Third Person Camera

This blog is focused on creating third person view style controlled camera, which follows a user controlled object.

Making Third Person Camera

- Setting up the camera with important elements of view matrix and lookAt vector
    Camera::Camera(float fov, float aspect, float nearPlane, float farPlane)
    {     
         m_right  = { 0,0,0 };
         m_up  = { 0,0,0 };
         m_look  = { 0,0,0 };
         m_position = { 0,0,0 };
        m_Oldposition = { 0,0,0 };
        m_lookAt = { 0,0,0 };
        m_velocity = { 0,0,0 };
        SetLookAt(XMFLOAT3(0, 0, 5));
       #if _DEBUG
        m_maxVelocity = 0.5f;
      #else
        m_maxVelocity = 0.2f;
      #endif
       CreateProjectionMatrix(fov, aspect, nearPlane, farPlane);
       m_viewMatrix = { 1,0,0,0, 0,1,0,0, 0,0,1,0 ,0,0,0,1 };
   }    
 
- Positioning the camera and moving towards the player
   void Camera::MoveForward(float units)
     {   
         // Moving the camera through y axis while its lowering
          if (Y_Movement)
         {
                 m_velocity = m_velocity + m_look * units;
          }
        // Making a checks so that there is no change in y
          else
          {
                 XMFLOAT3 moveVector;
                 moveVector.x = m_look.x;
                 moveVector.y = 0.0f;
                 moveVector.z = m_look.z;
                 moveVector = Normalize(moveVector);
                 moveVector = moveVector * units;
                 m_velocity = m_velocity + moveVector;
            }
     }

- Create a new projection matrix with CreativePerspectiveFieldOfView. It controls how camera  coordinate values are transformed to screen coordinates
      void Camera::CreateProjectionMatrix(float fov, float aspect, float nearPlane, float farPlane)
     {
            m_fov = XMConvertToRadians(fov);
            m_aspect = aspect;
            m_nearPlane = nearPlane;
            m_farPlane = farPlane;
            XMStoreFloat4x4(&m_projection, XMMatrixPerspectiveFovLH(m_fov, aspect, nearPlane, farPlane));
      }
- Updating the camera
void Camera::Update(NavMesh * _nav)
{
    //Clamping how fast the camera is moving     if (vectorLength(m_velocity) > m_maxVelocity)
    {
            m_velocity = Normalize(m_velocity) * m_maxVelocity;
    }
    //MOVING     m_Oldposition = m_position;
     m_position = m_position + m_velocity;
     CameraBoundcheck(_nav);
   //STOP!    m_velocity = XMFLOAT3(m_velocity.x * .9f, m_velocity.y * .9f, m_velocity.z * .9f);
    m_lookAt = m_position + m_look;

    //Making new view Matrix    XMFLOAT4 up = { 0,1,0,1.0f };
    XMFLOAT4X4 temp;
    XMStoreFloat4x4(&temp, XMMatrixInverse(nullptr, XMLoadFloat4x4(&m_viewMatrix)));
    XMStoreFloat4x4(&m_viewMatrix, XMMatrixLookAtLH(XMLoadFloat3(&m_position), XMLoadFloat3(&m_lookAt), XMLoadFloat4(&up)));
    BuildViewFrustum();

    m_right.x = temp._11;
    m_right.y = temp._12;
    m_right.z = temp._13;
    m_up.x = temp._21;
    m_up.y = temp._22;
    m_up.z = temp._23;
    m_look.x = temp._31;
    m_look.y = temp._32;
   m_look.z = temp._33;
}