#include"FirstCameraClass.h"

FirstCameraClass::FirstCameraClass()
{
	//初始化第一人稱相機的引數，剛開始相機是位於中間的
	mPosition = XMFLOAT3(0.f, 0.0f, -5.0f);
	mRight = XMFLOAT3(1.0f, 0.0f, 0.0f);
	mUp = XMFLOAT3(0.0f, 1.0f, 0.0f);
    mLook= XMFLOAT3(0.0f, 0.0f, 1.0f);
}

FirstCameraClass::FirstCameraClass(const FirstCameraClass&other)
{

}

FirstCameraClass::~FirstCameraClass()
{

}

//相機位置
void FirstCameraClass::SetPosition(float x, float y, float z)
{
	mPosition.x = x;
	mPosition.y = y;
	mPosition.z = z;
}


void FirstCameraClass::SetPosition(const XMFLOAT3& v)
{
	mPosition = v;
}


XMFLOAT3 FirstCameraClass::GetPosition()const
{
	return mPosition;
}

XMVECTOR FirstCameraClass::GetPositionXM()const
{
	return XMLoadFloat3(&mPosition);
}



//獲取相機的基礎向量(Up,Look,Right)
XMFLOAT3 FirstCameraClass::GetUp()const
{
	return mUp;
}
XMVECTOR FirstCameraClass::GetUpXM()const
{
	return XMLoadFloat3(&mUp);
}


XMFLOAT3 FirstCameraClass::GetLook()const
{
	return mLook;
}
XMVECTOR FirstCameraClass::GetLookXM()const
{
	return XMLoadFloat3(&mLook);
}


XMFLOAT3 FirstCameraClass::GetRight()const
{

	return mRight;
}

XMVECTOR FirstCameraClass::GetRightXM()const
{
	return XMLoadFloat3(&mRight);
}

//獲取相機變換矩陣
XMMATRIX FirstCameraClass::GetViewMatrix()const
{
	return mViewMatrix;
}

//通過相機在世界空間的位置，目標點，以及上向量來定義相機變換矩陣
void FirstCameraClass::LookAt(FXMVECTOR pos, FXMVECTOR target, FXMVECTOR worldUp)
{
	
	XMVECTOR Look = XMVectorSubtract(target, pos);
	XMVECTOR Up = worldUp;
	XMVECTOR Right = XMVector3Cross(Up, Look);
	Up = XMVector3Cross(Look, Right);

	//規格化三個先來
	XMVector3Normalize(Look);
	XMVector3Normalize(Up);
	XMVector3Normalize(Right);

	//將引數存入Camera類中
	XMStoreFloat3(&mPosition, pos);
	XMStoreFloat3(&mLook, Look);
	XMStoreFloat3(&mUp, Up);
	XMStoreFloat3(&mRight, Right);

}


//往相機座標系Look的方向前進或者後退,然後此時Look,Up,Right都不改變,僅僅是位置在改變
void FirstCameraClass::Walk(float d)
{
	//mPosition+=d*mLook
	//XMVectorReplicate返回的是XMVECTOR(d,d,d,d)
	XMVECTOR s = XMVectorReplicate(d);
	XMVECTOR l = XMLoadFloat3(&mLook);
	XMVECTOR p = XMLoadFloat3(&mPosition);
    
	//XMVectorMultiplyAdd(v1,v2,v3)=v1*v2+v3
	XMStoreFloat3(&mPosition, XMVectorMultiplyAdd(s, l, p));
}

//往相機座標系Right方向前進或者後退,然後此時Look,Up,Right都不改變,僅僅是位置在改變
void FirstCameraClass::Strafe(float d)
{
	//mPosition+=d*mRight
	//XMVectorReplicate返回的是XMVECTOR(d,d,d,d)
	XMVECTOR s = XMVectorReplicate(d);
	XMVECTOR r = XMLoadFloat3(&mRight);
	XMVECTOR p = XMLoadFloat3(&mPosition);

	//XMVectorMultiplyAdd(v1,v2,v3)=v1*v2+v3
	XMStoreFloat3(&mPosition, XMVectorMultiplyAdd(s, r, p));
}

//相機上下的移動是位置在Y值上的改變，而Look,Up,Right都不改變,僅僅是位置在改變
void FirstCameraClass::UpDown(float d)
{

	//mPosition+=d*up
	//XMVectorReplicate返回的是XMVECTOR(d,d,d,d)
	XMVECTOR s = XMVectorReplicate(d);
	XMVECTOR up = XMVectorSet(0.0f, 1.0f, 0.0f,0.0f);
	XMVECTOR p = XMLoadFloat3(&mPosition);

	//XMVectorMultiplyAdd(v1,v2,v3)=v1*v2+v3
	XMStoreFloat3(&mPosition, XMVectorMultiplyAdd(s, up, p));
}


//Look和Up向量繞相機座標系的right向量進行旋轉，此時look和up向量改變，而right和poisiton不改變
void FirstCameraClass::Pitch(float angle)
{
	XMMATRIX R = XMMatrixRotationAxis(XMLoadFloat3(&mRight), angle);
	XMStoreFloat3(&mLook, XMVector3TransformNormal(XMLoadFloat3(&mLook), R));
	XMStoreFloat3(&mUp, XMVector3TransformNormal(XMLoadFloat3(&mUp), R));
} 

//繞世界座標系的Y軸進行旋轉(而非相機座標系的Up向量,這點容易受到慣性思維而誤解，實在無法理解就用人的視角在現實世界是怎麼旋轉的粒子解釋),look,up,right繞Y軸進行旋轉，位置不變
void FirstCameraClass::RotateY(float angle)
{
	XMMATRIX R = XMMatrixRotationY(angle);
	XMStoreFloat3(&mLook, XMVector3TransformNormal(XMLoadFloat3(&mLook), R));
	XMStoreFloat3(&mUp, XMVector3TransformNormal(XMLoadFloat3(&mUp), R));
	XMStoreFloat3(&mRight, XMVector3TransformNormal(XMLoadFloat3(&mRight), R));
}

void FirstCameraClass::UpdateViewMatrix()
{
	XMVECTOR R = XMLoadFloat3(&mRight);
	XMVECTOR U = XMLoadFloat3(&mUp);
	XMVECTOR L = XMLoadFloat3(&mLook);
	XMVECTOR P = XMLoadFloat3(&mPosition);

	//正交規格化right,look,up
	
	//規格化look向量
	L = XMVector3Normalize(L);
	
	//U=look(X)right
	U = XMVector3Normalize(XMVector3Cross(L, R));

	//R=up(X)look
	R= XMVector3Normalize(XMVector3Cross(U, L));

	//求出相機變換矩陣某些引數裡面的點積
	float x = -XMVectorGetX(XMVector3Dot(P, R));
	float y = -XMVectorGetX(XMVector3Dot(P, U));
	float z = -XMVectorGetX(XMVector3Dot(P, L));

	//第一列
	mViewMatrix(0, 0) = mRight.x;
	mViewMatrix(1, 0) = mRight.y;
	mViewMatrix(2, 0) = mRight.z;
	mViewMatrix(3, 0) = x;

	//第二列
	mViewMatrix(0, 1) = mUp.x;
	mViewMatrix(1, 1) = mUp.y;
	mViewMatrix(2, 1) = mUp.z;
	mViewMatrix(3, 1) = y;

	//第三列
	mViewMatrix(0, 2) = mLook.x;
	mViewMatrix(1, 2) = mLook.y;
	mViewMatrix(2, 2) = mLook.z;
	mViewMatrix(3, 2) = z;

	//第四列
	mViewMatrix(0, 3) = 0;
	mViewMatrix(1, 3) = 0;
	mViewMatrix(2, 3) = 0;
	mViewMatrix(3, 3) = 1.0f;
}


XMMATRIX FirstCameraClass::GetBaseViewMatrix()const
{
	return mBaseViewMatrix;
}

//更新相機變換矩陣
void FirstCameraClass::UpdateBaseViewMatrix()
{
	//上向量,位置向量,觀察向量
	XMVECTOR Up, Postion, LookAt;

	//設定相機的位置
	Postion = XMVectorSet(0.0f, 0.0f, -1.0f, 0.0f);
	LookAt = XMVectorSet(0.0f, 0.0f, 1.0f, 0.0f);
	Up = XMVectorSet(0.0f, 1.0f, 0.0f, 0.0f);

	//最後建立ViewMatrix
	mBaseViewMatrix = XMMatrixLookAtLH(Postion, LookAt, Up);
}