//Plane.h
#pragma once
#include "glm/glm.hpp"
class Plane
{
public:
	float d;
	glm::vec3 normal;
	Plane() {
		this->normal = glm::vec3(0);
		this->d = 0;
	};
	void set3Points(glm::vec3 p0, glm::vec3 p1, glm::vec3 p2) {
		this->normal = glm::normalize(glm::cross(p1 - p0, p2 - p0));
		this->d = glm::dot(-this->normal, p0);
	};
	void setNormalAndPoint(glm::vec3 normal, glm::vec3 point) {
		this->normal = normal;
		this->d = glm::dot(-this->normal, point);
	};
};

//Frustum.h
#include "glm/glm.hpp"
#include "Plane.h"
class Frustum
{
private:
	enum {
		TOP = 0, BOTTOM, LEFT,
		RIGHT, NEARPLANE, FARPLANE
	};
	static enum { OUTSIDE, INTERSECT, INSIDE };
	Plane plane[6];
	glm::vec3 nearTopLeft, nearTopRight, nearBottomLeft, nearBottomRight, farTopLeft, farTopRight, farBottomLeft, farBottomRight;
	float nearDistance, farDistance, ratio, viewAngle;
	float nearWidth, nearHeight, farWidth, farHeight;
public:
	Frustum(float viewAngle, float ratio, float nearDistance, float farDistance);
	void setCamDef(glm::vec3 pos, glm::vec3 dir, glm::vec3 up, glm::vec3 right);
	bool pointInFrustum(glm::vec3 point);
	bool sphereInFrustum(glm::vec3 center, float radius);
	//int boxInFrustum(AABox &b);
};

//Frustum.cpp
#include "Frustum.h"

Frustum::Frustum(float viewAngle, float ratio, float nearDistance, float farDistance)
{
	// store the information
	this->ratio = ratio;
	this->viewAngle = viewAngle;
	this->nearDistance = nearDistance;
	this->farDistance = farDistance;

	// compute width and height of the near and far plane sections
	float tangHolder = glm::tan(glm::radians(this->viewAngle) / 2);
	this->nearHeight = tangHolder * this->nearDistance;
	this->nearWidth = this->nearHeight * this->ratio;
	this->farHeight = tangHolder * this->farDistance;
	this->farWidth = this->farHeight * this->ratio;
}

void Frustum::setCamDef(glm::vec3 pos, glm::vec3 dir, glm::vec3 up, glm::vec3 right)
{
	glm::vec3 vectorHolder, normalHolder;
	glm::vec3 nearCenter = pos + dir * this->nearDistance;
	glm::vec3 farCenter = pos + dir * this->farDistance;

	this->plane[NEARPLANE].setNormalAndPoint(-dir, nearCenter);
	this->plane[FARPLANE].setNormalAndPoint(dir, farCenter);

	vectorHolder = glm::normalize((nearCenter + up * this->nearHeight) - pos);
	normalHolder = glm::cross(right, vectorHolder);
	this->plane[TOP].setNormalAndPoint(normalHolder, pos);

	vectorHolder = glm::normalize((nearCenter - up * this->nearHeight) - pos);
	normalHolder = glm::cross(vectorHolder, right);
	this->plane[BOTTOM].setNormalAndPoint(normalHolder, pos);

	vectorHolder = glm::normalize((nearCenter - right * this->nearWidth) - pos);
	normalHolder = glm::cross(up, vectorHolder);
	this->plane[LEFT].setNormalAndPoint(normalHolder, pos);

	vectorHolder = glm::normalize((nearCenter + right * this->nearWidth) - pos);
	normalHolder = glm::cross(vectorHolder, up);
	this->plane[RIGHT].setNormalAndPoint(normalHolder, pos);
}

bool Frustum::pointInFrustum(glm::vec3 point)
{
	if (0 >= glm::dot(this->plane[FARPLANE].normal, point) + this->plane[FARPLANE].d
		&& 0 >= glm::dot(this->plane[NEARPLANE].normal, point) + this->plane[NEARPLANE].d
		&& 0 >= glm::dot(this->plane[TOP].normal, point) + this->plane[TOP].d
		&& 0 >= glm::dot(this->plane[BOTTOM].normal, point) + this->plane[BOTTOM].d
		&& 0 >= glm::dot(this->plane[RIGHT].normal, point) + this->plane[RIGHT].d
		&& 0 >= glm::dot(this->plane[LEFT].normal, point) + this->plane[LEFT].d)
	{
		return true;
	}
	else
	{
		return false;
	}
}

bool Frustum::sphereInFrustum(glm::vec3 center, float radius)
{
	if (0 >= glm::dot(this->plane[FARPLANE].normal, center - this->plane[FARPLANE].normal * 0.5f) + this->plane[FARPLANE].d
		&& 0 >= glm::dot(this->plane[NEARPLANE].normal, center) + this->plane[NEARPLANE].d
		&& 0 >= glm::dot(this->plane[TOP].normal, center - this->plane[TOP].normal * radius * 1.5f) + this->plane[TOP].d
		&& 0 >= glm::dot(this->plane[BOTTOM].normal, center) + this->plane[BOTTOM].d
		&& 0 >= glm::dot(this->plane[RIGHT].normal, center) + this->plane[RIGHT].d
		&& 0 >= glm::dot(this->plane[LEFT].normal, center) + this->plane[LEFT].d)
	{
		return true;
	}
	else
	{
		return false;
	}
}