1 files changed, 118 insertions, 0 deletions
diff --git a/tests/libslic3r/test_curve_fitting.cpp b/tests/libslic3r/test_curve_fitting.cpp
new file mode 100644
index 000000000..faf7839c7
--- /dev/null
+++ b/tests/libslic3r/test_curve_fitting.cpp
@@ -0,0 +1,118 @@
+#include <catch2/catch.hpp>
+#include <test_utils.hpp>
+
+#include <libslic3r/Geometry/Curves.hpp>
+#include <libslic3r/Utils.hpp>
+#include <libslic3r/SVG.hpp>
+
+TEST_CASE("Curves: cubic b spline fit test", "[Curves]") {
+    using namespace Slic3r;
+    using namespace Slic3r::Geometry;
+
+    auto fx = [&](size_t index) {
+        return float(index) / 200.0f;
+    };
+
+    auto fy = [&](size_t index) {
+        return 1.0f;
+    };
+
+    std::vector<Vec<1, float>> observations { };
+    std::vector<float> observation_points { };
+    std::vector<float> weights { };
+    for (size_t index = 0; index < 200; ++index) {
+        observations.push_back(Vec<1, float> { fy(index) });
+        observation_points.push_back(fx(index));
+        weights.push_back(1);
+    }
+
+    Vec2f fmin { fx(0), fy(0) };
+    Vec2f fmax { fx(200), fy(200) };
+
+    auto bspline = fit_cubic_bspline(observations, observation_points, weights, 1);
+
+    Approx ap(1.0f);
+    ap.epsilon(0.1f);
+
+    for (int p = 0; p < 200; ++p) {
+        float fitted_val = bspline.get_fitted_value(fx(p))(0);
+        float expected = fy(p);
+
+        REQUIRE(fitted_val == ap(expected));
+
+    }
+}
+
+TEST_CASE("Curves: quadratic f cubic b spline fit test", "[Curves]") {
+    using namespace Slic3r;
+    using namespace Slic3r::Geometry;
+
+    auto fx = [&](size_t index) {
+        return float(index) / 100.0f;
+    };
+
+    auto fy = [&](size_t index) {
+        return (fx(index) - 1) * (fx(index) - 1);
+    };
+
+    std::vector<Vec<1, float>> observations { };
+    std::vector<float> observation_points { };
+    std::vector<float> weights { };
+    for (size_t index = 0; index < 200; ++index) {
+        observations.push_back(Vec<1, float> { fy(index) });
+        observation_points.push_back(fx(index));
+        weights.push_back(1);
+    }
+
+    Vec2f fmin { fx(0), fy(0) };
+    Vec2f fmax { fx(200), fy(200) };
+
+    auto bspline = fit_cubic_bspline(observations, observation_points, weights, 10);
+
+    for (int p = 0; p < 200; ++p) {
+        float fitted_val = bspline.get_fitted_value(fx(p))(0);
+        float expected = fy(p);
+
+        auto check = [](float a, float b) {
+            return abs(a - b) < 0.2f;
+        };
+        //Note: checking is problematic, splines will not perfectly align
+        REQUIRE(check(fitted_val, expected));
+
+    }
+}
+
+TEST_CASE("Curves: polynomial fit test", "[Curves]") {
+    using namespace Slic3r;
+    using namespace Slic3r::Geometry;
+
+    auto fx = [&](size_t index) {
+        return float(index) / 100.0f;
+    };
+
+    auto fy = [&](size_t index) {
+        return (fx(index) - 1) * (fx(index) - 1);
+    };
+
+    std::vector<Vec<1, float>> observations { };
+    std::vector<float> observation_points { };
+    std::vector<float> weights { };
+    for (size_t index = 0; index < 200; ++index) {
+        observations.push_back(Vec<1, float> { fy(index) });
+        observation_points.push_back(fx(index));
+        weights.push_back(1);
+    }
+
+    Vec2f fmin { fx(0), fy(0) };
+    Vec2f fmax { fx(200), fy(200) };
+
+    Approx ap(1.0f);
+    ap.epsilon(0.1f);
+
+    auto poly = fit_polynomial(observations, observation_points, weights, 2);
+
+    REQUIRE(poly.coefficients(0, 0) == ap(1));
+    REQUIRE(poly.coefficients(0, 1) == ap(-2));
+    REQUIRE(poly.coefficients(0, 2) == ap(1));
+}
+