Be my fan on FacebookNew tile based platform engine – part 6 – ladders
- September 23, 2008 by Emanuele Feronato
- Filed under Actionscript 2, Flash, Game design | 25 Comments
It’s time to introduce ladders.
Ladders are quite hard to do for one reason: there is a lot of ways of intending ladders.
Can the player jump when on a ladder?
Should a ladder act as a hole if the player walks on it?
These are only two of the many questions you may ask about ladders.
So I have to made some rules:
1) Player climbs the ladder up and down using UP and DOWN arrows
2) Player can jump when on a ladder
3) If the player is falling and encounters a ladder, he will keep falling until he presses UP or DOWN
4) Player can climb a ladder if at least one of its corners is in the ladder
This is the actionscript
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 | 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, 0, 0, 0, 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, 0, 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; y<level_height; y++) {
for (x=0; x<level_width; x++) {
if (l[y][x] != 0) {
t = level_container.attachMovie("tile", "t"+y+"_"+x, _root.level_container.getNextHighestDepth(), {_x:x*tile_size, _y:y*tile_size});
t.gotoAndStop(l[y][x]);
}
}
}
x_pos = player[0]*tile_size+tile_size/2;
y_pos = player[1]*tile_size+tile_size/2+1;
level_container.attachMovie("hero", "hero", _root.level_container.getNextHighestDepth(), {_x:x_pos, _y:y_pos});
}
create_level(level);
_root.onEnterFrame = function() {
ground_under_feet();
walking = false;
climbing = false;
if (Key.isDown(Key.LEFT)) {
xspeed -= speed;
walking = true;
}
if (Key.isDown(Key.RIGHT)) {
xspeed += speed;
walking = true;
}
if (Key.isDown(Key.UP)) {
get_edges();
if (top_right == 6 or bottom_right == 6 or top_left == 6 or bottom_left == 6) {
jumping = false;
falling = false;
climbing = true;
climbdir = -1;
}
}
if (Key.isDown(Key.DOWN)) {
get_edges();
if (over == "ladder") {
jumping = false;
falling = false;
climbing = true;
climbdir = 1;
}
}
if (Key.isDown(Key.SPACE)) {
get_edges();
if (!falling and !jumping) {
jumping = true;
yspeed = -jump_speed;
}
}
if (!walking) {
xspeed *= friction;
if (Math.abs(xspeed)<0.5) {
xspeed = 0;
}
}
if (xspeed>max_speed) {
xspeed = max_speed;
}
if (xspeed<max_speed*-1) {
xspeed = max_speed*-1;
}
if (falling or jumping) {
yspeed += gravity;
}
if (climbing) {
yspeed = climb_speed*climbdir;
}
if (!falling and !jumping and !climbing) {
yspeed = 0;
}
xspeed += bonus_speed;
check_collisions();
level_container.hero._x = x_pos;
level_container.hero._y = y_pos;
xspeed -= bonus_speed;
};
function ground_under_feet() {
bonus_speed = 0;
left_foot_x = Math.floor((x_pos-6)/tile_size);
right_foot_x = Math.floor((x_pos+5)/tile_size);
foot_y = Math.floor((y_pos+9)/tile_size);
left_foot = level[foot_y][left_foot_x];
right_foot = level[foot_y][right_foot_x];
if (left_foot != 0) {
current_tile = left_foot;
} else {
current_tile = right_foot;
}
switch (current_tile) {
case 0 :
speed = air_acceleration;
friction = air_friction;
falling = true;
break;
case 1 :
over = "ground";
speed = ground_acceleration;
friction = ground_friction;
break;
case 2 :
over = "ice";
speed = ice_acceleration;
friction = ice_friction;
break;
case 3 :
over = "treadmill";
speed = ground_acceleration;
friction = ground_friction;
bonus_speed = -treadmill_speed;
break;
case 4 :
over = "treadmill";
speed = ground_acceleration;
friction = ground_friction;
bonus_speed = treadmill_speed;
break;
case 5 :
over = "cloud";
speed = ground_acceleration;
friction = ground_friction;
break;
case 6 :
over = "ladder";
speed = ground_acceleration;
friction = ground_friction;
break;
}
}
function check_collisions() {
y_pos += yspeed;
get_edges();
// collision to the bottom
if (yspeed>0) {
if ((bottom_right != 0 and bottom_right != 6) or (bottom_left != 0 and bottom_left != 6)) {
if (bottom_right != 5 and bottom_left != 5) {
y_pos = bottom*tile_size-9;
yspeed = 0;
falling = false;
jumping = false;
} else {
if (prev_bottom<bottom) {
y_pos = bottom*tile_size-9;
yspeed = 0;
falling = false;
jumping = false;
}
}
}
}
// collision to the top
if (yspeed<0) {
if ((top_right != 0 and top_right != 5 and top_right != 6) or (top_left != 0 and top_left != 5 and top_left != 6)) {
y_pos = bottom*tile_size+1+8;
yspeed = 0;
falling = false;
jumping = false;
}
}
x_pos += xspeed;
get_edges();
// collision to the left
if (xspeed<0) {
if ((top_left != 0 and top_left != 5 and top_left != 6) or (bottom_left != 0 and bottom_left != 5 and bottom_left != 6)) {
x_pos = (left+1)*tile_size+6;
xspeed = 0;
}
}
// collision to the right
if (xspeed>0) {
if ((top_right != 0 and top_right != 5 and top_right != 6) or (bottom_right != 0 and bottom_right != 5 and bottom_right != 6)) {
x_pos = right*tile_size-6;
xspeed = 0;
}
}
x_pos = Math.round(x_pos);
y_pos = Math.round(y_pos);
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
Any game on the horizon? I am making one…
Download the source code and enjoy.
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(24 votes, average: 4.75 out of 5)
(24 votes, average: 4.75 out of 5)
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25 Responses
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This is awesome! But is this the last part? You should add some spikes or something that would kill the player. And maybe comment on the code?
Top banana! Any news on the WordPress plugin Emanuele?
Is this the last one?
Its awesome but we need enemies!
Looks really impressive. A good engine so far in only 6 steps with lots of possibility.
Found a small glitch, when you run off the edge (where the ladders are) you can easily get back up on the ledge even when your falling off by running back towards it in mid-air.
I guess this could be fixed by having another side hitTest nearer his feet.
Good job!!!!!
But…I’m waiting in actionscript 3.0!!!!
i think this is a great engine and just what i need for my next game. this will be my first attempt at a tile based game but this tutorial will help me greatly.
things that could possibly be added…
spikes,enemys(plus kill, maybe by jumping on them.),left/right/jump animations,scrolling background.
with those added it will be an absoloutly brillantant game.
please reply if your do plan to add any of these features.
Found another glitch. While climbing down the ladder it’s possible to move left or right and still be climbing downwards as long as you continue to hold the down button.
Still, amazing work, it’s looking great so far. :)
Hi, i sugest you… that check collision in ladder when the player jumo and going down… isn’t ?
Yes, please do another step where the player dies…
IE: Spikes
This series of tutorials is fantastic.
I see so many possibilities.
Thank you!!!
Great stuff but I’m having issues, I you move to the right hand side of the screen and jump, you seem to get stuck on the wall. Any idea to fix this? Thnaks
From one game developer to another I’ll thank you again for doing this. You are an incredible coder and I’ve been following your work for a long time. Thanks a ton and get some sleep!
i don’t know if its a bug but you can walk on top of the ladder without falling,but if you jump the ladder become a “hole” and you’ll fall
One glitch is that you can float slowly downwards if you hold down and the last tile you touched is a ladder tile.
Another glitch If you jump and the top of your character hits a grey tile while still touching a ladder you float in midair until you aren’t touching ladder anymore. By the way this engine is awsome but for some reason if I make a square who is center aligned the hittests are way off. Do I need to make it to the exact dimensions of the one you have?
[...] This is the AS3 version of part 6. [...]
many thanks, it’s very useful
maybe, when going up ladders, it would be a good idea that you could only stay suspended on a ladder for a certain amount of time, or you fall down…?
Good tutorial :)
One of the best tutorials here! I have looked ~75% of your flash tutorials and I like the most of ‘em’. I’m making a little game for this. I made now exit and falling function (when you fall out from level). And I know i can make enemies and something like pipes so you only hit them from left and right so you can go downwards trough them. But yea, ladders have some bugs.
Looking great man. This is one of your best sets of tutorials. Really enjoying reading these keep em up.
[...] the AS3 translation of AS2 part 6, it’s time to introduce [...]
My spike code:
where you add tile add this:
case 1 :
over = “ground”;
x_pos = 40
y_pos = 40
break;
It’s exaple, change x and y of player by detecting em using variables. That’s how I also do falling:
if(y_pos >140 ){
y_pos = 40
x_pos = 40
}
It’s easy.
I can’t find the AS3 code where the “ladder bug” was fixed. I thought that maybe all I would have to do is make the:
if (Key.isDown(Key.DOWN)) {
get_edges();
if (over == “ladder”) {
jumping = false;
falling = false;
climbing = true;
climbdir = 1;
}
}
Turn into:
if (press_down)
{
get_edges();
if ((over == “ladder”) || (top_right == 6 || bottom_right == 6 || top_left == 6 || bottom_left == 6))
{
jumping = false;
falling = false;
climbing = true;
climbdir = 1;
}
}
this does not work either. :( I really want to use this tile based idea but being able to make different tile images for the ladder is very important for what I am making. Thanks for responding before!
Evan
[...] bug appeared in part 6 and was fixed in part [...]
I am trying to add a second type of ladder. This ladder is the exact same thing but the image is of a different color of ladder. I simply made it on frame 8 of the block movie clip and added the case 8 code that is the exact same as the case 7 code in the as file. It does not work. With trace statements all the code is running right but the character does not move up or down when it hits the new ladder block any ideas?