//
// Created by dawsh on 1/25/24.
//
#pragma once

#include "Plane.h"

namespace Geometry
{

    enum class FrustumType
    {
        Invalid,
        /// Set the Frustum type to this value to define the orthographic projection formula. In orthographic projection,
        /// 3D images are projected onto a 2D plane essentially by flattening the object along one direction (the plane normal).
        /// The size of the projected images appear the same independent of their distance to the camera, and distant objects will
        /// not appear smaller. The shape of the Frustum is identical to an oriented bounding box (OBB).
        Orthographic,
        /// Set the Frustum type to this value to use the perspective projection formula. With perspective projection, the 2D
        /// image is formed by projecting 3D points towards a single point (the eye point/tip) of the Frustum, and computing the
        /// point of intersection of the line of the projection and the near plane of the Frustum.
        /// This corresponds to the optics in the real-world, and objects become smaller as they move to the distance.
        /// The shape of the Frustum is a rectangular pyramid capped from the tip.
        Perspective
    };

    class Frustum {
    public:
        Plane TopFace;
        Plane BottomFace;
        Plane RightFace;
        Plane LeftFace;
        Plane FarFace;
        Plane NearFace;
        static Frustum CreateFrustumFromCamera(const Camera& cam, float aspect, float fovY, float zNear, float zFar);

    };

    Frustum Frustum::CreateFrustumFromCamera(const Camera &cam, float aspect, float fovY, float zNear, float zFar) {
        Frustum frustum;
        const float halfVSide = zFar * tanf(fovY * 0.5f);
        const float halfHSide = halfVSide * aspect;

        const Vector3 frontMultFar = cam.Front * zFar;

        frustum.NearFace  = Plane{cam.Position + cam.Front * zNear, cam.Front};
        frustum.FarFace   = Plane{cam.Position + frontMultFar, -cam.Front};
        frustum.RightFace = Plane{cam.Position, Vector3::Cross(frontMultFar - cam.Right * halfHSide, cam.Up)};
        frustum.LeftFace  = Plane{cam.Position, Vector3::Cross(cam.Up, frontMultFar+cam.Right*halfHSide)};
        frustum.TopFace   = Plane{cam.Position, Vector3::Cross(cam.Right, frontMultFar - cam.Up * halfVSide)};
        frustum.BottomFace   = Plane{cam.Position, Vector3::Cross(frontMultFar + cam.Up * halfVSide, cam.Right)};
        return frustum;
    }

}