// ----------------------------------------------------------------

// From Game Programming in C++ by Sanjay Madhav

// Copyright (C) 2017 Sanjay Madhav. All rights reserved.

//

// Released under the BSD License

// See LICENSE in root directory for full details.

// ----------------------------------------------------------------

#include "OrbitCamera.h"

#include "Actor.h"

OrbitCamera::OrbitCamera(Actor* owner)

:CameraComponent(owner)

,mOffset(-400.0f, 0.0f, 0.0f)

,mUp(Vector3::UnitZ)

,mPitchSpeed(0.0f)

,mYawSpeed(0.0f)

{

}

void OrbitCamera::Update(float deltaTime)

{

CameraComponent::Update(deltaTime);

// Create a quaternion for yaw about world up

Quaternion yaw(Vector3::UnitZ, mYawSpeed * deltaTime);

// Transform offset and up by yaw

mOffset = Vector3::Transform(mOffset, yaw);

mUp = Vector3::Transform(mUp, yaw);

// Compute camera forward/right from these vectors

// Forward owner.position - (owner.position + offset)

// = -offset

Vector3 forward = -1.0f * mOffset;

forward.Normalize();

Vector3 right = Vector3::Cross(mUp, forward);

right.Normalize();

// Create quaternion for pitch about camera right

Quaternion pitch(right, mPitchSpeed * deltaTime);

// Transform camera offset and up by pitch

mOffset = Vector3::Transform(mOffset, pitch);

mUp = Vector3::Transform(mUp, pitch);

// Compute transform matrix

Vector3 target = mOwner->GetPosition();

Vector3 cameraPos = target + mOffset;

Matrix4 view = Matrix4::CreateLookAt(cameraPos, target, mUp);

SetViewMatrix(view);

}