edge_shapes.cpp

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// MIT License

// Copyright (c) 2019 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 "settings.h"
#include "test.h"

class EdgeShapesCallback : public b2RayCastCallback
{
public:
        EdgeShapesCallback()
        {
                m_fixture = NULL;
        }

        float ReportFixture(b2Fixture* fixture, const b2Vec2& point,
                                                  const b2Vec2& normal, float fraction) override
        {
                m_fixture = fixture;
                m_point = point;
                m_normal = normal;

                return fraction;
        }

        b2Fixture* m_fixture;
        b2Vec2 m_point;
        b2Vec2 m_normal;
};

class EdgeShapes : public Test
{
public:

        enum
        {
                e_maxBodies = 256
        };

        EdgeShapes()
        {
                // Ground body
                {
                        b2BodyDef bd;
                        b2Body* ground = m_world->CreateBody(&bd);

                        float x1 = -20.0f;
                        float y1 = 2.0f * cosf(x1 / 10.0f * b2_pi);
                        for (int32 i = 0; i < 80; ++i)
                        {
                                float x2 = x1 + 0.5f;
                                float y2 = 2.0f * cosf(x2 / 10.0f * b2_pi);

                                b2EdgeShape shape;
                                shape.SetTwoSided(b2Vec2(x1, y1), b2Vec2(x2, y2));
                                ground->CreateFixture(&shape, 0.0f);

                                x1 = x2;
                                y1 = y2;
                        }
                }

                {
                b2Vec2 vertices[3];
                vertices[0].Set(-0.5f, 0.0f);
                vertices[1].Set(0.5f, 0.0f);
                vertices[2].Set(0.0f, 1.5f);
                m_polygons[0].Set(vertices, 3);
        }

                {
                        b2Vec2 vertices[3];
                        vertices[0].Set(-0.1f, 0.0f);
                        vertices[1].Set(0.1f, 0.0f);
                        vertices[2].Set(0.0f, 1.5f);
                        m_polygons[1].Set(vertices, 3);
                }

                {
                        float w = 1.0f;
                        float b = w / (2.0f + b2Sqrt(2.0f));
                        float s = b2Sqrt(2.0f) * b;

                        b2Vec2 vertices[8];
                        vertices[0].Set(0.5f * s, 0.0f);
                        vertices[1].Set(0.5f * w, b);
                        vertices[2].Set(0.5f * w, b + s);
                        vertices[3].Set(0.5f * s, w);
                        vertices[4].Set(-0.5f * s, w);
                        vertices[5].Set(-0.5f * w, b + s);
                        vertices[6].Set(-0.5f * w, b);
                        vertices[7].Set(-0.5f * s, 0.0f);

                        m_polygons[2].Set(vertices, 8);
                }

                {
                        m_polygons[3].SetAsBox(0.5f, 0.5f);
                }

                {
                        m_circle.m_radius = 0.5f;
                }

                m_bodyIndex = 0;
                memset(m_bodies, 0, sizeof(m_bodies));

                m_angle = 0.0f;
        }

        void Create(int32 index)
        {
                if (m_bodies[m_bodyIndex] != NULL)
                {
                        m_world->DestroyBody(m_bodies[m_bodyIndex]);
                        m_bodies[m_bodyIndex] = NULL;
                }

                b2BodyDef bd;

                float x = RandomFloat(-10.0f, 10.0f);
                float y = RandomFloat(10.0f, 20.0f);
                bd.position.Set(x, y);
                bd.angle = RandomFloat(-b2_pi, b2_pi);
                bd.type = b2_dynamicBody;

                if (index == 4)
                {
                        bd.angularDamping = 0.02f;
                }

                m_bodies[m_bodyIndex] = m_world->CreateBody(&bd);

                if (index < 4)
                {
                        b2FixtureDef fd;
                        fd.shape = m_polygons + index;
                        fd.friction = 0.3f;
                        fd.density = 20.0f;
                        m_bodies[m_bodyIndex]->CreateFixture(&fd);
                }
                else
                {
                        b2FixtureDef fd;
                        fd.shape = &m_circle;
                        fd.friction = 0.3f;
                        fd.density = 20.0f;
                        m_bodies[m_bodyIndex]->CreateFixture(&fd);
                }

                m_bodyIndex = (m_bodyIndex + 1) % e_maxBodies;
        }

        void DestroyBody()
        {
                for (int32 i = 0; i < e_maxBodies; ++i)
                {
                        if (m_bodies[i] != NULL)
                        {
                                m_world->DestroyBody(m_bodies[i]);
                                m_bodies[i] = NULL;
                                return;
                        }
                }
        }

        void Keyboard(int key) override
        {
                switch (key)
                {
                case GLFW_KEY_1:
                case GLFW_KEY_2:
                case GLFW_KEY_3:
                case GLFW_KEY_4:
                case GLFW_KEY_5:
                        Create(key - GLFW_KEY_1);
                        break;

                case GLFW_KEY_D:
                        DestroyBody();
                        break;
                }
        }

        void Step(Settings& settings) override
        {
                bool advanceRay = settings.m_pause == 0 || settings.m_singleStep;

                Test::Step(settings);
                g_debugDraw.DrawString(5, m_textLine, "Press 1-5 to drop stuff");
                m_textLine += m_textIncrement;

                float L = 25.0f;
                b2Vec2 point1(0.0f, 10.0f);
                b2Vec2 d(L * cosf(m_angle), -L * b2Abs(sinf(m_angle)));
                b2Vec2 point2 = point1 + d;

                EdgeShapesCallback callback;

                m_world->RayCast(&callback, point1, point2);

                if (callback.m_fixture)
                {
                        g_debugDraw.DrawPoint(callback.m_point, 5.0f, b2Color(0.4f, 0.9f, 0.4f));

                        g_debugDraw.DrawSegment(point1, callback.m_point, b2Color(0.8f, 0.8f, 0.8f));

                        b2Vec2 head = callback.m_point + 0.5f * callback.m_normal;
                        g_debugDraw.DrawSegment(callback.m_point, head, b2Color(0.9f, 0.9f, 0.4f));
                }
                else
                {
                        g_debugDraw.DrawSegment(point1, point2, b2Color(0.8f, 0.8f, 0.8f));
                }

                if (advanceRay)
                {
                        m_angle += 0.25f * b2_pi / 180.0f;
                }
        }

        static Test* Create()
        {
                return new EdgeShapes;
        }

        int32 m_bodyIndex;
        b2Body* m_bodies[e_maxBodies];
        b2PolygonShape m_polygons[4];
        b2CircleShape m_circle;

        float m_angle;
};

static int testIndex = RegisterTest("Geometry", "Edge Shapes", EdgeShapes::Create);