Make a object move forwards

Question

I am trying to make an object move forwards, so I used this bit of code:

rigidbody.AddForce(Vector3.forward * speed, ForceMode.Force);

But it will only move in the Z direction. I read online that Vector3.forward is just shorthand for the Z axis so that makes sense, but is there a way of moving in the actual forward direction? Also I have one more question/bug, after it moves a ways it will start going really slowly, even when the speed is supposedly still at a high number.

Here is the whole script:

 #pragma strict
 
 var speed : float;
 
 var maxSpeed : float;
 
 var acceleration : float;
 
 function Start () {
 
 }
 
 function Update () {
 
 }
 
 function FixedUpdate(){
 
 if(Input.GetKey("w")){
 
 if(speed < maxSpeed){
 
 speed += acceleration;
 
 rigidbody.AddForce(Vector3.forward * speed, ForceMode.Force);
 
 }
 
 }
 
 if(Input.GetKey("a")){
 
 transform.Rotate(-Vector3(0, 1, 0));
 
 }
 
 if(Input.GetKey("d")){
 
 transform.Rotate(Vector3(0, 1, 0));
 
 }
 
 }

Answer 1

Best Answer

Answer by moxiewhimsy · Mar 26, 2014 at 05:26 PM

replace

 rigidbody.AddForce(Vector3.forward * speed, ForceMode.Force);

with

 rigidbody.AddForce(transform.forward * speed, ForceMode.Force);

You want the object's forward and not the world's forward.

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nicedude80 · Mar 26, 2014 at 05:35 PM 0

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Thanks that worked great. The only thing now is that the boat kindof rotates to the right a bit on its own. Also it glitches into another rigidbody. Any fix you know for that? Thanks a bunch!

nicedude80 · Mar 26, 2014 at 05:37 PM 0

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Nvm, i fixed the glitching part, but how would i make it so that it doesnt drift? Is there an easy way to do that? Like transferring that AddForce to go to the different "forward" so it doesnt drift?

moxiewhimsy · Mar 26, 2014 at 07:35 PM 0

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Not sure. It might be drifting for a few reasons. Is your water technically a solid (colliding with the boat constantly), or does it have some sort of buoyancy physics? How much drag does the boat have? Etc. I don't know all the ins and outs.

Bunny83 · Mar 26, 2014 at 07:48 PM 0

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@nicedude80: By "drift" do you mean momentum when you change direction? In real-life we have something we call friction. In "fluids" which includes air you call it Drag. You can simulate drag by setting a drag value on your rigidbody. Keep in mind the higher the drag value the faster it will decelerate and the more force you need to make it move.

Make a object move forwards

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