godot/tests/test_gradient.h

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/*  test_gradient.h                                                      */
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#ifndef TEST_GRADIENT_H
#define TEST_GRADIENT_H

#include "core/class_db.h"
#include "core/color.h"
#include "scene/resources/gradient.h"

#include "thirdparty/doctest/doctest.h"

namespace TestGradient {

TEST_CASE("[Gradient] Default gradient") {
	// Black-white gradient.
	Ref<Gradient> gradient = memnew(Gradient);

	CHECK_MESSAGE(
			gradient->get_points_count() == 2,
			"Default gradient should contain the expected number of points.");

	CHECK_MESSAGE(
			gradient->get_color_at_offset(0.0).is_equal_approx(Color(0, 0, 0)),
			"Default gradient should return the expected interpolated value at offset 0.0.");
	CHECK_MESSAGE(
			gradient->get_color_at_offset(0.4).is_equal_approx(Color(0.4, 0.4, 0.4)),
			"Default gradient should return the expected interpolated value at offset 0.4.");
	CHECK_MESSAGE(
			gradient->get_color_at_offset(0.8).is_equal_approx(Color(0.8, 0.8, 0.8)),
			"Default gradient should return the expected interpolated value at offset 0.8.");
	CHECK_MESSAGE(
			gradient->get_color_at_offset(1.0).is_equal_approx(Color(1, 1, 1)),
			"Default gradient should return the expected interpolated value at offset 1.0.");

	// Out of bounds checks.
	CHECK_MESSAGE(
			gradient->get_color_at_offset(-1.0).is_equal_approx(Color(0, 0, 0)),
			"Default gradient should return the expected interpolated value at offset -1.0.");
	CHECK_MESSAGE(
			gradient->get_color_at_offset(1234.0).is_equal_approx(Color(1, 1, 1)),
			"Default gradient should return the expected interpolated value at offset 1234.0.");
}

TEST_CASE("[Gradient] Custom gradient (points specified in order)") {
	// Red-yellow-green gradient (with overbright green).
	Ref<Gradient> gradient = memnew(Gradient);
	Vector<Gradient::Point> points;
	points.push_back({ 0.0, Color(1, 0, 0) });
	points.push_back({ 0.5, Color(1, 1, 0) });
	points.push_back({ 1.0, Color(0, 2, 0) });
	gradient->set_points(points);

	CHECK_MESSAGE(
			gradient->get_points_count() == 3,
			"Custom gradient should contain the expected number of points.");

	CHECK_MESSAGE(
			gradient->get_color_at_offset(0.0).is_equal_approx(Color(1, 0, 0)),
			"Custom gradient should return the expected interpolated value at offset 0.0.");
	CHECK_MESSAGE(
			gradient->get_color_at_offset(0.25).is_equal_approx(Color(1, 0.5, 0)),
			"Custom gradient should return the expected interpolated value at offset 0.25.");
	CHECK_MESSAGE(
			gradient->get_color_at_offset(0.5).is_equal_approx(Color(1, 1, 0)),
			"Custom gradient should return the expected interpolated value at offset 0.5.");
	CHECK_MESSAGE(
			gradient->get_color_at_offset(0.75).is_equal_approx(Color(0.5, 1.5, 0)),
			"Custom gradient should return the expected interpolated value at offset 0.75.");
	CHECK_MESSAGE(
			gradient->get_color_at_offset(1.0).is_equal_approx(Color(0, 2, 0)),
			"Custom gradient should return the expected interpolated value at offset 1.0.");

	gradient->remove_point(1);
	CHECK_MESSAGE(
			gradient->get_points_count() == 2,
			"Custom gradient should contain the expected number of points after removing one point.");
	CHECK_MESSAGE(
			gradient->get_color_at_offset(0.5).is_equal_approx(Color(0.5, 1, 0)),
			"Custom gradient should return the expected interpolated value at offset 0.5 after removing point at index 1.");
}

TEST_CASE("[Gradient] Custom gradient (points specified out-of-order)") {
	// HSL rainbow with points specified out of order.
	// These should be sorted automatically when adding points.
	Ref<Gradient> gradient = memnew(Gradient);
	Vector<Gradient::Point> points;
	points.push_back({ 0.2, Color(1, 0, 0) });
	points.push_back({ 0.0, Color(1, 1, 0) });
	points.push_back({ 0.8, Color(0, 1, 0) });
	points.push_back({ 0.4, Color(0, 1, 1) });
	points.push_back({ 1.0, Color(0, 0, 1) });
	points.push_back({ 0.6, Color(1, 0, 1) });
	gradient->set_points(points);

	CHECK_MESSAGE(
			gradient->get_points_count() == 6,
			"Custom out-of-order gradient should contain the expected number of points.");

	CHECK_MESSAGE(
			gradient->get_color_at_offset(0.0).is_equal_approx(Color(1, 1, 0)),
			"Custom out-of-order gradient should return the expected interpolated value at offset 0.0.");
	CHECK_MESSAGE(
			gradient->get_color_at_offset(0.3).is_equal_approx(Color(0.5, 0.5, 0.5)),
			"Custom out-of-order gradient should return the expected interpolated value at offset 0.3.");
	CHECK_MESSAGE(
			gradient->get_color_at_offset(0.6).is_equal_approx(Color(1, 0, 1)),
			"Custom out-of-order gradient should return the expected interpolated value at offset 0.6.");
	CHECK_MESSAGE(
			gradient->get_color_at_offset(1.0).is_equal_approx(Color(0, 0, 1)),
			"Custom out-of-order gradient should return the expected interpolated value at offset 1.0.");

	gradient->remove_point(0);
	CHECK_MESSAGE(
			gradient->get_points_count() == 5,
			"Custom out-of-order gradient should contain the expected number of points after removing one point.");
	// The color will be clamped to the nearest point (which is at offset 0.2).
	CHECK_MESSAGE(
			gradient->get_color_at_offset(0.1).is_equal_approx(Color(1, 0, 0)),
			"Custom out-of-order gradient should return the expected interpolated value at offset 0.1 after removing point at index 0.");
}

} // namespace TestGradient

#endif // TEST_GRADIENT_H