Unity3d 汽车物理系统

 1 // ----------- CAR TUTORIAL SAMPLE PROJECT, ? Andrew Gotow 2009 -----------------

// Here's the basic car script described in my tutorial at www.gotow.net/andrew/blog.
// A Complete explaination of how this script works can be found at the link above, along
// with detailed instructions on how to write one of your own, and tips on what values to
// assign to the script variables for it to work well for your application.

// Contact me at Maxwelldoggums@Gmail.com for more information.
//这些是外国人写的赛车例子，我个人认为非常好，是用JS写的！
//我来注解一下！
// These variables allow the script to power the wheels of the car.
//前左轮和前右轮
var FrontLeftWheel : WheelCollider;
var FrontRightWheel : WheelCollider;
// These variables are for the gears, the array is the list of ratios. The script
// uses the defined gear ratios to determine how much torque to apply to the wheels.
//齿轮转数系数
var GearRatio : float[];
//档位
var CurrentGear : int = 0;
// These variables are just for applying torque to the wheels and shifting gears.
// using the defined Max and Min Engine RPM, the script can determine what gear the
// car needs to be in.
//向前的动力
var EngineTorque : float = 600.0;
//引擎最大的转速
var MaxEngineRPM : float = 3000.0;
//引擎最小的转速
var MinEngineRPM : float = 1000.0;
private var EngineRPM : float = 0.0;
function Start () {
// I usually alter the center of mass to make the car more stable. I'ts less likely to flip this way.
//设置车的中心点，一般在车的底盘下，这样车行驶起来稳定，不会轻易翻车！
rigidbody.centerOfMass.y = -1.5;
}
function Update () {
// This is to limith the maximum speed of the car, adjusting the drag probably isn't the best way of doing it,
// but it's easy, and it doesn't interfere with the physics processing.
//设置车的阻力为 车的向前的速度的长度除以250
rigidbody.drag = rigidbody.velocity.magnitude / 250;
// Compute the engine RPM based on the average RPM of the two wheels, then call the shift gear function
//档位的转速值车
EngineRPM = (FrontLeftWheel.rpm + FrontRightWheel.rpm)/2 * GearRatio[CurrentGear];
ShiftGears();
// set the audio pitch to the percentage of RPM to the maximum RPM plus one, this makes the sound play
// up to twice it's pitch, where it will suddenly drop when it switches gears.
//音频源的音调 发动机的引擎转速越快，则音调越高！
audio.pitch = Mathf.Abs(EngineRPM / MaxEngineRPM) + 1.0 ;
// this line is just to ensure that the pitch does not reach a value higher than is desired.
//超过2.0则归位到2.0
if ( audio.pitch > 2.0 ) {
audio.pitch = 2.0;
}
// finally, apply the values to the wheels.    The torque applied is divided by the current gear, and
// multiplied by the user input variable.
//前面的两个轮子的力矩
FrontLeftWheel.motorTorque = EngineTorque / GearRatio[CurrentGear] * Input.GetAxis("Vertical");
FrontRightWheel.motorTorque = EngineTorque / GearRatio[CurrentGear] * Input.GetAxis("Vertical");
Debug.Log(Input.GetAxis("Vertical"));
// the steer angle is an arbitrary value multiplied by the user input.
FrontLeftWheel.steerAngle = 10 * Input.GetAxis("Horizontal");
FrontRightWheel.steerAngle = 10 * Input.GetAxis("Horizontal");
}
//换档位
function ShiftGears() {
// this funciton shifts the gears of the vehcile, it loops through all the gears, checking which will make
// the engine RPM fall within the desired range. The gear is then set to this "appropriate" value.
//如果当前引擎的值大于最大引擎
if ( EngineRPM >= MaxEngineRPM ) {
var AppropriateGear : int = CurrentGear;
//则从0开始，往上查，如果左轮的rpm乘以齿轮数小于
for ( var i = 0; i < GearRatio.length; i ++ ) {
if ( FrontLeftWheel.rpm * GearRatio[i] < MaxEngineRPM ) {
AppropriateGear = i;
break;
}
}

CurrentGear = AppropriateGear;
}

if ( EngineRPM <= MinEngineRPM ) {
AppropriateGear = CurrentGear;

for ( var j = GearRatio.length-1; j >= 0; j -- ) {
if ( FrontLeftWheel.rpm * GearRatio[j] > MinEngineRPM ) {
AppropriateGear = j;
break;
}
}

CurrentGear = AppropriateGear;
}
}