_root.createEmptyMovieClip("level_container", 1);
	level_height = l.length;
	level_width = l[0].length;
	for (y=0; ymax_speed) {
		xspeed = max_speed;
	}
	if (xspeed0) {
		if ((bottom_right != 0 and bottom_right != 6) or (bottom_left != 0 and bottom_left != 6)) {
			// not a cloud...
			if (bottom_right != 5 and bottom_left != 5) {
				// a trampoline
				if ((bottom_right == 7 or bottom_left == 7) and (Math.abs(yspeed)>1)) {
					yspeed = yspeed*-1;
					jumping = true;
					falling = true;
				} else {
					y_pos = bottom*tile_size-9;
					yspeed = 0;
					falling = false;
					jumping = false;
				}
			} else {
				//cloud
				if (prev_bottom0) {
		if ((top_right != 0 and top_right != 5 and top_right != 6 and top_right != 7) or (bottom_right != 0 and bottom_right != 5 and bottom_right != 6 and bottom_right != 7)) {
			x_pos = right*tile_size-6;
			xspeed = 0;
		}
	}
	prev_bottom = bottom;
}
function get_edges() {
	// right edge
	right = Math.floor((x_pos+5)/tile_size);
	// left edge   
	left = Math.floor((x_pos-6)/tile_size);
	// bottom edge
	bottom = Math.floor((y_pos+8)/tile_size);
	// top edge
	top = Math.floor((y_pos-9)/tile_size);
	// adjacent tiles
	top_right = level[top][right];
	top_left = level[top][left];
	bottom_left = level[bottom][left];
	bottom_right = level[bottom][right];
}

And this is the result:

Download the source code and enjoy.