How to add a jumping mechanic to a game?

[nightm4re94]

^{This post has been migrated automatically from the old LITIENGINE forum (2018 - 2022).
Posted: 2018-12-19 20:21:51
User: Dmartin42 [] (age: 1435 days 🔥; posts: 36)}
Hello,
I have made a platformer but cannot figure out how to add a jumping mechanic. It is currently setup as follows:
The player presses 'space' and I move the entity up ten and let my GravityForce bring them back down.
private void jump(Creature player) { { Point2D jumpHeight = new Point2D.Double(player.getX(), player.getY()-10); player.setMoveDestination(jumpHeight); Game.getPhysicsEngine().move(player, player.getMoveDestination()); }
However, I want it so that the player can ONLY jump if they have collision with an entity or a static collision box. I have tried the game.getPhysics.collide() method in many ways but still cant figure it out. If anyone has suggestions, that would be great.

[nightm4re94]

^{This post has been migrated automatically from the old LITIENGINE forum (2018 - 2022).
Posted: 2018-12-19 21:35:51
User: CalvinMT [] (age: 1451 days 🔥; posts: 114)}
Dmartin42
You can try using "player.getBoundingBox().intersects()" in an "if" that'll be surrounding your jump code.
If true: jump. If not: nothing.
Might cost a bit though, especially if you need to go through all collidable objects... :/

[nightm4re94]

^{This post has been migrated automatically from the old LITIENGINE forum (2018 - 2022).
Posted: 2018-12-20 00:56:07
User: steffen [Admin 👑, Mod 🔧] (age: 1568 days 🔥; posts: 100)}
Dmartin42
> ... ONLY jump if they have collision with an entity or a static collision box
Technically, that should never be the case because that would mean that the collision was not properly resolved previously and the entity would be stuck in a collision box.
I think what you might be looking for is something like: if the player is touching the ground or another entity.
Depending on how you configured your player's collision and size properties, you should be able to use the player's ~~~~bounding box if it's bigger than the ~~collision box and do as CalvinMT suggested. You can just use the ~~PhysicsEngine for this, too:
~~```java~~if(Game.getPhysicsEngine().collides(player.getBoundingBox())){ // allow jump }```` You can configure your player's collision and size properties like so: java~~player.setCollisionBoxHeight(collisionBoxHeight); player.setCollisionBoxWidth(collisionBoxHeight); player.setWidth(boundingBoxWidth); player.setHeight(boundingBoxHeight);```` Another option would be to write a custom class for your player that extends ~~`~~Creature` and uses annotations. `~~@EntityInfo(width = 16, height = 16)
@CollisionInfo(collision = true, collisionBoxHeight = 4, collisionBoxWidth = 8)
public class MyPlayer extends Creature{
...
} Also, I highly recommend enabling some debug rendering if you're playing around with ~~`~~collision boxes` and ~~`~~bounding boxes`. Go to the ~~`~~game.properties` file and set `~~```~~dbg_debugEnabled=true dbg_renderBoundingBoxes=true dbg_renderCollisionBoxes=true

[nightm4re94]

^{This post has been migrated automatically from the old LITIENGINE forum (2018 - 2022).
Posted: 2018-12-20 17:32:56
User: Dmartin42 [] (age: 1435 days 🔥; posts: 36)}
steffen
Thank you. I did this and it still doesn't work. Here is my code:
if( (Game.getPhysicsEngine().collides(player.getBoundingBox(),CollisionType.STATIC)) ||
(Game.getPhysicsEngine().collides(player.getBoundingBox(),CollisionType.ENTITY)) ){
Point2D jumpHeight = new Point2D.Double(player.getX(), player.getY()-10);
player.setMoveDestination(jumpHeight);
Game.getPhysicsEngine().move(player, player.getMoveDestination());
}
I am still able to jump mid-air because it thinks the moving player is colliding with itself. Is there a way around this?

[nightm4re94]

^{This post has been migrated automatically from the old LITIENGINE forum (2018 - 2022).
Posted: 2018-12-20 17:44:51
User: steffen [Admin 👑, Mod 🔧] (age: 1568 days 🔥; posts: 100)}
Dmartin42 you could just use the method overload
~~```java~~ if(Game.getPhysicsEngine().collides(player.getBoundingBox(), player)){ Point2D jumpHeight = new Point2D.Double(player.getX(), player.getY()-10); player.setMoveDestination(jumpHeight); Game.getPhysicsEngine().move(player, player.getMoveDestination()); }```` This will explicitly exclude the specified entity from the collision detection. I think we could improve the ~~~~PhysicsEninge` API a bit for such scenarios.

[nightm4re94]

^{This post has been migrated automatically from the old LITIENGINE forum (2018 - 2022).
Posted: 2018-12-20 19:33:28
User: Dmartin42 [] (age: 1435 days 🔥; posts: 36)}
steffen
Steffen,
The use of overloading does not work because .getBoundingBox returns a rectangle and not a point. Is there any way around these things?

[nightm4re94]

^{This post has been migrated automatically from the old LITIENGINE forum (2018 - 2022).
Posted: 2018-12-20 19:50:53
User: steffen [Admin 👑, Mod 🔧] (age: 1568 days 🔥; posts: 100)}
Dmartin42 Damn, you're right... such a method is not available in 0.4.14 😢
It will be in the next version.
Another workaround would be to check entity collision manually.
`~~```~~if(Game.getPhysicsEngine().collides(player.getBoundingBox(), CollisionType.STATIC)
|| Game.getPhysicsEngine().getCollisionEntities().stream().anyMatch(e -> !e.equals(player) && e.getCollisionBox().intersects(player.getBoundingBox))){
Point2D jumpHeight = new Point2D.Double(player.getX(), player.getY()-10);
player.setMoveDestination(jumpHeight);
Game.getPhysicsEngine().move(player, player.getMoveDestination());
}````
From LITIengine 0.4.15 onward, the syntax for this will be as described in my previous post.

[nightm4re94]

^{This post has been migrated automatically from the old LITIENGINE forum (2018 - 2022).
Posted: 2019-01-04 12:50:35
User: nightm4re [Admin 👑, Mod 🔧] (age: 1567 days 🔥; posts: 185)}
Dmartin42 In case you haven't already seen it: there's a ~~~~Jump implemented in our new sample platformer project Gurk Nukem.