Unity3D第三人称视角DEMO（相机跟随）

Third Person User Control

Introduction

在游戏开发中，角色控制模块是必不可少的。经典的第三人称视角就是被广泛应用的一项设计。这个Demo主要是针对Unity3D下第三人称视角模型（相机跟随）的一个简单实现，记录一下实现的过程与核心代码。

Idea

• 在Unity3D中导入一个人物模型，并创建一个可供人物活动的Terrain
• 调整摄像机至正确的视角（初始处于人物背后）
• 设置InputManager按键传值等基本属性，如W、A、S、D、Jump、Crouch等基本动作
• 导入或创建人物动作动画，并设定相应的Animator
• 编写脚本响应按键，实现的主要思路就是当人物移动时获取人物当前的朝向向量，归一化后乘速度得到人物前进的Vector3，之后再根据设定的转向速度将摄像机向量绕人物进行旋转（Z不变），并将人物朝向向量进行旋转得到转向向量，将转向向量与前进向量相加，即得到这一帧人物的移动向量，根据移动向量进行人物与摄像机的Transform即可。
• 在移动时绑定人物动画

Code

// Controll.cs
using System;
using UnityEngine;
using UnityStandardAssets.CrossPlatformInput;

namespace UnityStandardAssets.Characters.ThirdPerson
{
    [RequireComponent(typeof (ThirdPersonCharacter))]
    public class ThirdPersonUserControl : MonoBehaviour
    {
        private ThirdPersonCharacter m_Character; // A reference to the ThirdPersonCharacter on the object
        private Transform m_Cam;                  // A reference to the main camera in the scenes transform
        private Vector3 m_CamForward;             // The current forward direction of the camera
        private Vector3 m_Move;
        private bool m_Jump;                      // the world-relative desired move direction, calculated from the camForward and user input.


        private void Start()
        {
            if (Camera.main != null)
            {
                m_Cam = Camera.main.transform;
            }
            else
            {
                Debug.LogWarning(
                    "Warning: no main camera found. Third person character needs a Camera tagged \"MainCamera\", for camera-relative controls.", gameObject);
            }

            // get the third person character ( this should never be null due to require component )
            m_Character = GetComponent<ThirdPersonCharacter>();
        }


        private void Update()
        {
            if (!m_Jump)
            {
                m_Jump = CrossPlatformInputManager.GetButtonDown("Jump");
            }
        }


        private void FixedUpdate()
        {
            float h = CrossPlatformInputManager.GetAxis("Horizontal");
            float v = CrossPlatformInputManager.GetAxis("Vertical");
            bool crouch = Input.GetKey(KeyCode.C);
            if (Input.GetMouseButton (1)) 
            {
                h = Input.GetAxis ("Mouse X");
            }
            //Debug.Log ("h: " + h.ToString ("f4"));
            //Debug.Log ("s: " + v.ToString ("f4"));

            if (m_Cam != null)
            {
                m_CamForward = Vector3.Scale(m_Cam.forward, new Vector3(1, 0, 1)).normalized;
                m_Move = v*m_CamForward + h*m_Cam.right;
            }
            else
            {
                m_Move = v*Vector3.forward + h*Vector3.right;
            }
            if (Input.GetKey(KeyCode.LeftShift)) m_Move *= 0.5f;

            m_Character.Move(m_Move, crouch, m_Jump);
            m_Jump = false;
        }
    }
}

// Character.cs
using UnityEngine;

namespace UnityStandardAssets.Characters.ThirdPerson
{
    [RequireComponent(typeof(Rigidbody))]
    [RequireComponent(typeof(CapsuleCollider))]
    [RequireComponent(typeof(Animator))]
    public class ThirdPersonCharacter : MonoBehaviour
    {
        [SerializeField] float m_MovingTurnSpeed = 360;
        [SerializeField] float m_StationaryTurnSpeed = 180;
        [SerializeField] float m_JumpPower = 12f;
        [Range(1f, 4f)][SerializeField] float m_GravityMultiplier = 2f;
        [SerializeField] float m_RunCycleLegOffset = 0.2f; //specific to the character in sample assets, will need to be modified to work with others
        [SerializeField] float m_MoveSpeedMultiplier = 1f;
        [SerializeField] float m_AnimSpeedMultiplier = 1f;
        [SerializeField] float m_GroundCheckDistance = 0.1f;

        Rigidbody m_Rigidbody;
        Animator m_Animator;
        bool m_IsGrounded;
        float m_OrigGroundCheckDistance;
        const float k_Half = 0.5f;
        float m_TurnAmount;
        float m_ForwardAmount;
        Vector3 m_GroundNormal;
        float m_CapsuleHeight;
        Vector3 m_CapsuleCenter;
        CapsuleCollider m_Capsule;
        bool m_Crouching;


        void Start()
        {
            m_Animator = GetComponent<Animator>();
            m_Rigidbody = GetComponent<Rigidbody>();
            m_Capsule = GetComponent<CapsuleCollider>();
            m_CapsuleHeight = m_Capsule.height;
            m_CapsuleCenter = m_Capsule.center;

            m_Rigidbody.constraints = RigidbodyConstraints.FreezeRotationX | RigidbodyConstraints.FreezeRotationY | RigidbodyConstraints.FreezeRotationZ;
            m_OrigGroundCheckDistance = m_GroundCheckDistance;
        }


        public void Move(Vector3 move, bool crouch, bool jump)
        {
            if (move.magnitude > 1f) move.Normalize();
            move = transform.InverseTransformDirection(move);
            CheckGroundStatus();
            move = Vector3.ProjectOnPlane(move, m_GroundNormal);
            m_TurnAmount = Mathf.Atan2(move.x, move.z);
            m_ForwardAmount = move.z;

            ApplyExtraTurnRotation();

            if (m_IsGrounded)
            {
                HandleGroundedMovement(crouch, jump);
            }
            else
            {
                HandleAirborneMovement();
            }

            ScaleCapsuleForCrouching(crouch);
            PreventStandingInLowHeadroom();

        }


        void ScaleCapsuleForCrouching(bool crouch)
        {
            if (m_IsGrounded && crouch)
            {
                if (m_Crouching) return;
                m_Capsule.height = m_Capsule.height / 2f;
                m_Capsule.center = m_Capsule.center / 2f;
                m_Crouching = true;
            }
            else
            {
                Ray crouchRay = new Ray(m_Rigidbody.position + Vector3.up * m_Capsule.radius * k_Half, Vector3.up);
                float crouchRayLength = m_CapsuleHeight - m_Capsule.radius * k_Half;
                if (Physics.SphereCast(crouchRay, m_Capsule.radius * k_Half, crouchRayLength, Physics.AllLayers, QueryTriggerInteraction.Ignore))
                {
                    m_Crouching = true;
                    return;
                }
                m_Capsule.height = m_CapsuleHeight;
                m_Capsule.center = m_CapsuleCenter;
                m_Crouching = false;
            }
        }

        void PreventStandingInLowHeadroom()
        {
            if (!m_Crouching)
            {
                Ray crouchRay = new Ray(m_Rigidbody.position + Vector3.up * m_Capsule.radius * k_Half, Vector3.up);
                float crouchRayLength = m_CapsuleHeight - m_Capsule.radius * k_Half;
                if (Physics.SphereCast(crouchRay, m_Capsule.radius * k_Half, crouchRayLength, Physics.AllLayers, QueryTriggerInteraction.Ignore))
                {
                    m_Crouching = true;
                }
            }
        }


        void UpdateAnimator(Vector3 move)
        {
            m_Animator.SetFloat("Forward", m_ForwardAmount, 0.1f, Time.deltaTime);
            m_Animator.SetFloat("Turn", m_TurnAmount, 0.1f, Time.deltaTime);
            m_Animator.SetBool("Crouch", m_Crouching);
            m_Animator.SetBool("OnGround", m_IsGrounded);
            if (!m_IsGrounded)
            {
                m_Animator.SetFloat("Jump", m_Rigidbody.velocity.y);
            }

            float runCycle =
                Mathf.Repeat(
                    m_Animator.GetCurrentAnimatorStateInfo(0).normalizedTime + m_RunCycleLegOffset, 1);
            float jumpLeg = (runCycle < k_Half ? 1 : -1) * m_ForwardAmount;
            if (m_IsGrounded)
            {
                m_Animator.SetFloat("JumpLeg", jumpLeg);
            }

            if (m_IsGrounded && move.magnitude > 0)
            {
                m_Animator.speed = m_AnimSpeedMultiplier;
            }
            else
            {
                m_Animator.speed = 1;
            }
        }


        void HandleAirborneMovement()
        {
            Vector3 extraGravityForce = (Physics.gravity * m_GravityMultiplier) - Physics.gravity;
            m_Rigidbody.AddForce(extraGravityForce);

            m_GroundCheckDistance = m_Rigidbody.velocity.y < 0 ? m_OrigGroundCheckDistance : 0.01f;
        }


        void HandleGroundedMovement(bool crouch, bool jump)
        {
            if (jump && !crouch && m_Animator.GetCurrentAnimatorStateInfo(0).IsName("Grounded"))
            {
                m_Rigidbody.velocity = new Vector3(m_Rigidbody.velocity.x, m_JumpPower, m_Rigidbody.velocity.z);
                m_IsGrounded = false;
                m_Animator.applyRootMotion = false;
                m_GroundCheckDistance = 0.1f;
            }
        }

        void ApplyExtraTurnRotation()
        {
            float turnSpeed = Mathf.Lerp(m_StationaryTurnSpeed, m_MovingTurnSpeed, m_ForwardAmount);
            transform.Rotate(0, m_TurnAmount * turnSpeed * Time.deltaTime, 0);
        }


        public void OnAnimatorMove()
        {
            if ( m_IsGrounded && Time.deltaTime > 0)
            {
                Vector3 v = (m_Animator.deltaPosition * m_MoveSpeedMultiplier) / Time.deltaTime;
                m_Rigidbody.velocity = v;
            }
        }


        void CheckGroundStatus()
        {
            RaycastHit hitInfo;
#if UNITY_EDITOR
            Debug.DrawLine(transform.position + (Vector3.up * 0.1f), transform.position + (Vector3.up * 0.1f) + (Vector3.down * m_GroundCheckDistance));
#endif
            if (Physics.Raycast(transform.position + (Vector3.up * 0.1f), Vector3.down, out hitInfo, m_GroundCheckDistance))
            {
                m_GroundNormal = hitInfo.normal;
                m_IsGrounded = true;
                m_Animator.applyRootMotion = true;
            }
            else
            {
                m_IsGrounded = false;
                m_GroundNormal = Vector3.up;
                m_Animator.applyRootMotion = false;
            }
        }
    }
}

PS

这个DEMO实现了基本的行走、快跑、跳跃、蹲下、站立等基本动作，也可以自己扩展其他功能，如通过鼠标右键拖拽调整视角等，鼠标左键点击地面寻路等等，在后续学习中会不断加进去的！