Disable on-model supports for pierce tests.

Also added separate main for sla_print testsuite to speed up compilation.
2025-10-31 04:31:15 -06:00 · 2019-10-04 18:14:19 +02:00 · 2019-10-04 18:14:19 +02:00 · a34ca42709
commit a34ca42709
parent 1df1ef481d
3 changed files with 51 additions and 9 deletions
--- a/tests/sla_print/sla_print_tests.cpp
+++ b/tests/sla_print/sla_print_tests.cpp
@ -0,0 +1,647 @@
+#include <catch2/catch.hpp>
+
+#include <unordered_set>
+#include <unordered_map>
+#include <random>
+
+// Debug
+#include <fstream>
+
+#include "libslic3r/libslic3r.h"
+#include "libslic3r/Format/OBJ.hpp"
+#include "libslic3r/SLAPrint.hpp"
+#include "libslic3r/TriangleMesh.hpp"
+#include "libslic3r/SLA/SLAPad.hpp"
+#include "libslic3r/SLA/SLASupportTreeBuilder.hpp"
+#include "libslic3r/SLA/SLASupportTreeBuildsteps.hpp"
+#include "libslic3r/SLA/SLAAutoSupports.hpp"
+#include "libslic3r/SLA/SLARaster.hpp"
+#include "libslic3r/MTUtils.hpp"
+
+#include "libslic3r/SVG.hpp"
+#include "libslic3r/Format/OBJ.hpp"
+
+#if defined(WIN32) || defined(_WIN32)
+#define PATH_SEPARATOR R"(\)"
+#else
+#define PATH_SEPARATOR R"(/)"
+#endif
+
+namespace  {
+using namespace Slic3r;
+
+TriangleMesh load_model(const std::string &obj_filename)
+{
+    TriangleMesh mesh;
+    auto fpath = TEST_DATA_DIR PATH_SEPARATOR + obj_filename;
+    load_obj(fpath.c_str(), &mesh);
+    return mesh;
+}
+
+enum e_validity {
+    ASSUME_NO_EMPTY = 1,
+    ASSUME_MANIFOLD = 2,
+    ASSUME_NO_REPAIR = 4
+};
+
+void check_validity(const TriangleMesh &input_mesh,
+                    int flags = ASSUME_NO_EMPTY | ASSUME_MANIFOLD |
+                                ASSUME_NO_REPAIR)
+{
+    TriangleMesh mesh{input_mesh};
+
+    if (flags & ASSUME_NO_EMPTY) {
+        REQUIRE_FALSE(mesh.empty());
+    } else if (mesh.empty())
+        return; // If it can be empty and it is, there is nothing left to do.
+
+    REQUIRE(stl_validate(&mesh.stl));
+
+    bool do_update_shared_vertices = false;
+    mesh.repair(do_update_shared_vertices);
+
+    if (flags & ASSUME_NO_REPAIR) {
+        REQUIRE_FALSE(mesh.needed_repair());
+    }
+
+    if (flags & ASSUME_MANIFOLD) {
+        mesh.require_shared_vertices();
+        if (!mesh.is_manifold()) mesh.WriteOBJFile("non_manifold.obj");
+        REQUIRE(mesh.is_manifold());
+    }
+}
+
+struct PadByproducts
+{
+    ExPolygons   model_contours;
+    ExPolygons   support_contours;
+    TriangleMesh mesh;
+};
+
+void test_pad(const std::string &   obj_filename,
+              const sla::PadConfig &padcfg,
+              PadByproducts &       out)
+{
+    REQUIRE(padcfg.validate().empty());
+
+    TriangleMesh mesh = load_model(obj_filename);
+
+    REQUIRE_FALSE(mesh.empty());
+
+    // Create pad skeleton only from the model
+    Slic3r::sla::pad_blueprint(mesh, out.model_contours);
+
+    REQUIRE_FALSE(out.model_contours.empty());
+
+    // Create the pad geometry for the model contours only
+    Slic3r::sla::create_pad({}, out.model_contours, out.mesh, padcfg);
+
+    check_validity(out.mesh);
+
+    auto bb = out.mesh.bounding_box();
+    REQUIRE(bb.max.z() - bb.min.z() == Approx(padcfg.full_height()));
+}
+
+void test_pad(const std::string &   obj_filename,
+              const sla::PadConfig &padcfg = {})
+{
+    PadByproducts byproducts;
+    test_pad(obj_filename, padcfg, byproducts);
+}
+
+struct SupportByproducts
+{
+    std::string             obj_fname;
+    std::vector<float>      slicegrid;
+    std::vector<ExPolygons> model_slices;
+    sla::SupportTreeBuilder supporttree;
+    TriangleMesh            input_mesh;
+};
+
+const constexpr float CLOSING_RADIUS = 0.005f;
+
+void check_support_tree_integrity(const sla::SupportTreeBuilder &stree,
+                                  const sla::SupportConfig &cfg)
+{
+    double gnd  = stree.ground_level;
+    double H1   = cfg.max_solo_pillar_height_mm;
+    double H2   = cfg.max_dual_pillar_height_mm;
+
+    for (const sla::Head &head : stree.heads()) {
+        REQUIRE((!head.is_valid() || head.pillar_id != sla::ID_UNSET ||
+                 head.bridge_id != sla::ID_UNSET));
+    }
+
+    for (const sla::Pillar &pillar : stree.pillars()) {
+        if (std::abs(pillar.endpoint().z() - gnd) < EPSILON) {
+            double h = pillar.height;
+
+            if (h > H1) REQUIRE(pillar.links >= 1);
+            else if(h > H2) { REQUIRE(pillar.links >= 2); }
+        }
+
+        REQUIRE(pillar.links <= cfg.pillar_cascade_neighbors);
+        REQUIRE(pillar.bridges <= cfg.max_bridges_on_pillar);
+    }
+
+    double max_bridgelen = 0.;
+    auto chck_bridge = [&cfg](const sla::Bridge &bridge, double &max_brlen) {
+        Vec3d n = bridge.endp - bridge.startp;
+        double d = sla::distance(n);
+        max_brlen = std::max(d, max_brlen);
+
+        double z     = n.z();
+        double polar = std::acos(z / d);
+        double slope = -polar + PI / 2.;
+        REQUIRE(std::abs(slope) >= cfg.bridge_slope - EPSILON);
+    };
+
+    for (auto &bridge : stree.bridges()) chck_bridge(bridge, max_bridgelen);
+    REQUIRE(max_bridgelen <= cfg.max_bridge_length_mm);
+
+    max_bridgelen = 0;
+    for (auto &bridge : stree.crossbridges()) chck_bridge(bridge, max_bridgelen);
+
+    double md = cfg.max_pillar_link_distance_mm / std::cos(-cfg.bridge_slope);
+    REQUIRE(max_bridgelen <= md);
+}
+
+void test_supports(const std::string &       obj_filename,
+                   const sla::SupportConfig &supportcfg,
+                   SupportByproducts &       out)
+{
+    using namespace Slic3r;
+    TriangleMesh mesh = load_model(obj_filename);
+
+    REQUIRE_FALSE(mesh.empty());
+
+    TriangleMeshSlicer slicer{&mesh};
+
+    auto   bb      = mesh.bounding_box();
+    double zmin    = bb.min.z();
+    double zmax    = bb.max.z();
+    double gnd     = zmin - supportcfg.object_elevation_mm;
+    auto   layer_h = 0.05f;
+
+    out.slicegrid = grid(float(gnd), float(zmax), layer_h);
+    slicer.slice(out.slicegrid , CLOSING_RADIUS, &out.model_slices, []{});
+
+    // Create the special index-triangle mesh with spatial indexing which
+    // is the input of the support point and support mesh generators
+    sla::EigenMesh3D emesh{mesh};
+
+    // Create the support point generator
+    sla::SLAAutoSupports::Config autogencfg;
+    autogencfg.head_diameter = float(2 * supportcfg.head_front_radius_mm);
+    sla::SLAAutoSupports point_gen{emesh, out.model_slices, out.slicegrid,
+                                   autogencfg, [] {}, [](int) {}};
+
+    // Get the calculated support points.
+    std::vector<sla::SupportPoint> support_points = point_gen.output();
+
+    int validityflags = ASSUME_NO_REPAIR;
+
+    // If there is no elevation, support points shall be removed from the
+    // bottom of the object.
+    if (std::abs(supportcfg.object_elevation_mm) < EPSILON) {
+        sla::remove_bottom_points(support_points, zmin,
+                                  supportcfg.base_height_mm);
+    } else {
+        // Should be support points at least on the bottom of the model
+        REQUIRE_FALSE(support_points.empty());
+
+        // Also the support mesh should not be empty.
+        validityflags |= ASSUME_NO_EMPTY;
+    }
+
+    // Generate the actual support tree
+    sla::SupportTreeBuilder treebuilder;
+    treebuilder.build(sla::SupportableMesh{emesh, support_points, supportcfg});
+
+    check_support_tree_integrity(treebuilder, supportcfg);
+
+    const TriangleMesh &output_mesh = treebuilder.retrieve_mesh();
+
+    check_validity(output_mesh, validityflags);
+
+    // Quick check if the dimensions and placement of supports are correct
+    auto obb = output_mesh.bounding_box();
+
+    double allowed_zmin = zmin - supportcfg.object_elevation_mm;
+
+    if (std::abs(supportcfg.object_elevation_mm) < EPSILON)
+        allowed_zmin = zmin - 2 * supportcfg.head_back_radius_mm;
+
+    REQUIRE(obb.min.z() >= allowed_zmin);
+    REQUIRE(obb.max.z() <= zmax);
+
+    // Move out the support tree into the byproducts, we can examine it further
+    // in various tests.
+    out.obj_fname   = std::move(obj_filename);
+    out.supporttree = std::move(treebuilder);
+    out.input_mesh  = std::move(mesh);
+}
+
+void test_supports(const std::string &       obj_filename,
+                   const sla::SupportConfig &supportcfg = {})
+{
+    SupportByproducts byproducts;
+    test_supports(obj_filename, supportcfg, byproducts);
+}
+
+void export_failed_case(const std::vector<ExPolygons> &support_slices,
+                        const SupportByproducts &byproducts)
+{
+    for (size_t n = 0; n < support_slices.size(); ++n) {
+        const ExPolygons &sup_slice = support_slices[n];
+        const ExPolygons &mod_slice = byproducts.model_slices[n];
+        Polygons intersections = intersection(sup_slice, mod_slice);
+        
+        std::stringstream ss;
+        if (!intersections.empty()) {
+            ss << byproducts.obj_fname << std::setprecision(4) << n << ".svg";
+            SVG svg(ss.str());
+            svg.draw(sup_slice, "green");
+            svg.draw(mod_slice, "blue");
+            svg.draw(intersections, "red");
+            svg.Close();
+        }
+    }
+    
+    TriangleMesh m;
+    byproducts.supporttree.retrieve_full_mesh(m);
+    m.merge(byproducts.input_mesh);
+    m.repair();
+    m.require_shared_vertices();
+    m.WriteOBJFile(byproducts.obj_fname.c_str());
+}
+
+void test_support_model_collision(
+    const std::string &       obj_filename,
+    const sla::SupportConfig &input_supportcfg = {})
+{
+    SupportByproducts byproducts;
+
+    sla::SupportConfig supportcfg = input_supportcfg;
+
+    // Set head penetration to a small negative value which should ensure that
+    // the supports will not touch the model body.
+    supportcfg.head_penetration_mm = -0.15;
+    
+    // TODO: currently, the tailheads penetrating into the model body do not
+    // respect the penetration parameter properly. No issues were reported so
+    // far but we should definitely fix this.
+    supportcfg.ground_facing_only = true;
+
+    test_supports(obj_filename, supportcfg, byproducts);
+
+    // Slice the support mesh given the slice grid of the model.
+    std::vector<ExPolygons> support_slices =
+        byproducts.supporttree.slice(byproducts.slicegrid, CLOSING_RADIUS);
+
+    // The slices originate from the same slice grid so the numbers must match
+
+    bool support_mesh_is_empty =
+        byproducts.supporttree.retrieve_mesh(sla::MeshType::Pad).empty() &&
+        byproducts.supporttree.retrieve_mesh(sla::MeshType::Support).empty();
+    
+    if (support_mesh_is_empty)
+        REQUIRE(support_slices.empty());
+    else
+        REQUIRE(support_slices.size() == byproducts.model_slices.size());
+
+    bool notouch = true;
+    for (size_t n = 0; notouch && n < support_slices.size(); ++n) {
+        const ExPolygons &sup_slice = support_slices[n];
+        const ExPolygons &mod_slice = byproducts.model_slices[n];
+
+        Polygons intersections = intersection(sup_slice, mod_slice);
+
+        notouch = notouch && intersections.empty();
+    }
+    
+    if (!notouch) export_failed_case(support_slices, byproducts);
+
+    REQUIRE(notouch);
+}
+
+const char * const BELOW_PAD_TEST_OBJECTS[] = {
+    "20mm_cube.obj",
+    "V.obj",
+};
+
+const char * const AROUND_PAD_TEST_OBJECTS[] = {
+    "20mm_cube.obj",
+    "V.obj",
+    "frog_legs.obj",
+    "cube_with_concave_hole_enlarged.obj",
+};
+
+const char *const SUPPORT_TEST_MODELS[] = {
+    "cube_with_concave_hole_enlarged_standing.obj",
+    "A_upsidedown.obj",
+    "extruder_idler.obj"
+};
+
+} // namespace
+
+// Test pair hash for 'nums' random number pairs.
+template <class I, class II> void test_pairhash()
+{
+    const constexpr size_t nums = 1000;
+    I A[nums] = {0}, B[nums] = {0};
+    std::unordered_set<I> CH;
+    std::unordered_map<II, std::pair<I, I>> ints;
+
+    std::random_device rd;
+    std::mt19937 gen(rd());
+
+    const I Ibits = int(sizeof(I) * CHAR_BIT);
+    const II IIbits = int(sizeof(II) * CHAR_BIT);
+    const int bits = IIbits / 2 < Ibits ? Ibits / 2 : Ibits;
+
+    const I Imax = I(std::pow(2., bits) - 1);
+    std::uniform_int_distribution<I> dis(0, Imax);
+
+    for (size_t i = 0; i < nums;) {
+        I a = dis(gen);
+        if (CH.find(a) == CH.end()) { CH.insert(a); A[i] = a; ++i; }
+    }
+
+    for (size_t i = 0; i < nums;) {
+        I b = dis(gen);
+        if (CH.find(b) == CH.end()) { CH.insert(b); B[i] = b; ++i; }
+    }
+
+    for (size_t i = 0; i < nums; ++i) {
+        I a = A[i], b = B[i];
+
+        REQUIRE(a != b);
+
+        II hash_ab = sla::pairhash<I, II>(a, b);
+        II hash_ba = sla::pairhash<I, II>(b, a);
+        REQUIRE(hash_ab == hash_ba);
+
+        auto it = ints.find(hash_ab);
+
+        if (it != ints.end()) {
+            REQUIRE((
+                (it->second.first == a && it->second.second == b) ||
+                (it->second.first == b && it->second.second == a)
+            ));
+        } else
+            ints[hash_ab] = std::make_pair(a, b);
+    }
+}
+
+TEST_CASE("Pillar pairhash should be unique", "[SLASupportGeneration]") {
+    test_pairhash<int, long>();
+    test_pairhash<unsigned, unsigned>();
+    test_pairhash<unsigned, unsigned long>();
+}
+
+TEST_CASE("Flat pad geometry is valid", "[SLASupportGeneration]") {
+    sla::PadConfig padcfg;
+
+    // Disable wings
+    padcfg.wall_height_mm = .0;
+
+    for (auto &fname : BELOW_PAD_TEST_OBJECTS) test_pad(fname, padcfg);
+}
+
+TEST_CASE("WingedPadGeometryIsValid", "[SLASupportGeneration]") {
+    sla::PadConfig padcfg;
+
+    // Add some wings to the pad to test the cavity
+    padcfg.wall_height_mm = 1.;
+
+    for (auto &fname : BELOW_PAD_TEST_OBJECTS) test_pad(fname, padcfg);
+}
+
+TEST_CASE("FlatPadAroundObjectIsValid", "[SLASupportGeneration]") {
+    sla::PadConfig padcfg;
+
+    // Add some wings to the pad to test the cavity
+    padcfg.wall_height_mm = 0.;
+    // padcfg.embed_object.stick_stride_mm = 0.;
+    padcfg.embed_object.enabled = true;
+    padcfg.embed_object.everywhere = true;
+
+    for (auto &fname : AROUND_PAD_TEST_OBJECTS) test_pad(fname, padcfg);
+}
+
+TEST_CASE("WingedPadAroundObjectIsValid", "[SLASupportGeneration]") {
+    sla::PadConfig padcfg;
+
+    // Add some wings to the pad to test the cavity
+    padcfg.wall_height_mm = 1.;
+    padcfg.embed_object.enabled = true;
+    padcfg.embed_object.everywhere = true;
+
+    for (auto &fname : AROUND_PAD_TEST_OBJECTS) test_pad(fname, padcfg);
+}
+
+TEST_CASE("ElevatedSupportGeometryIsValid", "[SLASupportGeneration]") {
+    sla::SupportConfig supportcfg;
+    supportcfg.object_elevation_mm = 5.;
+
+    for (auto fname : SUPPORT_TEST_MODELS) test_supports(fname);
+}
+
+TEST_CASE("FloorSupportGeometryIsValid", "[SLASupportGeneration]") {
+    sla::SupportConfig supportcfg;
+    supportcfg.object_elevation_mm = 0;
+
+    for (auto &fname: SUPPORT_TEST_MODELS) test_supports(fname, supportcfg);
+}
+
+TEST_CASE("ElevatedSupportsDoNotPierceModel", "[SLASupportGeneration]") {
+
+    sla::SupportConfig supportcfg;
+
+    for (auto fname : SUPPORT_TEST_MODELS)
+        test_support_model_collision(fname, supportcfg);
+}
+
+TEST_CASE("FloorSupportsDoNotPierceModel", "[SLASupportGeneration]") {
+
+    sla::SupportConfig supportcfg;
+    supportcfg.object_elevation_mm = 0;
+
+    for (auto fname : SUPPORT_TEST_MODELS)
+        test_support_model_collision(fname, supportcfg);
+}
+
+TEST_CASE("DefaultRasterShouldBeEmpty", "[SLARasterOutput]") {
+    sla::Raster raster;
+    REQUIRE(raster.empty());
+}
+
+TEST_CASE("InitializedRasterShouldBeNONEmpty", "[SLARasterOutput]") {
+    // Default Prusa SL1 display parameters
+    sla::Raster::Resolution res{2560, 1440};
+    sla::Raster::PixelDim   pixdim{120. / res.width_px, 68. / res.height_px};
+
+    sla::Raster raster;
+    raster.reset(res, pixdim);
+    REQUIRE_FALSE(raster.empty());
+    REQUIRE(raster.resolution().width_px == res.width_px);
+    REQUIRE(raster.resolution().height_px == res.height_px);
+    REQUIRE(raster.pixel_dimensions().w_mm == Approx(pixdim.w_mm));
+    REQUIRE(raster.pixel_dimensions().h_mm == Approx(pixdim.h_mm));
+}
+
+using TPixel = uint8_t;
+static constexpr const TPixel FullWhite = 255;
+static constexpr const TPixel FullBlack = 0;
+
+template <class A, int N> constexpr int arraysize(const A (&)[N]) { return N; }
+
+static void check_raster_transformations(sla::Raster::Orientation o,
+                                         sla::Raster::TMirroring  mirroring)
+{
+    double disp_w = 120., disp_h = 68.;
+    sla::Raster::Resolution res{2560, 1440};
+    sla::Raster::PixelDim pixdim{disp_w / res.width_px, disp_h / res.height_px};
+
+    auto bb = BoundingBox({0, 0}, {scaled(disp_w), scaled(disp_h)});
+    sla::Raster::Trafo trafo{o, mirroring};
+    trafo.origin_x = bb.center().x();
+    trafo.origin_y = bb.center().y();
+
+    sla::Raster raster{res, pixdim, trafo};
+
+    // create box of size 32x32 pixels (not 1x1 to avoid antialiasing errors)
+    coord_t pw = 32 * coord_t(std::ceil(scaled<double>(pixdim.w_mm)));
+    coord_t ph = 32 * coord_t(std::ceil(scaled<double>(pixdim.h_mm)));
+    ExPolygon box;
+    box.contour.points = {{-pw, -ph}, {pw, -ph}, {pw, ph}, {-pw, ph}};
+
+    double tr_x = scaled<double>(20.), tr_y = tr_x;
+
+    box.translate(tr_x, tr_y);
+    ExPolygon expected_box = box;
+
+    // Now calculate the position of the translated box according to output
+    // trafo.
+    if (o == sla::Raster::Orientation::roPortrait) expected_box.rotate(PI / 2.);
+
+    if (mirroring[X])
+        for (auto &p : expected_box.contour.points) p.x() = -p.x();
+
+    if (mirroring[Y])
+        for (auto &p : expected_box.contour.points) p.y() = -p.y();
+
+    raster.draw(box);
+
+    Point expected_coords = expected_box.contour.bounding_box().center();
+    double rx = unscaled(expected_coords.x() + bb.center().x()) / pixdim.w_mm;
+    double ry = unscaled(expected_coords.y() + bb.center().y()) / pixdim.h_mm;
+    auto w = size_t(std::floor(rx));
+    auto h = res.height_px - size_t(std::floor(ry));
+
+    REQUIRE((w < res.width_px && h < res.height_px));
+
+    auto px = raster.read_pixel(w, h);
+
+    if (px != FullWhite) {
+        sla::PNGImage img;
+        std::fstream outf("out.png", std::ios::out);
+
+        outf << img.serialize(raster);
+    }
+
+    REQUIRE(px == FullWhite);
+}
+
+TEST_CASE("MirroringShouldBeCorrect", "[SLARasterOutput]") {
+    sla::Raster::TMirroring mirrorings[] = {sla::Raster::NoMirror,
+                                            sla::Raster::MirrorX,
+                                            sla::Raster::MirrorY,
+                                            sla::Raster::MirrorXY};
+
+    sla::Raster::Orientation orientations[] = {sla::Raster::roLandscape,
+                                               sla::Raster::roPortrait};
+    for (auto orientation : orientations)
+        for (auto &mirror : mirrorings)
+            check_raster_transformations(orientation, mirror);
+}
+
+static ExPolygon square_with_hole(double v)
+{
+    ExPolygon poly;
+    coord_t V = scaled(v / 2.);
+
+    poly.contour.points = {{-V, -V}, {V, -V}, {V, V}, {-V, V}};
+    poly.holes.emplace_back();
+    V = V / 2;
+    poly.holes.front().points = {{-V, V}, {V, V}, {V, -V}, {-V, -V}};
+    return poly;
+}
+
+static double pixel_area(TPixel px, const sla::Raster::PixelDim &pxdim)
+{
+    return (pxdim.h_mm * pxdim.w_mm) * px * 1. / (FullWhite - FullBlack);
+}
+
+static double raster_white_area(const sla::Raster &raster)
+{
+    if (raster.empty()) return std::nan("");
+
+    auto res = raster.resolution();
+    double a = 0;
+
+    for (size_t x = 0; x < res.width_px; ++x)
+        for (size_t y = 0; y < res.height_px; ++y) {
+            auto px = raster.read_pixel(x, y);
+            a += pixel_area(px, raster.pixel_dimensions());
+        }
+
+    return a;
+}
+
+static double predict_error(const ExPolygon &p, const sla::Raster::PixelDim &pd)
+{
+    auto lines = p.lines();
+    double pix_err = pixel_area(FullWhite, pd)  / 2.;
+
+    // Worst case is when a line is parallel to the shorter axis of one pixel,
+    // when the line will be composed of the max number of pixels
+    double pix_l = std::min(pd.h_mm, pd.w_mm);
+
+    double error = 0.;
+    for (auto &l : lines)
+        error += (unscaled(l.length()) / pix_l) * pix_err;
+
+    return error;
+}
+
+TEST_CASE("RasterizedPolygonAreaShouldMatch", "[SLARasterOutput]") {
+    double disp_w = 120., disp_h = 68.;
+    sla::Raster::Resolution res{2560, 1440};
+    sla::Raster::PixelDim pixdim{disp_w / res.width_px, disp_h / res.height_px};
+
+    sla::Raster raster{res, pixdim};
+    auto bb = BoundingBox({0, 0}, {scaled(disp_w), scaled(disp_h)});
+
+    ExPolygon poly = square_with_hole(10.);
+    poly.translate(bb.center().x(), bb.center().y());
+    raster.draw(poly);
+
+    double a = poly.area() / (scaled<double>(1.) * scaled(1.));
+    double ra = raster_white_area(raster);
+    double diff = std::abs(a - ra);
+
+    REQUIRE(diff <= predict_error(poly, pixdim));
+
+    raster.clear();
+    poly = square_with_hole(60.);
+    poly.translate(bb.center().x(), bb.center().y());
+    raster.draw(poly);
+
+    a = poly.area() / (scaled<double>(1.) * scaled(1.));
+    ra = raster_white_area(raster);
+    diff = std::abs(a - ra);
+
+    REQUIRE(diff <= predict_error(poly, pixdim));
+}