"CarTutorial" of Unity 3d

[fvasc9]

Hi guys,

I already post this, but with little changes.

How to put brake and backward lights in “AlternatePhysicsModel”?

And how to put a speedometer with pointer with the same “AlternatePhysicsModel”?

[slkjdfv]

just turn the lights on when you press the brake key and if the cars velocity is negative turn the reverse lights on. At least thats my understanding on how to do it. You could also try changing the lights material to a self-illuminated material. Theres tutorials all over the place about speedometers try searching google.

[fvasc9]

Yes I now there are tutorial about the speedometer but not for C# Script…

By the way, this is the script I use in the car: (Drivetrain)

using UnityEngine;
using System.Collections;

// This class simulates a car’s engine and drivetrain, generating
// torque, and applying the torque to the wheels.
public class Drivetrain : MonoBehaviour {

// All the wheels the drivetrain should power
public Wheel[ ] poweredWheels;

// The gear ratios, including neutral (0) and reverse (negative) gears
public float[ ] gearRatios;

// The final drive ratio, which is multiplied to each gear ratio
public float finalDriveRatio = 3.23f;

// The engine’s torque curve characteristics. Since actual curves are often hard to come by,
// we approximate the torque curve from these values instead.

// powerband RPM range
public float minRPM = 800;
public float maxRPM = 6400;

// engine’s maximal torque (in Nm) and RPM.
public float maxTorque = 664;
public float torqueRPM = 4000;

// engine’s maximal power (in Watts) and RPM.
public float maxPower = 317000;
public float powerRPM = 5000;

// engine inertia (how fast the engine spins up), in kg * m^2
public float engineInertia = 0.3f;

// engine’s friction coefficients - these cause the engine to slow down, and cause engine braking.

// constant friction coefficient
public float engineBaseFriction = 25f;
// linear friction coefficient (higher friction when engine spins higher)
public float engineRPMFriction = 0.02f;

// Engine orientation (typically either Vector3.forward or Vector3.right).
// This determines how the car body moves as the engine revs up.
public Vector3 engineOrientation = Vector3.forward;

// Coefficient determining how muchg torque is transfered between the wheels when they move at
// different speeds, to simulate differential locking.
public float differentialLockCoefficient = 0;

// inputs
// engine throttle
public float throttle = 0;
// engine throttle without traction control (used for automatic gear shifting)
public float throttleInput = 0;

// shift gears automatically?
public bool automatic = true;

// state
public int gear = 2;
public float rpm;
public float slipRatio = 0.0f;
float engineAngularVelo;

float Sqr (float x) { return x*x; }

// Calculate engine torque for current rpm and throttle values.
float CalcEngineTorque ()
{
float result;
if(rpm < torqueRPM)
result = maxTorque*(-Sqr(rpm / torqueRPM - 1) + 1);
else {
float maxPowerTorque = maxPower/(powerRPM2Mathf.PI/60);
float aproxFactor = (maxTorque-maxPowerTorque)/(2torqueRPMpowerRPM-Sqr(powerRPM)-Sqr(torqueRPM));
float torque = aproxFactor * Sqr(rpm-torqueRPM)+maxTorque;
result=torque>0?torque:0;
}
if(rpm > maxRPM)
{
result *= 1-((rpm-maxRPM) * 0.006f);
if(result<0)
result=0;
}
if(rpm<0)
result=0;
return result;
}

void FixedUpdate ()
{
float ratio = gearRatios[gear] * finalDriveRatio;
float inertia = engineInertia * Sqr(ratio);
float engineFrictionTorque = engineBaseFriction + rpm * engineRPMFriction;
float engineTorque = (CalcEngineTorque() + Mathf.Abs(engineFrictionTorque)) * throttle;
slipRatio = 0.0f;

if (ratio == 0)
{
// Neutral gear - just rev up engine
float engineAngularAcceleration = (engineTorque-engineFrictionTorque) / engineInertia;
engineAngularVelo += engineAngularAcceleration * Time.deltaTime;

// Apply torque to car body
rigidbody.AddTorque(-engineOrientation * engineTorque);
}
else
{
float drivetrainFraction = 1.0f/poweredWheels.Length;
float averageAngularVelo = 0;
foreach(Wheel w in poweredWheels)
averageAngularVelo += w.angularVelocity * drivetrainFraction;

// Apply torque to wheels
foreach(Wheel w in poweredWheels)
{
float lockingTorque = (averageAngularVelo - w.angularVelocity) * differentialLockCoefficient;
w.drivetrainInertia = inertia * drivetrainFraction;
w.driveFrictionTorque = engineFrictionTorque * Mathf.Abs(ratio) * drivetrainFraction;
w.driveTorque = engineTorque * ratio * drivetrainFraction + lockingTorque;

slipRatio += w.slipRatio * drivetrainFraction;
}

// update engine angular velo
engineAngularVelo = averageAngularVelo * ratio;
}

// update state
slipRatio = Mathf.Sign ( ratio );
rpm = engineAngularVelo * (60.0f/(2Mathf.PI));

// very simple simulation of clutch - just pretend we are at a higher rpm.
float minClutchRPM = minRPM;
if (gear == 2)
minClutchRPM += throttle * 3000;
if (rpm < minClutchRPM)
rpm = minClutchRPM;

// Automatic gear shifting. Bases shift points on throttle input and rpm.
if (automatic)
{
if (rpm >= maxRPM * (0.5f + 0.5f * throttleInput))
ShiftUp ();
else if (rpm <= maxRPM * (0.25f + 0.4f * throttleInput) gear > 2)
ShiftDown ();
if (throttleInput < 0 rpm <= minRPM)
gear = (gear == 0?2:0);
}
}

public void ShiftUp () {
if (gear < gearRatios.Length - 1)
gear ++;
}

public void ShiftDown () {
if (gear > 0)
gear --;
}
}

From here where i put the brake lights and backward lights?

[slkjdfv]

look for the script where Input is taken for the brake lights. As for the reversing lights make a new function and check if the gear is below zero and if it is turn the reverse lights on so it should look kinda like this (and remember to make a new variable thats a light container at the begining of the script to store your reverse lights) -

//This next line should go near the top of the script where variables are set up
public Light[] ReverseLights = new Light[2];

void Update()
{
    if (gear < 0)
    {
         //Turn the reversing lights on
         for (int i = 0; i < ReverseLights.Length; i++)
         {
              ReverseLights[i].enabled = true;
         }
    }
}

and just put an else case to turn them off. hope this helps

[fvasc9]

Tnks for help me, I’m trying the script…

By the way, do you know the “Car Tutorial” AlternatePhysicsModel?

[slkjdfv]

I’m using it for my current game. I don’t know every thing about it. For me I’m learning as I use it and I’m modifying the code so I can enable and disable the car when I want. And your welcome :).