Develop Reference

How can I make it so that obstacles spawn based on how far the player has moved?

I have a problem when spawning obstacles. My character is a rocket which accelerates indefinitely and if the obstacles spawn at a fixed rate, the rocket will surpass the rate of the obstacles spawning. I do not want to spawn many objects at once. The rocket moves diagonally so I made some piece of code which shows that if the rocket's x position is a multiple of five it would spawn an obstacle. However it never gets to a multiple of five because it's x position has decimals.
This is my code so far.
using System.Collections;
using System.Collections.Generic;
using System.Threading;
using UnityEngine;
public class TriangleSpawner : MonoBehaviour
{
public GameObject Triangles;
public float Spacing = 4f;
Vector2 location;
void Update()
{
location = new Vector2(transform.position.x, transform.position.y);
if (location.x % 5 == 0)
{
Spacing = Spacing + 6.5f;
GameObject newTriangle = Instantiate(Triangles);
newTriangle.transform.position = transform.position + new Vector3(Spacing, Random.Range(-4, 3), 0);
}
}
}
How can I change this code so it can spawn based on the rocket's position so it never gets too slow?

You can for example remember the last position when an object was spawned, then see on each frame whether or not the player has moved far enough from it to spawn another one.
Example:
private float lastSpawnX;
void Start()
{
lastSpawnX = transform.position.x;
}
void Update()
{
if (Mathf.Abs(transform.position.x - lastSpawnX) >= 5)
{
lastSpawnX = transform.position.x;
// Spawn here, do what you have to
}
}
You should also consider what you are planning to do when the game becomes too fast, i.e you move more than 5 units in one frame. Normally you would always want some upper limit on how fast it can be.

Creating Simple Endless Moving Platform with cubes

Trying to create simple endless moving platform with 3 cubes of scale 70 on z(Player will not move forward, will just move left/right). The RepositionPlatform script is attached to each platform/cube which is responsible for movement and checks the z position of each platform and if it is <= -100.0f, then position is changed to (0,0,200.0f).
Problem is sometimes there is a little gap between the platforms(cubes) or there is a little overlap which I don't want.
Platforms should be placed one after each other without any gap or overlap!!!
Can anyone help find the issue looking at the script or suggest any other better way ?
The script below is attached to 3 platform game objects!!!
public class RepositionPlatform : MonoBehaviour
{
private GameObject platformGO;
[SerializeField]
private float speed;
// Start is called before the first frame update
void Start()
{
platformGO = this.gameObject;
Debug.Log("In RepositionPlatform Start method - "+ platformGO.name);
}
// Update is called once per frame
void Update()
{
Debug.Log("In RepositionPlatform Update Method- " + platformGO.name);
platformGO.transform.Translate(Vector3.back * Time.deltaTime * speed);
Transform platformTransform = platformGO.transform;
if(platformTransform.position.z <= -100.0f)
{
platformTransform.position = new Vector3(0,0,200.0f);
}
}
}

Probably because speed is a floating point value. You should read up on them if you haven't already.
Long story short, you aren't accounting for how far below -100 the value might have gone, you're just resetting it.
If you translate it instead, you will preserve any extra distance beyond -100 that the transform might have gone.
Try this instead:
If (transform.position.z < -100){
transform.Translate(new Vector3(0,0,200));
}
Edit
Should be Z value, not X

Transforming positions and adding a constant z axis valueC#

I have just started working on another project where one of the game mechanics is the ability to relocate a drone to the position of your mouse cursor.
Here is my code below where I have several problems(will specify)
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class lightDrone : MonoBehaviour
{
Vector3 newPosition;
void Start()
{
newPosition = transform.position + (0,0,10); //***Problem A***
}
void Update()
{
if (Input.GetMouseButtonDown(0))
{
RaycastHit hit;
Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
if (Physics.Raycast(ray, out hit))
{
newPosition = hit.point;
transform.position = newPosition; // ***Problem B***
}
}
}
}
Problem A - I am trying to have the new position = wherever the cursorhas clicked + 10 on the y axis so the "Drone" is seemed to be flying and not in the ground. This isn't achieving anything and is just giving me compiling errors.
I want the exact position to be (cursor.x, (public int (y)), cursor.z) but I have a very vague idea to do it.
Problem B -
Currently when I click my mouse, the object moves to the cursor but it seems to be just teleporting instantly. I want it to move at a certain speed and I think I need a public float to do so and change transform.position to translate.position but this again doesn't work.
Thank you in advance for answering my questions, I am trying to learn these new mechanics and how to code them. :)

Problem A
If you want your new position to be where ever the cursor clicked + 10 on the y axis it makes no sense to put any of your code in Start(). That's for initialization only. It runs just once at the beginning of the scene. Just add the 10 to your newPosition in the Update() method.
Problem B
Setting transform.position to a certain value will make your transform instantly move to that position. If you want to do it over time you need to move your transform a few increments at a time. Since this introduces that "over time" element, you need to use a method that takes place over time, so you need coroutines, asyncs or you can use just the update method if you're a tiny bit crafty.
Also you need the ray to intersect and hit something. Like a flat plane, the ground, terrain, anything with a collider. If it doesn't hit anywhere then you won't have a new place to move to.
Code
using UnityEngine;
public class LightDrone : MonoBehaviour
{
public float speed = 60.0f;
// Our destination needs to be remembered outside a single iteration of
// Update. So we put it outside of the method in order to remember it
// across multiple frames.
private Vector3 currentDestination;
// We need to check if we're at the destination yet so we know when to stop.
private bool notAtDestinationYet;
// When we're closer to the destination than this tolerance, we decide that
// we have arrived there.
private float tolerance = 0.1f;
private void Update()
{
if (Input.GetMouseButtonDown(0))
{
RaycastHit hit;
Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
if (Physics.Raycast(ray, out hit))
{
var newPosition = hit.point;
// You can add whatever height you want here. I added
// just 2 instead of 10.
currentDestination = newPosition + new Vector3(0, 2.0f, 0);
notAtDestinationYet = true;
}
}
if (notAtDestinationYet)
{
// Use a bit of vector math to get the direction from our current
// position to the destination. The direction is a normalized Vector
// that we can just multiply with our speed to go in that direction
// at that specific speed!
var heading = currentDestination - transform.position;
var distance = heading.magnitude;
var direction = heading / distance;
// Check if we've arrived at our destination.
if (distance < tolerance)
{
notAtDestinationYet = false;
}
else
{
// If the remaining distance between us and the destination is
// smaller than our speed, then we'll go further than necessary!
// This is called overshoot. So we need to make our speed
// smaller than the remaining distance.
// We also multiply by deltaTime to account for the variable
// amount of time that has passed since the last Update() call.
// Without multiplying with the amount of time that has passed
// our object's speed will increase or decrease when the
// framerate changes! We really don't want that.
float currentSpeed = Mathf.Clamp(speed * Time.deltaTime,
Mathf.Epsilon, distance);
transform.position += direction * currentSpeed;
}
}
}
}

Computationally quickly project 3d object onto 2d plane and get surface area of that (for aerodynamic drag)?

I'm trying to simulate swimming in Unity (using c#) by actually having the movements of the object create drag forces which then propel the object through the liquid.
to do this, I'm using the formula
F = -½ * C * d * velocity squared * A
where C is a coefficient of drag, d is the density of liquid, and A is the object's surface area that faces the direction of motion. A is calculated by projecting the 3D object onto a 2D plane perpendicular to the velocity vector.
Here's an image explaining A:
https://www.real-world-physics-problems.com/images/drag_force_2.png
Now I suspect Unity has a built in way to do this type of projection (since it does that every time there's a camera in the scene).
My question is:
How do I do this? Searches have not helped me with this (unless you're trying to do it with a camera)
Is there a built in function in Unity?
Is this computationally expensive? I am going to be doing this individual for possibly thousands of objects at a time.
I DO NOT need it to be very accurate. I'm just trying to make it a bit realistic, so I want objects with much bigger A to have more drag than ones with much lower A. Slight differences are inconsequential. The objects themselves won't be super complex, but some may have very different areas depending on orientation. So like a cone, for example, could change quite a bit depending on which direction it's moving. I could approximate the A with a simple shape if needed like ellipsoid or rectangle.
If it is computationally expensive, I read a journal article that used a cool way to approximate it. He created a grid of points (which he called voxels) within the objects spaced evenly, which effectively split the object into equal-sized spheres (which always have a cross-sectional surface area of a circle (easy to calculate). Then he calculated the drag force on each of these spheres and added them up to find the total drag (see images).
Images from THESIS REPORT ON: Real-time Physics-based Animation of a
Humanoid Swimmer, Jurgis Pamerneckas, 2014
link https://dspace.library.uu.nl/bitstream/handle/1874/298577/JP-PhysBAnimHumanSwim.pdf?sequence=2
This successfully estimated drag for him. But I see one problem, that the "voxels" that are deep in object are still contributing to drag, where only the ones near the leading edge should be contributing.
So, I thought of a possibility where I could project just the voxel points onto the 2Dplane (perpendicular to velocity) and then find a bounding shape or something, and approximate it that way. I suspect projecting a few points would be faster than projecting a whole 3d object.
this raises a few more questions:
Does this seem like a better method?
How would I create voxels in Unity?
Is it computationally faster?
Any better ideas?
Another thought I had was to do raycasting of some sort, though I can't think of how to do that, perhaps a grid of raycasts parallel to the velocity vector? and just count how many hit to approximate area?
UPDATE
I managed to implement basic drag force by manually typing in the value for A, now I need to approximate A in some way. Even with manual typing, it works surprisingly well for very basic "swimmers". In the image below, the swimmer correctly spins to the right since his left arm is bigger (I gave it double the value for A).
UPDATE 2
Based on #Pierre's comments, I tried computing A for the overall shape using the object's vertices (and also by selecting a few points on the vertices), projecting them onto a plane, and calculating the overall area of the resulting polygon. However, This only calculated the overall drag force on the object. It didn't calculate any rotational drag caused by certain parts of the object moving faster than others. For example, think of a baseball bat swing, the farthest part of the bat will be creating more drag since it's swinging faster than the handle.
This made me go back to the "voxel" idea, since I could calculate local drag sampled at several parts of the object.
I'm playing around with this idea, estimating the voxel's surface area by a circle. But still having a few issues making this estimate relatively accurate. Despite it being inaccurate, this seems to work quite well.
First, I'm using recasts to determine if the voxel can "see" in the direction of the velocity to determine if it's on the leading face of the object. If so, then I take the voxel's local (circular) surface area, and multiplying this by the dot product of the circle's normal and the local velocity vector. This scales the area based on how much it's actually facing the direction of motion.
The inaccuracies so far are due to the circles not actually estimating the local surface area very well, especially for weirdly elongated objects. The further vertices are from each other then the worse the estimation becomes. Any help in this department would be appreciated.
Also, I need to optimize this computationally. Right now, doing it with every vertex is proving to be fairly expensive. I'll keep updating as I progress, and any input would be very helpful! I'll post some code soon once I get a bit farther.
UPDATE 3
I did a fairly accurate implementation using voxels which I manually placed on the surface of the object, and manually estimated the local A when facing that voxel. I then used the dot product to estimate how much of that Area was facing the direction of motion. This worked very well. But the problem then was that even voxels that weren't on the leading edge of the object were contributing to drag. So I used Physics.Raycasts to pop a small distance away from the voxel in the direction of velocity, and then raycast back at the voxel. If this raycast hit the collider of the actual object (not the voxel) it meant it was on the leading edge. This worked fantastically and yielded surprisingly accurate natural looking behaviour of drag. Strangely shaped objects would eventually rotate to minimize drag just like you'd expect. However, as soon as I increased the resolution of voxels and/or added a few more objects into the scene, my frame rate dropped to nearly 3fps. The profiler showed that the brunt of the calculations were due to the raycasting step. I've tried to think of other ways to determine if the voxels are on the leading edge, so far to no avail.
So TLDR, I simulated drag really well, but not in a computationally fast manner.

I never figured out a way to speed up the calculations, but the simulation works great as long as the voxel count is low.
The simulation calculates drag based on the velocity of each voxel. It checks whether it's on the leading edge of the object, and if so applies its drag force.
The code is probably a bit difficult to follow but should at least get you started if you want to try it out. Let me know if you have any questions or need clarifications.
This code is a slightly cleaned up version from my Update#3 above.
In action:
At start of simulation (object moving in straight line towards bottom right of screen)
you can see the force arrows added for visualization and the circles representing the voxels. The force is correctly proportional to the surface area the voxels roughly represent. and only leading edges of the shapes are contributing drag
As the simulation continues, the shape correctly rotates into the most aerodynamic position because of the drag, and the rear sections stop contributing drag.
Drag Enabled Shape Class
this is dragged on main objet (rigidbody) to enable drag. You can either have it create voxels in a spread around a sphere shape. Or load in your own custom Voxels which are game objects with the Voxel Script attached, and are children of this object.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Linq;
[RequireComponent (typeof(Rigidbody))]
public class DragEnabledShape : MonoBehaviour {
const float EPSILON = 0.0001f;
public Voxel voxelPrefab;
public float C = 1f;
public float d = 0.5f;
public int resolutionFactor = 2;
public float maxDistanceFromCenter = 10f;
public bool displayDragVisualization = false;
public float forceVisualizationMultiplier = 1f;
public bool displayVoxels = false;
public bool loadCustomVoxels = false;
List<Voxel> voxels;
Rigidbody rb;
// Use this for initialization
void Awake () {
voxels = new List<Voxel> ();
rb = GetComponent<Rigidbody> ();
}
void OnEnable () {
if (loadCustomVoxels) {
var customVoxels = GetComponentsInChildren<Voxel> ();
voxels.AddRange (customVoxels);
if (displayDragVisualization) {
foreach (Voxel voxel in customVoxels) {
voxel.DisplayDrag (forceVisualizationMultiplier);
}
}
if (displayVoxels) {
foreach (Voxel voxel in customVoxels) {
voxel.Display ();
}
}
}
else {
foreach (Transform child in GetComponentsInChildren<Transform> ()) {
if (child.GetComponent<Collider> ()) {
//print ("creating voxels of " + child.gameObject.name);
CreateSurfaceVoxels (child);
}
}
}
}
void CreateSurfaceVoxels (Transform body) {
List<Vector3> directionList = new List<Vector3> ();
for (float i = -1; i <= 1 + EPSILON; i += 2f / resolutionFactor) {
for (float j = -1; j <= 1 + EPSILON; j += 2f / resolutionFactor) {
for (float k = -1; k <= 1 + EPSILON; k += 2f / resolutionFactor) {
Vector3 v = new Vector3 (i, j, k);
directionList.Add (v);
}
}
}
//float runningTotalVoxelArea = 0;
foreach (Vector3 direction in directionList) {
Ray upRay = new Ray (body.position, direction).Reverse (maxDistanceFromCenter);
RaycastHit[] hits = Physics.RaycastAll (upRay, maxDistanceFromCenter);
if (hits.Length > 0) {
//print ("Aiming for " + body.gameObject.name + "and hit count: " + hits.Length);
foreach (RaycastHit hit in hits) {
if (hit.collider == body.GetComponent<Collider> ()) {
//if (GetComponentsInParent<Transform> ().Contains (hit.transform)) {
//print ("hit " + body.gameObject.name);
GameObject empty = new GameObject ();
empty.name = "Voxels";
empty.transform.parent = body;
empty.transform.localPosition = Vector3.zero;
GameObject newVoxelObject = Instantiate (voxelPrefab.gameObject, empty.transform);
Voxel newVoxel = newVoxelObject.GetComponent<Voxel> ();
voxels.Add (newVoxel);
newVoxel.transform.position = hit.point;
newVoxel.transform.rotation = Quaternion.LookRotation (hit.normal);
newVoxel.DetermineTotalSurfaceArea (hit.distance - maxDistanceFromCenter, resolutionFactor);
newVoxel.attachedToCollider = body.GetComponent<Collider> ();
if (displayDragVisualization) {
newVoxel.DisplayDrag (forceVisualizationMultiplier);
}
if (displayVoxels) {
newVoxel.Display ();
}
//runningTotalVoxelArea += vox.TotalSurfaceArea;
//newVoxel.GetComponent<FixedJoint> ().connectedBody = shape.GetComponent<Rigidbody> ();
}
else {
//print ("missed " + body.gameObject.name + "but hit " + hit.transform.gameObject.name);
}
}
}
}
}
void FixedUpdate () {
foreach (Voxel voxel in voxels) {
rb.AddForceAtPosition (voxel.GetDrag (), voxel.transform.position);
}
}
}
Voxel class
This script is attached to small gameObjects placed around a shape. They represent the locations at which drag is computed. SO for complex shapes these should be at any extremities, and should be fairly spread out over the object. The voxel object's rigid body's mass should approximate the portion of the object this voxel represents.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Voxel : MonoBehaviour {
Vector3 velocity;
public Collider attachedToCollider;
Vector3 drag;
public Vector3 Drag {
get {
return drag;
}
}
float dragMagnitude;
public float DragMagnitude {
get {
return dragMagnitude;
}
}
bool leadingEdge;
public bool LeadingEdge {
get {
return leadingEdge;
}
}
bool firstUpdate = true;
public float localSurfaceArea;
Vector3 prevPos;
public VoxelForceVisualizer forceVisualizer;
public VoxelVisualizer voxelVisualizer;
const float AREA_COEFFICIENT = 1.1f;
const float EPSILON = 0.001f;
const float FAR_DISTANCE = 5f;
const float MAX_FORCE = 100f;
public void DetermineTotalSurfaceArea (float distanceFromCenter, float resolution) {
float theta = (Mathf.PI / 4) / resolution;
float localR = distanceFromCenter * Mathf.Tan (theta) * AREA_COEFFICIENT;// * (resolution / 0.01f);
localSurfaceArea = Mathf.PI * localR * localR;
}
bool IsVisibleFromPlane () {
if (attachedToCollider == null) {
throw new MissingReferenceException ("attached to collider not set");
}
bool visibleFromPlane = false;
//checks if this is leading edge of this part of object.
Ray justOutsideSurface = new Ray (this.transform.position, velocity).Reverse (EPSILON);
RaycastHit hit;
if (Physics.Raycast (justOutsideSurface, out hit, EPSILON * 2f)) {
if (hit.collider == attachedToCollider) {
//checks if other parts of this object are in front, blocking airflow.
//Ray wayOutsideSurface = new Ray (this.transform.position, velocity).Reverse (FAR_DISTANCE);
//RaycastHit firstHit;
//if (Physics.Raycast (wayOutsideSurface, out firstHit, FAR_DISTANCE * 2f)) {
//if (firstHit.collider == attachedToCollider) {
visibleFromPlane = true;
//}
//}
}
}
//}
leadingEdge = visibleFromPlane;
return visibleFromPlane;
}
void FixedUpdate () {
if (firstUpdate) {
prevPos = transform.position;
firstUpdate = false;
}
velocity = (transform.position - prevPos) / Time.deltaTime;
prevPos = transform.position;
}
public Vector3 GetDrag () {
if (IsVisibleFromPlane ()) {
float alignment = Vector3.Dot (velocity, this.transform.forward);
float A = alignment * localSurfaceArea;
dragMagnitude = DragForce.Calculate (velocity.sqrMagnitude, A);
//This clamp is necessary for imperfections in velocity calculation, especially with joint limits!
//dragMagnitude = Mathf.Clamp (dragMagnitude, 0f, MAX_FORCE);
drag = -velocity * dragMagnitude;
}
return drag;
}
public void Display () {
voxelVisualizer.gameObject.SetActive (true);
}
public void TurnOffDisplay () {
voxelVisualizer.gameObject.SetActive (false);
}
public void DisplayDrag (float forceMultiplier) {
forceVisualizer.gameObject.SetActive (true);
forceVisualizer.multiplier = forceMultiplier;
}
public void TurnOffDragDisplay () {
forceVisualizer.gameObject.SetActive (false);
}
}
VoxelForceVisualizer
This is a attached to prefab of a thin arrow that I put as a child of the voxels to allow force arrows to be drawn during debugging the drag force.
using UnityEngine;
public class VoxelForceVisualizer : MonoBehaviour {
const float TINY_NUMBER = 0.00000001f;
public Voxel voxel;
public float drag;
public float multiplier;
void Start () {
voxel = this.GetComponentInParent<Voxel> ();
}
// Update is called once per frame
void Update () {
Vector3 rescale;
if (voxel.LeadingEdge && voxel.Drag != Vector3.zero) {
this.transform.rotation = Quaternion.LookRotation (voxel.Drag);
rescale = new Vector3 (1f, 1f, voxel.DragMagnitude * multiplier);
}
else {
rescale = Vector3.zero;
}
this.transform.localScale = rescale;
drag = voxel.DragMagnitude;
}
}
VoxelVisualizer
this is attached to a small sphere object as a child of the voxel empty. It's just to see where the voxels are, and let the above scripts show/hide the voxels without disabling the drag force calculations.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class VoxelVisualizer : MonoBehaviour {
}
DragForce
This calculates the drag force
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public static class DragForce {
const float EPSILON = 0.000001f;
public static float Calculate (float coefficient, float density, float vsq, float A) {
float f = coefficient * density * vsq * A;
return f;
}
public static float Calculate (float vsq, float A) {
return Calculate (1f, 1f, vsq, A);
}
}

Calculate the displacement of device in unity

I'm making a 3D game in unity where the object should move forward and backward as the android device moves/accelerates in the Z axes. ie. When the player moves the devise in the direction of the +ve Z axis, the object should move forward, and when the player moves the devise in the direction of the -ve Z axis, the object should move backward.
This game is a multiplayer game, and the players will move in a large football field.
My idea to do this is using the accelerometer to calculate the acceleration of the device, then integrate the data of acceleration to get the device speed in the Z axis. and use the speed to move the device.
Using this equation
V2=V1 + ΔA . ΔT
Where
V2 : final velocity.
V1 : initial velocity.
ΔA : difference between the initial and final acceleration.
ΔT : difference between the initial and final time.
At first I tried to use kinematic equations to calculate the final speed, but I realized then that it can be only used when acceleration is constant. So a friend of me who studies physics differentiated this equation for me to use it when acceleration is variable.
I know that there will be some error in calculating the accurate displacement, and that the error will increase after the integration of acceleration, but this small percentage of error is okay for my application; I thought at first in using GPS instead of accelerometer but I found that GPS accuracy will be less than the sensors.
I know also that the error will be incredibly high after some time, so I reset the values of acceleration and velocity every 10 seconds. I'm also using a low-pass filter to reduce the noise of the sensor.
public class scriptMove : MonoBehaviour
{
const float kFilteringFactor = 0.1f;
public Vector3 A1;
public Vector3 A2;
public Vector3 A2ramping; // for the low-pass filter
public Vector3 V1;
public Vector3 V2;
public int SpeedFactor=1000; //this factor is for increasing acceleration to move in unity world
void resetAll()
{
Input.gyro.enabled = true;
A2 = Vector3.zero;
V1 = Vector3.zero;
V2 = Vector3.zero;
A2ramping = Vector3.zero;
}
// Use this for initialization
void Start()
{
InvokeRepeating("resetAll", 0, 10);
}
//http://stackoverflow.com/a/1736623
Vector3 ramping(Vector3 A)
{
A2ramping = A * kFilteringFactor + A2ramping * (1.0f - kFilteringFactor);
return A - A2ramping;
}
void getAcceleration(float deltaTime)
{
Input.gyro.enabled = true;
A1 = A2;
A2 = ramping(Input.gyro.userAcceleration) * SpeedFactor;
V2 = V1 + (A2 - A1) * deltaTime;
V1 = V2;
}
//Update is called once per frame
void Update()
{
getAcceleration(Time.deltaTime);
float distance = -1f;
Vector3 newPos = transform.position;
transform.Translate(Vector3.forward * Time.deltaTime * V2.z * distance);
}
}
The problem:
My code doesn't work always as expected when I move with the device;
Sometimes when I move forward (in the +ve Z axis of the device) the object moves forward also, but sometimes it doesn't move at all.
Sometimes when I'm still in my position the object moves alone by itself.
Sometimes when I move forward and suddenly stop, the object does not stop.
My questions:
Are those strange behaviors because of the accuracy of the device, or is there something I'm missing in my code.
If I'm missing something in my code, What is it?
I searched a lot about methods to get the most accurate position of the device, and I found that I can integrate GPS with accelerometer, how can I do this with my code in unity?

I don't know if you still need it but if anyone in the future need I will post what I found:
When I first used the Unity accelerometer I was thinking that the output was simply the device's rotation, and in a way is, but more than that it give us the acceleration but in order to have this value your must filter the gravity then you have the value.
I created a plugin for Android and get the Android's Accelerometer and Linear Accelerometer, the standard accelerometer give us a similar value of Unity accelerometer, the main difference is that is raw, and unity give us some refined output, for example if your game is Landscape unity automatically inverts X and Y axis, while the Android raw information don't. And the Linear accelerometer that is a fusion of sensors including the standard accelerometer, the output is acceleration without the gravity but the speed is terrible, while both (Unity and Android) accelerometer are updated every frame, the Linear accelerometer was updated every 4 to 5 frames what is a terrible rate for user's experience.
But going for Android plugin was great because it gave the light how to solve my problem of removing gravity from Unity Accelerometer, as you can find here:
https://developer.android.com/reference/android/hardware/SensorEvent.html
Under Sensor.TYPE_ACCELEROMETER
If we tilt the device, Unity Accelerometer gives you a value, for example 6, and while you hold in that position this is the value, is not a wave, if you tilt back really fast or really slowly it will give the value from 6 to 0 (supposing you move back to zero), what I wanted and accomplished with the code I'm sharing below is, when you turn it does a wave, returns the acceleration and back to zero, so is a acceleration deceleration curve, if you turn it really slow the acceleration returned is almost zero, if you turn it fast the response reflects this speed. If this is the result you are looking for you just need to create this class:
using UnityEngine;
public class AccelerometerUtil
{
public float alpha = 0.8f;
public float[] gravity = new float[3];
public AccelerometerUtil()
{
Debug.Log("AccelerometerUtil Init");
Vector3 currentAcc = Input.acceleration;
gravity[0] = currentAcc.x;
gravity[1] = currentAcc.y;
gravity[2] = currentAcc.z;
}
public Vector3 LowPassFiltered()
{
/*
https://developer.android.com/reference/android/hardware/SensorEvent.html
gravity[0] = alpha * gravity[0] + (1 - alpha) * event.values[0];
gravity[1] = alpha * gravity[1] + (1 - alpha) * event.values[1];
gravity[2] = alpha * gravity[2] + (1 - alpha) * event.values[2];
linear_acceleration[0] = event.values[0] - gravity[0];
linear_acceleration[1] = event.values[1] - gravity[1];
linear_acceleration[2] = event.values[2] - gravity[2];
*/
Vector3 currentAcc = Input.acceleration;
gravity[0] = alpha * gravity[0] + (1 - alpha) * currentAcc.x;
gravity[1] = alpha * gravity[1] + (1 - alpha) * currentAcc.y;
gravity[2] = alpha * gravity[2] + (1 - alpha) * currentAcc.z;
Vector3 linearAcceleration =
new Vector3(currentAcc.x - gravity[0],
currentAcc.y - gravity[1],
currentAcc.z - gravity[2]);
return linearAcceleration;
}
}
Once you have this class, just create it into your MonoBehaviour:
using UnityEngine;
public class PendulumAccelerometer : MonoBehaviour
{
private AccelerometerUtil accelerometerUtil;
// Use this for initialization
void Start()
{
accelerometerUtil = new AccelerometerUtil();
}
// Update is called once per frame
void Update()
{
Vector3 currentInput = accelerometerUtil.LowPassFiltered();
//TODO: Create your logic with currentInput (Linear Acceleration)
}
}
Notice that the TODO on MonoBehaviour is to be implemented, is up to you create an algorithm how to handle this values, in my case I found really useful to create a Graphic output and analise my acceleration before write it.
Really hope it helps

The movement is based on acceleration, so it will be dependant on how quickly you rotate your device. This is also why the object does not stop when you do. Suddenly stopping your device is a lot of acceleration, which then gets added to the amount the object is translating, which causes it to move a much greater distance than you intend.
I think what may be easier for you is to use the attitude of the gyro rather than the userAcceleration. The attitude returns a quaternion of the rotation of the device.
https://docs.unity3d.com/ScriptReference/Gyroscope-attitude.html
(You'll have to do a bit of experimenting, because I don't know what (0,0,0,0) on the attitude is. It could mean the device is flat on a table, or that it is sideways being held in front of you, or it could simply be the orientation of the device when the app first starts, I don't know how Unity initialises it.)
Once you have that Quaternion, you should be able to adjust velocity directly based off of how far in either direction the user is rotating the device. So if they rotate +ve Z-axis, you move forwards, if they move more, it moves faster, if they move -ve Z-axis, it slows down or moves backwards.
Regarding the GPS coordinates, you need to use LocationService for that.
http://docs.unity3d.com/ScriptReference/LocationService.html
You'll need to start LocationServices, wait for them to initialise (this bit is important), and then you can query the different parts using LocationService.lastData

I am trying to do the same thing as you. It is not trivial to get device's linear acceleration using just one sensor. You will need to implement a solution using both the accelerometer and the gyroscope (sensor fusion). Google has an android specific solution which behaves differently according to how sophisticated your device is. It uses multiple sensors as well as low/high pass filters (see Android TYPE_LINEAR_ACCELERATION sensor - what does it show?).
Google's Tango tablet should have sensors to address such issues.
If you want to get accelerometer data in Unity, try:
public class scriptMove : MonoBehaviour{
private float accelX;
private float accelY;
private float accelZ;
void Update(){
accelX = Input.acceleration.x;
accelY = Input.acceleration.y;
accelZ = Input.acceleration.z;
//pass values to your UI
}
}
What I am currently trying is to port Google's solution to Unity using IKVM.
This link might be helpful too:
Unity3D - Get smooth speed and acceleration with GPS data