/*!
 * 05_rays.cpp
 *
 * Copyright (c) 2015-2024, NADAL Jean-Baptiste. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301 USA
 *
 * @Author:  NADAL Jean-Baptiste
 * @Date: 05/02/2024
 *
 */

/*---------------------------------------------------------------------------*/

#include <catch.hpp>

#include "raytracing.h"

using namespace Raytracer;

/* ------------------------------------------------------------------------- */

/* ------------------------------------------------------------------------- */

TEST_CASE("[05][Rays] Creating and querying a ray", "[Rays]")
{
    Tuple origin = Tuple::Point(1, 2, 3);
    Tuple direction = Tuple::Vector(4, 5, 6);
    Ray r(origin, direction);

    REQUIRE(r.origin() == origin);
    REQUIRE(r.direction() == direction);
}

/* ------------------------------------------------------------------------- */

TEST_CASE("[05][Rays] Computing a point from a distance", "[Rays]")
{
    Ray r(Tuple::Point(2, 3, 4), Tuple::Vector(1, 0, 0));

    REQUIRE(r.position(0) == Tuple::Point(2, 3, 4));
    REQUIRE(r.position(1) == Tuple::Point(3, 3, 4));
    REQUIRE(r.position(-1) == Tuple::Point(1, 3, 4));
    REQUIRE(r.position(2.5) == Tuple::Point(4.5, 3, 4));
}

/* ------------------------------------------------------------------------- */

TEST_CASE("[05][Rays] a ray intersects a sphere at two points", "[Rays]")
{
    Ray r(Tuple::Point(0, 0, -5), Tuple::Vector(0, 0, 1));
    Sphere s;
    auto xs = r.intersect(s);

    REQUIRE(xs.size() == 2);
    REQUIRE(xs[0] == 4.0);
    REQUIRE(xs[1] == 6.0);
}

/* ------------------------------------------------------------------------- */

TEST_CASE("[05][Rays] a ray intersects a sphere at a tangent", "[Rays]")
{
    Ray r(Tuple::Point(0, 1, -5), Tuple::Vector(0, 0, 1));
    Sphere s;
    auto xs = r.intersect(s);

    REQUIRE(xs.size() == 2);
    REQUIRE(xs[0] == 5.0);
    REQUIRE(xs[1] == 5.0);
}

/* ------------------------------------------------------------------------- */

TEST_CASE("[05][Rays] a ray misses a sphere", "[Rays]")
{
    Ray r(Tuple::Point(0, 2, -5), Tuple::Vector(0, 0, 1));
    Sphere s;
    auto xs = r.intersect(s);

    REQUIRE(xs.size() == 0);
}

/* ------------------------------------------------------------------------- */

TEST_CASE("[05][Rays] a originates inside a sphere", "[Rays]")
{
    Ray r(Tuple::Point(0, 0, 0), Tuple::Vector(0, 0, 1));
    Sphere s;
    auto xs = r.intersect(s);

    REQUIRE(xs.size() == 2);
    REQUIRE(xs[0] == -1.0);
    REQUIRE(xs[1] == 1.0);
}

/* ------------------------------------------------------------------------- */

TEST_CASE("[05][Rays] a sphere is behind a ray", "[Rays]")
{
    Ray r(Tuple::Point(0, 0, 5), Tuple::Vector(0, 0, 1));
    Sphere s;
    auto xs = r.intersect(s);

    REQUIRE(xs.size() == 2);
    REQUIRE(xs[0] == -6.0);
    REQUIRE(xs[1] == -4.0);
}