The parachute descends head down. How do you reverse it?

Question

I made a rocket in Unity that I can take off and land after five seconds. However, it lands that way:

I want to get him to the ground with his parachute up. How can I do that by code?

Code I have so far:

double t = 5.0;

void Update () {
GameObject Paraquedas;
GameObject CorpoNariz;
CorpoNariz = GameObject.Find("Corpo_Nariz");
Paraquedas = GameObject.Find("Paraquedas");
    rigidbody.AddForce(transform.up * 15);
    t -= Time.deltaTime;
    if (t <= 0) {
    Destroy (CorpoNariz);
    Paraquedas.renderer.enabled = true;
    rigidbody.AddForce(-transform.up * 50);
    rigidbody.drag = 5;
       }
   }
}

Answer 1

Here’s a hint of how you can do whatever you want (sorry, I did in C# by custom, but it’s trivial to convert to javascript):

using UnityEngine;
using System.Collections;

public class Disparar : MonoBehaviour {

    // Funçao de atualizaçao quadro a quadro
    void Update () {

        // So loga as informaçoes
        Debug.Log (rigidbody.velocity.magnitude);
        Debug.Log (noChao ());

        // Acelera se o jogador apertar a tecla ESPACO
        if(Input.GetKeyDown(KeyCode.Space))
            acelera ();

        // Quando detectar que a velocidade inverteu (ficou negativa no y e magnitude bem pequena,
        // ou seja, o foguete parou la no alto), aplica uma força para girar.
        if (!noChao () && rigidbody.velocity.y < 0 && rigidbody.velocity.magnitude <= 1)
            //gira();
            StartCoroutine(fazRetorno());
    }

    // Acelera se o jogador clicar no foguete
    void OnMouseDown() {
        acelera();
    }

    // Acelera o foguete aplicando uma força para a sua direçao "cima".
    void acelera() {
        rigidbody.AddForce(transform.up * 2000);
    }

    // Gira o foguete aplicando uma força para a sua direçao direita a partir de seu topo.
    void gira() {
        Vector3 ponta = transform.position;
        ponta.y += renderer.bounds.size.y / 2;
        rigidbody.AddForceAtPosition (transform.right * 20, ponta);
    }

    // Indica se o foguete esta colidindo com o chao
    bool noChao() {
        return Physics.Raycast(transform.position, -Vector3.up, collider.bounds.extents.y + 0.1f);
    }

    // Gira o foguete 180 graus sobre o eixo X, fazendo-o inverter completamente a direçao de subida
    IEnumerator fazRetorno() {

        Quaternion angulo = Quaternion.Euler(180, 0, 0);
        float velocidade = 0.5f;

        while(Quaternion.Angle(transform.rotation, angulo) > 0)
        {
            transform.rotation = Quaternion.Slerp(transform.rotation, angulo, Time.deltaTime * velocidade);
            yield return new WaitForEndOfFrame();
        }  
        transform.rotation = angulo;
    }

}

Basically the idea is that from a user interaction (click or keyboard), a force is added to the rocket (I tested it with a parallelepiped). At each frame, it checks whether the rocket has stopped up there (i.e., it is not on the ground and the speed on the y axis has been reversed and is small beeeemmm - meaning magnitude less than 1). If this happened, he simply applies another force to the top of the rocket to make it spin.

This example causes the rocket to rise vertically and decelerate until it stops high, so it will rotate and start to fall vertically as well. You will need to adjust the force values to get a cool effect as desired.

EDIT: I’ve done a new function called fazRetorno that doesn’t use physics and simply rotate the rocket without adding any force side. Maybe this is closer than you want. She uses Nice Unity features that are the command yield along with the function Quaternion.Slerp. Basically the execution of the loop (while) that has within the function fazRetorno is diluted over several tables (the yield does this) and the rotation to 180º on the x axis (the variable angulo indicates this) is "interpolated" according to the speed set in the variable velocidade. Although this rotation does not use physics, note that the "fall" of the rocket is all managed by the physics engine of the Unity (i.e., the only force added was at the beginning, at the time of the launching). :)

If your game wants the rocket to be launched on a ballistic trajectory (a parabola), simply combine the vectors to add the force on the y (top) and x or z (front and side) axes at the time of launch. To do this, just add the vectors:

Vector3 forca = (transform.up * 2000) + (transform.right * 300);
rigidbody.AddForce(forca);

Using the rigidbody.velocity you can know the speed of the rocket at any time, and you can decide to open the parachute. It’s another option.

I hope it helps.

P.S.: For this example your rocket must also have a collider (ideally a box collider) besides the rigidbody. :)