Adding the Actors - Learning LibGDX Game Development - page 189

We will now add simple physics simulation code that makes use of the new physics
attributes, namely, velocity , terminalVelocity , friction , and acceleration :

1. Add the following import to AbstractGameObject :

import com.badlogic.gdx.math.MathUtils;

2. Furthermore, add the following code to the same class:

protected void updateMotionX (float deltaTime) {
if (velocity.x != 0) {
// Apply friction
if (velocity.x > 0) {
velocity.x =
Math.max(velocity.x - friction.x * deltaTime, 0);
} else {
velocity.x =
Math.min(velocity.x + friction.x * deltaTime, 0);
}
}
// Apply acceleration
velocity.x += acceleration.x * deltaTime;
// Make sure the object's velocity does not exceed the
// positive or negative terminal velocity
velocity.x = MathUtils.clamp(velocity.x,
-terminalVelocity.x, terminalVelocity.x);
}

protected void updateMotionY (float deltaTime) {
if (velocity.y != 0) {
// Apply friction
if (velocity.y > 0) {
velocity.y = Math.max(velocity.y - friction.y *
deltaTime, 0);
} else {
velocity.y = Math.min(velocity.y + friction.y *
deltaTime, 0);
}
}
// Apply acceleration
velocity.y += acceleration.y * deltaTime;
// Make sure the object's velocity does not exceed the
// positive or negative terminal velocity