Confusing box2d forces

Question

Hello Friends. This is my demo game screen-shoot. Here i am using three buttons. Right-bottom button is used for jump and left-bottom buttons used for move left and right.

I have some questions 1) should i use linearImpuls for jump body?? 2) For move right and left which types of force i applied???

PLease tell me i am confusing to use linearImpuls, applyforce and linearVelocity.

Thanks in advance

Answer 1

To jump you should use linear impulse upwards. To run you have a couple of options. You could apply a force which wil over time increase velocity. You would then need to limit the maximum velocity. This is done by applying damping. You also want the player to come to a complete stop when not pressing left or right. This is done by applying friction. Set friction and damping quite high to make the controls feel responsive.

You could also instead make a velocity check to see if you are moving to the right or left and apply an impulse if not. This will lead to a bit more jerky behaviour though (which might on the other hand be what you want)

Answer 2

How can i set maximum speed?? Because i am set one force when i press move button

if (moveRight.active==YES) 
    {   
            ballBody->SetActive(true);
        b2Vec2 locationworld=b2Vec2(10,0);
            //b2Vec2 force=b2Vec2(1.0,0);
        double mass=ballBody->GetMass();

        ballBody->ApplyForce(mass*locationworld, ballBody->GetWorldCenter());
  //      ballBody->SetLinearDamping(1.2f);

        NSLog(@"Speed Of Velocity Right: %f",ballBody->GetLinearVelocity().x);
    }

This condition is in update method. So where i set maximum speed??