CODEWITHSUNDEEP
javalibgdxbox2d
Lordeblader
Lordeblader

Reputation: 96

How to stop a body's impulses and forces but not gravity in libGDX (Box2D)?

I'm making a plataformer game and now I'm making the player movements. So when I press 'A', the player moves to the left (player.moveLeft()); when I press 'D' the player moves to the rigth (player.moveRigth()); and when I press 'W', the player jumps (player.jump()).

public void moveLeft() {
    if(Gdx.input.isKeyPressed(Keys.A) &&
      !Gdx.input.isKeyPressed(Keys.D) &&
      body.getLinearVelocity().x > -MAXIMUM_VELOCITY){
        left = true;
        body.applyLinearImpulse(-3, 0, body.getPosition().x, body.getPosition().y, true);
    }else if(Gdx.input.isKeyPressed(Keys.D) &&
             Gdx.input.isKeyPressed(Keys.A) &&
             !inTheAir){
        stop();
    }else if(!Gdx.input.isKeyPressed(Keys.A) && 
             !Gdx.input.isKeyPressed(Keys.D) &&
             !inTheAir){
        stop();
    }
}

public void moveRigth() {
    if(Gdx.input.isKeyPressed(Keys.D) &&
      !Gdx.input.isKeyPressed(Keys.A) &&
      body.getLinearVelocity().x < MAXIMUM_VELOCITY){
        rigth = true;
        body.applyLinearImpulse(3, 0, body.getPosition().x, body.getPosition().y, true);
    }else if(Gdx.input.isKeyPressed(Keys.D) &&
             Gdx.input.isKeyPressed(Keys.A) &&
             !inTheAir){
        stop();
    }else if(!Gdx.input.isKeyPressed(Keys.D) &&
            !Gdx.input.isKeyPressed(Keys.A) &&
            !inTheAir){
        stop();
    }
}

public void stop(){
    body.setLinearVelocity(0, 0);
    body.setAngularVelocity(0);
}

public void jump(){
    if(!inTheAir && Gdx.input.isKeyPressed(Keys.W)){
        inTheAir = true;
        body.setLinearVelocity(0, 0);
        body.setAngularVelocity(0);
        body.applyLinearImpulse(0, 7, body.getPosition().x, body.getPosition().y, true);
    }
}

It works but I've got a problem: when I press 'A' or 'D' before jumping, and when the player is jumping and I release the key, the player keeps moving. How can I fix it?? Please help me!!

Upvotes: 1

Views: 947

Answers (1)

manabreak
manabreak

Reputation: 5597

You have to manipulate the X-axis velocity:

Vector2 vel = body.getLinearVelocity();
vel.x = 0f;
body.setLinearVelocity(vel);

This way, the Y-axis velocity remains the same, but your player won't move sideways.

Upvotes: 1

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