Unity3D汽车物理引擎的安卓重力感应适配

////////////////2015/08/24///////////////////

///////////////by XBW///////////////////////

//////////////环境 unity4.6.1//////////////

试一下这个汽车的物理引擎的插件，在PC上测试完全没有问题，但是选择平台到安卓版的时候会出现一些问题，首先就是这个SmoothFollow.js脚本的问题，话说这是unity自带的脚本，是官方的脚本，不应该有问题，但是选择安卓平台出错了，是一些变量没有定义，不是没有定义吗，索性自己定义吧，修改后的SmoothFollow.js脚本如下

/*
This camera smoothes out rotation around the y-axis and height.
Horizontal Distance to the target is always fixed.

There are many different ways to smooth the rotation but doing it this way gives you a lot of control over how the camera behaves.

For every of those smoothed values we calculate the wanted value and the current value.
Then we smooth it using the Lerp function.
Then we apply the smoothed values to the transform's position.
*/

// The target we are following
var target : Transform;
// The distance in the x-z plane to the target
var distance = 10.0;
// the height we want the camera to be above the target
var height = 5.0;
// How much we 
var heightDamping = 2.0;
var rotationDamping = 3.0;
var wantedHeight : float;
var currentHeight : float;
var wantedRotationAngle : float;
var currentRotationAngle : float;
var currentRotation : Quaternion;

// Place the script in the Camera-Control group in the component menu
@script AddComponentMenu("Camera-Control/Smooth Follow")

function LateUpdate () {
	// Early out if we don't have a target
	if (!target)
		return;
	
	// Calculate the current rotation angles
	wantedRotationAngle = target.eulerAngles.y;
	wantedHeight = target.position.y + height;
		
	currentRotationAngle = transform.eulerAngles.y;
	currentHeight = transform.position.y;
	
	// Damp the rotation around the y-axis
	currentRotationAngle = Mathf.LerpAngle (currentRotationAngle, wantedRotationAngle, rotationDamping * Time.deltaTime);

	// Damp the height
	currentHeight = Mathf.Lerp (currentHeight, wantedHeight, heightDamping * Time.deltaTime);

	// Convert the angle into a rotation
	currentRotation = Quaternion.Euler (0, currentRotationAngle, 0);
	
	// Set the position of the camera on the x-z plane to:
	// distance meters behind the target
	transform.position = target.position;
	transform.position -= currentRotation * Vector3.forward * distance;

	// Set the height of the camera
	transform.position.y = currentHeight;
	
	// Always look at the target
	transform.LookAt (target);
}

这样就好了，但是仍然会有错误，是position不是object的成员，这个错误发生在AICar，就是这个汽车插件的智能脚本中，这样呢，具体原因我是真不清楚，索性就把一些代码注释了，这样经过测试也是没问题的，报错也没有了，看一下修改后的AICar脚本

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

// Here's the basic AI driven 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.

// These variables allow the script to power the wheels of the car.
var FrontLeftWheel : WheelCollider;
var FrontRightWheel : WheelCollider;
var BackLeftWheel : WheelCollider;
var BackRightWheel : 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.
var GearRatio : float[];
var DifferentialRatio : float = 3.1;
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.
var EngineTorque : float = 600.0;
var MaxEngineRPM : float = 3000.0;
var MinEngineRPM : float = 1000.0;
private var EngineRPM : float = 0.0;

// Here's all the variables for the AI, the waypoints are determined in the "GetWaypoints" function.
// the waypoint container is used to search for all the waypoints in the scene, and the current
// waypoint is used to determine which waypoint in the array the car is aiming for.
var waypointContainer : GameObject;
private var waypoints : Array;
private var currentWaypoint : int = 0;

// input steer and input torque are the values substituted out for the player input. The 
// "NavigateTowardsWaypoint" function determines values to use for these variables to move the car
// in the desired direction.
private var inputSteer : float = 0.0;
private var inputTorque : 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.
	rigidbody.centerOfMass.y = -.45;
	rigidbody.centerOfMass.z = -0.15;
	
	// Call the function to determine the array of waypoints. This sets up the array of points by finding
	// transform components inside of a source container.
	GetWaypoints();
}

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.
	rigidbody.drag = rigidbody.velocity.magnitude / 250;
	
	// Call the funtion to determine the desired input values for the car. This essentially steers and
	// applies gas to the engine.
	NavigateTowardsWaypoint();
	
	// Compute the engine RPM based on the average RPM of the two wheels, then call the shift gear function
	EngineRPM = (BackLeftWheel.rpm + BackRightWheel.rpm)/2 * GearRatio[CurrentGear]*DifferentialRatio;
	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.
	audio.pitch = Mathf.Abs(EngineRPM / MaxEngineRPM) + 0.5 ;
	// this line is just to ensure that the pitch does not reach a value higher than is desired.
	if ( audio.pitch > 1.5 ) {
		audio.pitch = 1.5;
	}
	
	// finally, apply the values to the wheels.	The torque applied is divided by the current gear, and
	// multiplied by the calculated AI input variable.
	//FrontLeftWheel.motorTorque = EngineTorque / GearRatio[CurrentGear]*DifferentialRatio * inputTorque;
	//FrontRightWheel.motorTorque = EngineTorque / GearRatio[CurrentGear]*DifferentialRatio * inputTorque;
	BackLeftWheel.motorTorque = -EngineTorque / GearRatio[CurrentGear]*DifferentialRatio * inputTorque;
	BackRightWheel.motorTorque = -EngineTorque / GearRatio[CurrentGear]*DifferentialRatio * inputTorque;
	
	// the steer angle is an arbitrary value multiplied by the calculated AI input.
	FrontLeftWheel.steerAngle = 35 * inputSteer;
	FrontRightWheel.steerAngle = 35 * inputSteer;
}

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.
	if ( EngineRPM >= MaxEngineRPM ) {
		var AppropriateGear : int = CurrentGear;
		
		for ( var i = 0; i < GearRatio.length; i ++ ) {
			if ( BackLeftWheel.rpm * GearRatio[i]*DifferentialRatio < MaxEngineRPM ) {
				AppropriateGear = i;
				break;
			}
		}
		
		CurrentGear = AppropriateGear;
	}
	
	if ( EngineRPM <= MinEngineRPM ) {
		AppropriateGear = CurrentGear;
		
		for ( var j = GearRatio.length-1; j >= 0; j -- ) {
			if ( BackLeftWheel.rpm * GearRatio[j]*DifferentialRatio > MinEngineRPM ) {
				AppropriateGear = j;
				break;
			}
		}
		
		CurrentGear = AppropriateGear;
	}
}

function GetWaypoints () {
	// Now, this function basically takes the container object for the waypoints, then finds all of the transforms in it,
	// once it has the transforms, it checks to make sure it's not the container, and adds them to the array of waypoints.
	var potentialWaypoints : Array = waypointContainer.GetComponentsInChildren( Transform );
	waypoints = new Array();
	
	for ( var potentialWaypoint : Transform in potentialWaypoints ) {
		if ( potentialWaypoint != waypointContainer.transform ) {
			waypoints[ waypoints.length ] = potentialWaypoint;
		}
	}
}

function NavigateTowardsWaypoint () {
	// now we just find the relative position of the waypoint from the car transform,
	// that way we can determine how far to the left and right the waypoint is.
	//var RelativeWaypointPosition : Vector3 = transform.InverseTransformPoint( Vector3( 
	//											waypoints[currentWaypoint].position.x, 
		//										transform.position.y, 
			//									waypoints[currentWaypoint].position.z ) );
																				
																				
	// by dividing the horizontal position by the magnitude, we get a decimal percentage of the turn angle that we can use to drive the wheels
	//inputSteer = RelativeWaypointPosition.x / RelativeWaypointPosition.magnitude;
	
	// now we do the same for torque, but make sure that it doesn't apply any engine torque when going around a sharp turn...
	//if ( Mathf.Abs( inputSteer ) < 1.0 ) {
		//inputTorque = RelativeWaypointPosition.z / RelativeWaypointPosition.magnitude - Mathf.Abs( inputSteer );
	//}else{
		//inputTorque = 0.0;
	//}
	
	// this just checks if the car's position is near enough to a waypoint to count as passing it, if it is, then change the target waypoint to the
	// next in the list.
	//if ( RelativeWaypointPosition.magnitude < 30 ) {
		//currentWaypoint ++;
		
		//if ( currentWaypoint >= waypoints.length ) {
			//currentWaypoint = 0;
		//}
	//}
	
}

这样就好了，安卓的平台的错误消失了，可以运行了，但是我们的目的是重力感应控制汽车的移动，这样呢，我们找到控制汽车移动的脚本PlayerCar脚本

我们把用PC方向键控制的部分改为重力感应的输入控制，

//BackLeftWheel.motorTorque = -EngineTorque * GearRatio[CurrentGear] * DifferentialRatio * Input.GetAxis("Vertical") *100;
		//BackRightWheel.motorTorque = -EngineTorque * GearRatio[CurrentGear] * DifferentialRatio * Input.GetAxis("Vertical") *100;
		BackLeftWheel.motorTorque = -EngineTorque * GearRatio[CurrentGear] * DifferentialRatio * Input.acceleration.y *100;
		BackRightWheel.motorTorque = -EngineTorque * GearRatio[CurrentGear] * DifferentialRatio * Input.acceleration.y *100;
	//}

	// the steer angle is an arbitrary value multiplied by the user input.
	//FrontLeftWheel.steerAngle = 35 * Input.GetAxis("Horizontal");
	//FrontRightWheel.steerAngle = 35 * Input.GetAxis("Horizontal");
	FrontLeftWheel.steerAngle = 35 * Input.acceleration.x;
	FrontRightWheel.steerAngle = 35 *Input.acceleration.x;

这样就好了，赶紧到安卓真机测试一下吧，是不是很好玩呢，对于那个注释掉的部分如果有明白的专家批评指正。

那个Car Phasic插件百度云链接在这

链接：http://pan.baidu.com/s/1jGEPwai 密码：9wnj