#include "camera.h"

Camera::Camera() : mPos(0.0f,0.0f,0.0f),mViewCenter(0.0f,0.0f,-1.0f),mUp(0.0f,1.0f,0.0f)
{
	mbMoveLeft = false;
	mbMoveRight = false;
	mbMoveForward = false;
	mbMoveBack = false;
}

void Camera::Update(float deltaTime)
{
	float moveSpeed = 10.0f;

	//前方的向量
	Vector3f forwardDirection = mViewCenter - mPos;
	forwardDirection.Normalize();
	
	//右方的向量
	Vector3f rightDirection = Cross(forwardDirection, mUp);
	rightDirection.Normalize();

	if (mbMoveLeft) {
		Vector3f delta = rightDirection * deltaTime * moveSpeed;
		mPos = mPos - delta;
		mViewCenter = mViewCenter - delta;
	}

	if (mbMoveRight) {
		Vector3f delta = rightDirection * deltaTime * moveSpeed;
		mPos = mPos + delta;
		mViewCenter = mViewCenter + delta;
	}

	if (mbMoveForward) {
		Vector3f delta = forwardDirection * deltaTime * moveSpeed;
		mPos = mPos + delta;
		mViewCenter = mViewCenter + delta;
	}

	if (mbMoveBack) {
		Vector3f delta = forwardDirection * deltaTime * moveSpeed;
		mPos = mPos - delta;
		mViewCenter = mViewCenter - delta;
	}

	glLoadIdentity();
	gluLookAt(
		mPos.x, mPos.y, mPos.z,
		mViewCenter.x, mViewCenter.y, mViewCenter.z,
		mUp.x, mUp.y, mUp.z
	);

}

void Camera::Picth(float angle)
{
	Vector3f viewDirection = mViewCenter - mPos;
	viewDirection.Normalize();
	Vector3f rightDirection = Cross(viewDirection, mUp);
	rightDirection.Normalize();
	RotateView(angle, rightDirection.x, rightDirection.y, rightDirection.z);
}

void Camera::Yaw(float angle)
{
	RotateView(angle, mUp.x, mUp.y, mUp.z);
}

void Camera::RotateView(float angle, float x, float y, float z)
{
	Vector3f viewDirection = mViewCenter - mPos;
	Vector3f newDirection(0.0f, 0.0f, 0.0f);

	float C = cosf(angle);
	float S = sinf(angle);

	Vector3f tempX(C + x*x*(1-C), x*y*(1-C)-z*S,x*z*(1-C)+y*S);
	newDirection.x = tempX*viewDirection;

	Vector3f tempY(x*y*(1-C)+z*S, C+y*y*(1-C),y*z*(1-C)-x*S);
	newDirection.y = tempY * viewDirection;

	Vector3f tempZ(x*z*(1-C)-y*S, y*z*(1-C)+x*S, C+z*z*(1-C));
	newDirection.z = tempZ* viewDirection;

	mViewCenter = mPos + newDirection;
}

void Camera::SwitchTo3D()
{
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(50.0f, (float)mViewportWidth / (float)mViewportHeight, 0.1f, 1000.0f);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
}

void Camera::SwitchTo2D()
{
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(-mViewportWidth / 2, mViewportWidth / 2, -mViewportHeight / 2, mViewportHeight / 2);
	glMatrixMode();
	glLoadIdentity();
}