How to achieve the following effect with libGDX? - libgdx

Question

I'm developping a game with libGDX. I have a question: Know the initial coordinates and target coordinates, as the picture shows, how to achieve the parabolic effect of the bullet ? to achieve the operation of shells . Who can teach me ? or tell me some tutorial. Tks
picture

Answer 1

You need to add some physics to your app (ex. Box2d). Then you 'throw' canon ball with some velocity and some direction/angle.
Physics engine do rest for you.
Here you have tutorial for box2d: https://www.youtube.com/watch?v=vXovY2KTing
Very very basic example for throw something without box2d. For your example you need to calculate right 'power' for target position.
public class SampleApp extends ApplicationAdapter
{
Sprite sprite;
Vector2 velocity = new Vector2(0, 0);
Vector2 terminateVelocity = new Vector2(2000, 2000);
Vector2 friction = new Vector2(200, 300);
Vector2 position = new Vector2(0, 0);
Vector2 launchPower = new Vector2(0, 0);
boolean shotNow;
#Override
public void render()
{
update(Gdx.graphics.getDeltaTime());
// ...
// here render your stuff
}
public void shot(float power)
{
// Calculate x launch power
launchPower.x = ((power - sprite.getX() + sprite.getWidth()*0.5f) / 2f) + velocity.x;
// We want to end our fly at ground
launchPower.y = ((0 - sprite.getY()) / 2f) + velocity.y;
// Setup start position
position.x = sprite.getX();
position.y = sprite.getY();
// Add some acc to velocity
velocity.add(launchPower);
shotNow = true;
}
public void update(float dt)
{
if (Gdx.input.justTouched()) {
shot(900);
}
// Very basic sprite movement.
// For best results you should implement more physics (acceleration etc.)
if (shotNow && position.y > 0) {
// Friction/gravity
velocity.x = MathUtils.clamp(velocity.x - friction.x * dt, -terminateVelocity.x, terminateVelocity.x);
velocity.y = MathUtils.clamp(velocity.y - friction.y * dt, -terminateVelocity.y, terminateVelocity.y);
position.add(velocity.x * dt, velocity.y * dt);
sprite.setPosition(position.x, position.y);
}
}
}