CODEWITHSUNDEEP
javalibgdxbox2dphysics
JohnDev
JohnDev

Reputation: 19

Increase body speed with applyLinearImpulse box2d

Im trying to make body move with increaseing speed. At first its starts to accelerate but it reaches a constant speed shortly after. How do I make it keep accelearte?

My code looks like this: 

 world = new World(new Vector2(0, 0), true);

    if (Gdx.input.isKeyPressed(Input.Keys.D))
        body.applyLinearImpulse(400f, 0, pos.x, pos.y, true);
    if (Gdx.input.isKeyPressed(Input.Keys.A))
        body.applyLinearImpulse(-400f, 0, pos.x, pos.y, true);
    if (Gdx.input.isKeyPressed(Input.Keys.W))
        body.applyLinearImpulse(0, 400f, pos.x, pos.y, true);
    if (Gdx.input.isKeyPressed(Input.Keys.S))
        body.applyLinearImpulse(0, -400f, pos.x, pos.y, true);

Upvotes: 0

Views: 2208

Answers (1)

Robert P
Robert P

Reputation: 9783

To make a Body accelerate over time, usualy applyForce is used, applyLinearImpulse is used for immediate speed changes instead.
Remeber, that you have to call applyForce, as long as you want to accellerate, while an impulse is usually only applied once.
Think about a starting car: The rotation of the wheels, combined with the friction adds a force to the whole car, accelerating it.
If the car then has got some speed and hits a box, an impulse is applied to the box once, increasing it's speed almost immediately.
So you could try to change the applyLinearImpulse call to applyForce and make sure it get's called every update cycle, as long as you press the given key.

I suggest you to read the Box2D tutorials on iforce2d.net

Upvotes: 1

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