collision_test.cpp

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// MIT License

// Copyright (c) 2020 Erin Catto

// 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 "box2d/box2d.h"
#include "doctest.h"
#include <stdio.h>

// Unit tests for collision algorithms
DOCTEST_TEST_CASE("collision test")
{
        SUBCASE("polygon mass data")
        {
                const b2Vec2 center(100.0f, -50.0f);
                const float hx = 0.5f, hy = 1.5f;
                const float angle1 = 0.25f;

                // Data from issue #422. Not used because the data exceeds accuracy limits.
                //const b2Vec2 center(-15000.0f, -15000.0f);
                //const float hx = 0.72f, hy = 0.72f;
                //const float angle1 = 0.0f;

                b2PolygonShape polygon1;
                polygon1.SetAsBox(hx, hy, center, angle1);

                const float absTol = 2.0f * b2_epsilon;
                const float relTol = 2.0f * b2_epsilon;

                CHECK(b2Abs(polygon1.m_centroid.x - center.x) < absTol + relTol * b2Abs(center.x));
                CHECK(b2Abs(polygon1.m_centroid.y - center.y) < absTol + relTol * b2Abs(center.y));

                b2Vec2 vertices[4];
                vertices[0].Set(center.x - hx, center.y - hy);
                vertices[1].Set(center.x + hx, center.y - hy);
                vertices[2].Set(center.x - hx, center.y + hy);
                vertices[3].Set(center.x + hx, center.y + hy);

                b2PolygonShape polygon2;
                polygon2.Set(vertices, 4);

                CHECK(b2Abs(polygon2.m_centroid.x - center.x) < absTol + relTol * b2Abs(center.x));
                CHECK(b2Abs(polygon2.m_centroid.y - center.y) < absTol + relTol * b2Abs(center.y));

                const float mass = 4.0f * hx * hy;
                const float inertia = (mass / 3.0f) * (hx * hx + hy * hy) + mass * b2Dot(center, center);

                b2MassData massData1;
                polygon1.ComputeMass(&massData1, 1.0f);

                CHECK(b2Abs(massData1.center.x - center.x) < absTol + relTol * b2Abs(center.x));
                CHECK(b2Abs(massData1.center.y - center.y) < absTol + relTol * b2Abs(center.y));
                CHECK(b2Abs(massData1.mass - mass) < 20.0f * (absTol + relTol * mass));
                CHECK(b2Abs(massData1.I - inertia) < 40.0f * (absTol + relTol * inertia));

                b2MassData massData2;
                polygon2.ComputeMass(&massData2, 1.0f);

                CHECK(b2Abs(massData2.center.x - center.x) < absTol + relTol * b2Abs(center.x));
                CHECK(b2Abs(massData2.center.y - center.y) < absTol + relTol * b2Abs(center.y));
                CHECK(b2Abs(massData2.mass - mass) < 20.0f * (absTol + relTol * mass));
                CHECK(b2Abs(massData2.I - inertia) < 40.0f * (absTol + relTol * inertia));
        }
}