raytracer_challenge/tests/05_rays.cpp

/*!
 * 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", "[Sphere]")
{
    Ray r(Tuple::Point(0, 0, -5), Tuple::Vector(0, 0, 1));
    Sphere s;
    Intersections xs = r.intersect(s);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

TEST_CASE("[05][Rays] Test Sphere Object", "[Sphere]")
{
    Sphere s1;
    Sphere s2 = s1;
    Sphere s3;

    REQUIRE(s1 == s2);
    REQUIRE(s1 != s3);
}

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

TEST_CASE("[05][Rays] An intersection encapsulates t and object", "[Intersections]")
{
    Sphere s;
    Intersection i(3.5, s);

    REQUIRE(i.distance_t() == 3.5);
    REQUIRE(i.object() == s);
}

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

TEST_CASE("[05][Rays] Aggregating intersections", "[Intersections]")
{
    Sphere s;
    Intersection i1(1, s);
    Intersection i2(2, s);
    Intersections xs = Intersections({i1, i2});

    REQUIRE(xs.count() == 2);
    REQUIRE(xs[0].distance_t() == 1);
    REQUIRE(xs[1].distance_t() == 2);
}

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

TEST_CASE("[05][Rays] Intersect set the object on the intersection", "[Intersections]")
{
    Ray r(Tuple::Point(0, 0, 5), Tuple::Vector(0, 0, 1));
    Sphere s;
    Intersections xs = r.intersect(s);

    REQUIRE(xs.count() == 2);
    REQUIRE(xs[0].object() == s);
    REQUIRE(xs[1].object() == s);
}

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

TEST_CASE("[05][Rays] The hit, when all intersections have positive t", "[Intersections]")
{
    Sphere s;
    Intersection i1(1, s);
    Intersection i2(2, s);
    Intersections xs = Intersections({i2, i1});

    Intersection i = xs.hit();

    REQUIRE(i == i1);
}

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

TEST_CASE("[05][Rays] The hit, when some intersections have negative t", "[Intersections]")
{
    Sphere s;
    Intersection i1(-1, s);
    Intersection i2(1, s);
    Intersections xs = Intersections({i2, i1});

    Intersection i = xs.hit();

    REQUIRE(i == i2);
}

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

TEST_CASE("[05][Rays] The hit, when all intersections have negative t", "[Intersections]")
{
    Sphere s;
    Intersection i1(-2, s);
    Intersection i2(-1, s);
    Intersections xs = Intersections({i1, i2});

    Intersection i = xs.hit();

    REQUIRE(i.object().is_nothing());
}

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

TEST_CASE("[05][Rays] The hit is always the lowest nonnegative intersection", "[Intersections]")
{
    Sphere s;
    Intersection i1(5, s);
    Intersection i2(7, s);
    Intersection i3(-3, s);
    Intersection i4(2, s);
    Intersections xs = Intersections({i1, i2, i3, i4});

    Intersection i = xs.hit();

    REQUIRE(i == i4);
}