RmlUi/Tests/Source/UnitTests/Math.cpp

/*
 * This source file is part of RmlUi, the HTML/CSS Interface Middleware
 *
 * For the latest information, see http://github.com/mikke89/RmlUi
 *
 * Copyright (c) 2008-2010 CodePoint Ltd, Shift Technology Ltd
 * Copyright (c) 2019 The RmlUi Team, and contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 */

#include <RmlUi/Core/Math.h>
#include <RmlUi/Core/Types.h>
#include <doctest.h>

using namespace Rml;

TEST_CASE("Math")
{
	const Colourb c0(0, 0, 0, 255);
	const Colourb c1(255, 0, 0, 255);
	const Colourb c2(127, 0, 0, 255);

	Colourb c;

	c = Math::RoundedLerp(0.0f, c0, c1);
	REQUIRE(c.red == c0.red);

	c = Math::RoundedLerp(179.f / 255.f, c0, c1);
	REQUIRE(c.red == 179);

	c = Math::RoundedLerp(50.4f / 255.f, c0, c1);
	REQUIRE(c.red == 50);

	c = Math::RoundedLerp(50.6f / 255.f, c0, c1);
	REQUIRE(c.red == 51);

	c = Math::RoundedLerp(0.0f, c1, c0);
	REQUIRE(c.red == c1.red);

	c = Math::RoundedLerp(1.0f, c0, c1);
	REQUIRE(c.red == c1.red);

	c = Math::RoundedLerp(1.0f, c1, c0);
	REQUIRE(c.red == c0.red);

	c = Math::RoundedLerp(1.0f, c0, c2);
	REQUIRE(c.red == c2.red);

	c = Math::RoundedLerp(0.0f, c2, c1);
	REQUIRE(c.red == c2.red);

	// Full-range interpolation
	for (int i = 0; i <= 255; i++)
	{
		const float t = float(i) / 255.f;
		const auto r = Math::RoundedLerp(t, c0, c1).red;
		REQUIRE(r == i);
	}

	// Reverse full-range interpolation
	for (int i = 0; i <= 255; i++)
	{
		const float t = float(i) / 255.f;
		const auto r = Math::RoundedLerp(t, c1, c0).red;
		REQUIRE(r == 255 - i);
	}

	// Half-range interpolation
	for (int i = 0; i <= 255; i++)
	{
		const float t = float(i) / 255.f;
		const auto r = Math::RoundedLerp(t, c0, c2).red;
		REQUIRE(r == i / 2);
	}

	// Same-color interpolation with fractional t
	for (int i = 0; i <= 379; i++)
	{
		const float t = float(i) / 379.f;
		const auto r0 = Math::RoundedLerp(t, c0, c0).red;
		const auto r1 = Math::RoundedLerp(t, c1, c1).red;
		const auto r2 = Math::RoundedLerp(t, c2, c2).red;
		REQUIRE(r0 == c0.red);
		REQUIRE(r1 == c1.red);
		REQUIRE(r2 == c2.red);
	}
}