unity自带脚本ThirdPersonCamera.cs（收藏）

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using UnityEngine;

using System.Collections;

/**

* @Author : www.xuanyusong.com

*/

public class ThirdPersonCamera : MonoBehaviour {

public Transform cameraTransform;

private Transform _target;

public static float distance = 10.0f;

public float height = 1.0f;

public float angularSmoothLag = 0.3f;

public float angularMaxSpeed = 15.0f;

public float heightSmoothLag = 0.3f;

public float snapSmoothLag = 0.2f;

public float snapMaxSpeed = 720.0f;

public float clampHeadPositionScreenSpace = 0.75f;

public float lockCameraTimeout = 0.2f;

private Vector3 headOffset = Vector3.zero;

private Vector3 centerOffset = Vector3.zero;

private float heightVelocity = 0.0f;

private float angleVelocity = 0.0f;

private bool snap = false;

private ThirdPersonController controller;

private float targetHeight = 100000.0f;

void Awake ()

{

if(!cameraTransform && Camera.main)

cameraTransform = Camera.main.transform;

if(!cameraTransform) {

Debug.Log(“Please assign a camera to the ThirdPersonCamera script.”);

enabled = false;

}

_target = transform;
if (_target)
{
controller = _target.GetComponent<ThirdPersonController>();
}

if (controller)
{
CharacterController characterController  = (CharacterController)_target.collider;
centerOffset = characterController.bounds.center - _target.position;
headOffset = centerOffset;
headOffset.y = characterController.bounds.max.y - _target.position.y;
}
else
Debug.Log("Please assign a target to the camera that has a ThirdPersonController script attached.");

Cut(_target, centerOffset);

}

void DebugDrawStuff ()

{

Debug.DrawLine(_target.position, _target.position + headOffset);

}

float AngleDistance (float a , float b )

{

a = Mathf.Repeat(a, 360);

b = Mathf.Repeat(b, 360);

return Mathf.Abs(b - a);

}

void Apply (Transform dummyTarget, Vector3 dummyCenter)

{

// Early out if we don’t have a target

if (!controller)

return;

Vector3 targetCenter = _target.position + centerOffset;
Vector3 targetHead = _target.position + headOffset;

// DebugDrawStuff();

// Calculate the current & target rotation angles
float originalTargetAngle = _target.eulerAngles.y;
float currentAngle = cameraTransform.eulerAngles.y;

// Adjust real target angle when camera is locked
float targetAngle = originalTargetAngle;

// When pressing Fire2 (alt) the camera will snap to the target direction real quick.
// It will stop snapping when it reaches the target
if (Input.GetButton("Fire2"))
snap = true;

if (snap)
{
// We are close to the target, so we can stop snapping now!
if (AngleDistance (currentAngle, originalTargetAngle) < 3.0)
snap = false;

currentAngle = Mathf.SmoothDampAngle(currentAngle, targetAngle, ref angleVelocity, snapSmoothLag, snapMaxSpeed);
}
// Normal camera motion
else
{
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if (controller.GetLockCameraTimer () < lockCameraTimeout)
{
targetAngle = currentAngle;
}

// Lock the camera when moving backwards!
// * It is really confusing to do 180 degree spins when turning around.
if (AngleDistance (currentAngle, targetAngle) > 160 && controller.IsMovingBackwards ())
targetAngle += 180;

currentAngle = Mathf.SmoothDampAngle(currentAngle, targetAngle, ref angleVelocity, angularSmoothLag, angularMaxSpeed);
}

// When jumping don't move camera upwards but only down!
if (controller.IsJumping ())
{
// We'd be moving the camera upwards, do that only if it's really high
float newTargetHeight = targetCenter.y + height;
if (newTargetHeight < targetHeight || newTargetHeight - targetHeight > 5)
targetHeight = targetCenter.y + height;
}
// When walking always update the target height
else
{
targetHeight = targetCenter.y + height;
}

// Damp the height
float currentHeight = cameraTransform.position.y;
currentHeight = Mathf.SmoothDamp (currentHeight, targetHeight, ref heightVelocity, heightSmoothLag);

// Convert the angle into a rotation, by which we then reposition the camera
Quaternion currentRotation = Quaternion.Euler (0, currentAngle, 0);

// Set the position of the camera on the x-z plane to:
// distance meters behind the target
cameraTransform.position = targetCenter;
cameraTransform.position += currentRotation * Vector3.back * distance;

// Set the height of the camera
cameraTransform.position = new Vector3(cameraTransform.position.x,currentHeight,cameraTransform.position.z);

// Always look at the target
SetUpRotation(targetCenter, targetHead);

}

void LateUpdate () {

Apply (transform, Vector3.zero);

}

void Cut (Transform dummyTarget , Vector3 dummyCenter)

{

float oldHeightSmooth = heightSmoothLag;

float oldSnapMaxSpeed = snapMaxSpeed;

float oldSnapSmooth = snapSmoothLag;

snapMaxSpeed = 10000;
snapSmoothLag = 0.001f;
heightSmoothLag = 0.001f;

snap = true;
Apply (transform, Vector3.zero);

heightSmoothLag = oldHeightSmooth;
snapMaxSpeed = oldSnapMaxSpeed;
snapSmoothLag = oldSnapSmooth;

}

void SetUpRotation (Vector3 centerPos,Vector3 headPos)

{

// Now it’s getting hairy. The devil is in the details here, the big issue is jumping of course.

// * When jumping up and down we don’t want to center the guy in screen space.

// This is important to give a feel for how high you jump and avoiding large camera movements.

//

// * At the same time we dont want him to ever go out of screen and we want all rotations to be totally smooth.

//

// So here is what we will do:

//

// 1. We first find the rotation around the y axis. Thus he is always centered on the y-axis

// 2. When grounded we make him be centered

// 3. When jumping we keep the camera rotation but rotate the camera to get him back into view if his head is above some threshold

// 4. When landing we smoothly interpolate towards centering him on screen

Vector3 cameraPos = cameraTransform.position;

Vector3 offsetToCenter = centerPos - cameraPos;

// Generate base rotation only around y-axis
Quaternion yRotation = Quaternion.LookRotation(new Vector3(offsetToCenter.x, 0, offsetToCenter.z));

Vector3 relativeOffset = Vector3.forward * distance + Vector3.down * height;
cameraTransform.rotation = yRotation * Quaternion.LookRotation(relativeOffset);

// Calculate the projected center position and top position in world space
Ray centerRay = cameraTransform.camera.ViewportPointToRay(new Vector3(0.5f, 0.5f, 1f));
Ray topRay = cameraTransform.camera.ViewportPointToRay(new Vector3(0.5f, clampHeadPositionScreenSpace, 1f));

Vector3 centerRayPos = centerRay.GetPoint(distance);
Vector3 topRayPos = topRay.GetPoint(distance);

float centerToTopAngle = Vector3.Angle(centerRay.direction, topRay.direction);

float heightToAngle = centerToTopAngle / (centerRayPos.y - topRayPos.y);

float extraLookAngle = heightToAngle * (centerRayPos.y - centerPos.y);
if (extraLookAngle < centerToTopAngle)
{
extraLookAngle = 0;
}

else
{
extraLookAngle = extraLookAngle - centerToTopAngle;
cameraTransform.rotation *= Quaternion.Euler(-extraLookAngle, 0, 0);
}

}

Vector3 GetCenterOffset ()
{
return centerOffset;
}

}