RefractionUnitTests.cc

TEST_CASE("Refraction straight through center from outside") {
    Vec3f rayDirection({ 0, 0, -1 });
    Vec3f normal({ 0, 0, 1 });
    bool isTotalInternalReflection;
    Vec3f refraction = refractionDir(rayDirection, normal, 1.2f, isTotalInternalReflection);
    REQUIRE(refraction[0] == 0);
    REQUIRE(refraction[1] == 0);
    REQUIRE(refraction[2] == -1);
    REQUIRE(!isTotalInternalReflection);
}


TEST_CASE("Refraction straight through center from inside") {
    Vec3f rayDirection({ 0, 0, -1 });
    Vec3f normal({ 0, 0, -1 });
    bool isTotalInternalReflection;
    Vec3f refraction = refractionDir(rayDirection, normal, 1.2f, isTotalInternalReflection);
    REQUIRE(refraction[0] == 0);
    REQUIRE(refraction[1] == 0);
    REQUIRE(refraction[2] == -1);
    REQUIRE(!isTotalInternalReflection);
}


TEST_CASE("Refraction at 45 degrees through glass slab") {
    Vec3f rayDirection = normalize(Vec3f({ 0, -sinf(M_PI / 4.0f), -cosf(M_PI / 4.0f) }));
    Vec3f normal({ 0, 0, 1 });
    bool isTotalInternalReflection;
    Vec3f refraction = refractionDir(rayDirection, normal, 1.5f, isTotalInternalReflection);
    REQUIRE(refraction[0] == 0);
    REQUIRE(refraction[1] == Approx(-sinf(M_PI / 6.0f)).margin(0.03f));
    REQUIRE(refraction[2] == Approx(-cosf(M_PI / 6.0f)).margin(0.03f));
    REQUIRE(!isTotalInternalReflection);

    refraction = refractionDir(refraction, multiply(normal, -1), 1.5f, isTotalInternalReflection);
    REQUIRE(refraction[0] == Approx(rayDirection[0]));
    REQUIRE(refraction[1] == Approx(rayDirection[1]));
    REQUIRE(refraction[2] == Approx(rayDirection[2]));
    REQUIRE(!isTotalInternalReflection);
}


TEST_CASE("Refraction at 75 degrees from normal through glass slab") {
    Vec3f rayDirection = normalize(Vec3f({ 0, -sinf(5.0f * M_PI / 12.0f), -cosf(5.0f * M_PI / 12.0f) }));
    Vec3f normal({ 0, 0, 1 });
    bool isTotalInternalReflection;
    Vec3f refraction = refractionDir(rayDirection, normal, 1.5f, isTotalInternalReflection);
    REQUIRE(refraction[0] == 0);
    REQUIRE(refraction[1] == Approx(-sinf(40.0f * M_PI / 180.0f)).margin(0.03f));
    REQUIRE(refraction[2] == Approx(-cosf(40.0f * M_PI / 180.0f)).margin(0.03f));
    REQUIRE(!isTotalInternalReflection);

    refraction = refractionDir(refraction, multiply(normal, -1), 1.5f, isTotalInternalReflection);
    REQUIRE(refraction[0] == Approx(rayDirection[0]));
    REQUIRE(refraction[1] == Approx(rayDirection[1]));
    REQUIRE(refraction[2] == Approx(rayDirection[2]));
    REQUIRE(!isTotalInternalReflection);
}


TEST_CASE("Refraction at 45 degrees from normal below glass slab") {
    Vec3f rayDirection = normalize(Vec3f({ 0, sinf(M_PI / 4.0f), -cosf(M_PI / 4.0f) }));
    printf("ray direction: %f %f %f\n", REST(rayDirection));
    Vec3f normal({ 0, 0, 1 });
    bool isTotalInternalReflection;
    Vec3f refraction = refractionDir(rayDirection, normal, 1.5f, isTotalInternalReflection);
    printf("RESULT: %f %f %f %d %f\n", REST(refraction), isTotalInternalReflection, norm(refraction));
    REQUIRE(refraction[0] == 0);
    REQUIRE(refraction[1] == Approx(sinf(M_PI / 6.0f)).margin(0.03f));
    REQUIRE(refraction[2] == Approx(-cosf(M_PI / 6.0f)).margin(0.03f));
    REQUIRE(!isTotalInternalReflection);

    refraction = refractionDir(refraction, multiply(normal, -1), 1.5f, isTotalInternalReflection);
    REQUIRE(refraction[0] == Approx(rayDirection[0]));
    REQUIRE(refraction[1] == Approx(rayDirection[1]));
    REQUIRE(refraction[2] == Approx(rayDirection[2]));
    REQUIRE(!isTotalInternalReflection);
}


TEST_CASE("Total internal reflection") {
    Vec3f rayDirection = normalize(Vec3f({ 0, sinf(M_PI / 4.0f), -cosf(M_PI / 4.0f) }));
    Vec3f normal({ 0, 0, -1 });
    bool isTotalInternalReflection;
    Vec3f refraction = refractionDir(rayDirection, normal, 1.5f, isTotalInternalReflection);
    REQUIRE(isTotalInternalReflection);

    rayDirection = normalize(Vec3f({ 0, sinf(M_PI / 3.0f), -cosf(M_PI / 3.0f) }));
    isTotalInternalReflection = false;
    refraction = refractionDir(rayDirection, normal, 1.5f, isTotalInternalReflection);
    REQUIRE(isTotalInternalReflection);
}


TEST_CASE("Just before total internal reflection") {
    Vec3f rayDirection = normalize(Vec3f({ 0, sinf(M_PI / 4.5f), -cosf(M_PI / 4.5f) }));
    Vec3f normal({ 0, 0, -1 });
    bool isTotalInternalReflection;
    Vec3f refraction = refractionDir(rayDirection, normal, 1.5f, isTotalInternalReflection);
    REQUIRE(!isTotalInternalReflection);
}