Basic Concepts

*** Screen point to Camera point

 * You need to interprete the screen coordinate to world coordinate

 * Camera has the ability to convert the screen coordinate to world coordinate

 Example:

  Camera cam;

  Vector3 pointInWorldCoordinate = cam.ScreenPointToRay(Vector3 point)

*** Character Controlling, Moving

 * care in mind that there are Local coordinate system and World coordinate system

 * if you want to go forward in local coordinate, you should convert it to world coordinate system

 * there are methods such as Transform.TransformDirection.

 ** refer to: World of Warcraft project

*** Navigation System

 * NavMeshSurface

 * NavMeshModifier

 * NavMeshModifierVolume

 * NavMeshLink

 * NavMeshObstacle

 

 * We can set Agent type.. meaning that each agent has its own path

 * Using Modifier, we can adjust each game object in detail. ( has options like Ignore build, override ..)

 * ModifierVolume is a component that affects baking.

 * Use NavMeshObstacle when you want to calculate the path dynacally ( meaning being able to determine the path right before     moving)

 * NavMeshSurface has a method "BuildNavMesh", which we can use in code to build NavMesh on the fly.

   

 * Basic Code snipet:

         if (Input.GetMouseButtonDown(0))
        {
            Ray ray = cam.ScreenPointToRay(Input.mousePosition);
            if (Physics.Raycast(ray, out RaycastHit hit))
            {
                agent.SetDestination(hit.point);
            }  
        }

*** Animation System

Two basic concept

 * Animation

 * Avatar

 

 * Animation has information of how to animate the skeleton (rig)

 * Avatar has a skeleton (rig)  - and optionally skins

 * If you have an animation and two or more avatar, the avatars can animate on the animation,

    so as a result all the avatars shows same motions based on the animation

   - This is called Retargetting. (see below)

* Workflow

  * prepare animations ( walk, run, jump)

  * prepare animator controllers ( how to operate the animations)

  * prepare avatars ( something that has similar bone structure that can match with animations)

  * make animator using animation controllers and avatars prepared.

** See: Character Animation Setup in unity tutorial and local folder on your computer

 ** One of the most powerful features of Mecanim is retargeting of humanoid animations

 ** Retargeting is only possible for humanoid models, where an Avatar
 has been configured

*** Vector3.Reflect

Description

Reflects a vector off the plane defined by a normal.

The inNormal vector defines a plane (a plane's normal is the vector that is perpendicular to its surface). the inDirection vector is treated as a directional arrow coming in to the plane. The returned value is a vector of equal magnitude to inDirection but with its direction reflected.


Reflection of a vector off a plane.

 * If you want your character to be level with ground, use Cross Product of Normal vector and the character's right vector

 *   this gives us forward vector

*** Quaternion Operation

Quaternion1 * Quaternion2 <- 일종의 덧셈, Quaternion1에 Quaternion2를 더한 방향값이 나온다.

Example:

float turn = m_TurnInputValue * m_TurnSpeed * Time.deltaTime;

// Make this into a rotation in the y axis.
Quaternion turnRotation = Quaternion.Euler(0f, turn, 0f);       

// Apply this rotation to the rigidbody's rotation.      
m_Rigidbody.MoveRotation(m_Rigidbody.rotation * turnRotation);