polygon_shapes.cpp

Go to the documentation of this file.

// 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 "test.h"


class PolygonShapesCallback : public b2QueryCallback
{
public:
        
        enum
        {
                e_maxCount = 4
        };

        PolygonShapesCallback()
        {
                m_count = 0;
        }

        bool ReportFixture(b2Fixture* fixture) override
        {
                if (m_count == e_maxCount)
                {
                        return false;
                }

                b2Body* body = fixture->GetBody();
                b2Shape* shape = fixture->GetShape();

                bool overlap = b2TestOverlap(shape, 0, &m_circle, 0, body->GetTransform(), m_transform);
                        
                if (overlap)
                {
                        b2Color color(0.95f, 0.95f, 0.6f);
                        b2Vec2 center = body->GetWorldCenter();
                        g_debugDraw->DrawPoint(center, 5.0f, color);
                        ++m_count;
                }

                return true;
        }

        b2CircleShape m_circle;
        b2Transform m_transform;
        b2Draw* g_debugDraw;
        int32 m_count;
};

class PolygonShapes : public Test
{
public:

        enum
        {
                e_maxBodies = 256
        };

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

                        b2EdgeShape shape;
                        shape.SetTwoSided(b2Vec2(-40.0f, 0.0f), b2Vec2(40.0f, 0.0f));
                        ground->CreateFixture(&shape, 0.0f);
                }

                {
                        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));
        }

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

                b2BodyDef bd;
                bd.type = b2_dynamicBody;

                float x = RandomFloat(-2.0f, 2.0f);
                bd.position.Set(x, 10.0f);
                bd.angle = RandomFloat(-b2_pi, b2_pi);

                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.density = 1.0f;
                        fd.friction = 0.3f;
                        m_bodies[m_bodyIndex]->CreateFixture(&fd);
                }
                else
                {
                        b2FixtureDef fd;
                        fd.shape = &m_circle;
                        fd.density = 1.0f;
                        fd.friction = 0.3f;

                        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_A:
                        for (int32 i = 0; i < e_maxBodies; i += 2)
                        {
                                if (m_bodies[i])
                                {
                                        bool enabled = m_bodies[i]->IsEnabled();
                                        m_bodies[i]->SetEnabled(!enabled);
                                }
                        }
                        break;

                case GLFW_KEY_D:
                        DestroyBody();
                        break;
                }
        }

        void Step(Settings& settings) override
        {
                Test::Step(settings);

                PolygonShapesCallback callback;
                callback.m_circle.m_radius = 2.0f;
                callback.m_circle.m_p.Set(0.0f, 1.1f);
                callback.m_transform.SetIdentity();
                callback.g_debugDraw = &g_debugDraw;

                b2AABB aabb;
                callback.m_circle.ComputeAABB(&aabb, callback.m_transform, 0);

                m_world->QueryAABB(&callback, aabb);

                b2Color color(0.4f, 0.7f, 0.8f);
                g_debugDraw.DrawCircle(callback.m_circle.m_p, callback.m_circle.m_radius, color);

                g_debugDraw.DrawString(5, m_textLine, "Press 1-5 to drop stuff, maximum of %d overlaps detected", PolygonShapesCallback::e_maxCount);
                m_textLine += m_textIncrement;
                g_debugDraw.DrawString(5, m_textLine, "Press 'a' to enable/disable some bodies");
                m_textLine += m_textIncrement;
                g_debugDraw.DrawString(5, m_textLine, "Press 'd' to destroy a body");
                m_textLine += m_textIncrement;
        }

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

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

static int testIndex = RegisterTest("Geometry", "Polygon Shapes", PolygonShapes::Create);