// 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" #include "imgui/imgui.h" // This shows how to use sensor shapes. Sensors don't have collision, but report overlap events. class Sensors : public Test { public: enum { e_count = 7 }; Sensors() { { 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); } #if 0 { b2FixtureDef sd; sd.SetAsBox(10.0f, 2.0f, b2Vec2(0.0f, 20.0f), 0.0f); sd.isSensor = true; m_sensor = ground->CreateFixture(&sd); } #else { b2CircleShape shape; shape.m_radius = 5.0f; shape.m_p.Set(0.0f, 10.0f); b2FixtureDef fd; fd.shape = &shape; fd.isSensor = true; m_sensor = ground->CreateFixture(&fd); } #endif } { b2CircleShape shape; shape.m_radius = 1.0f; for (int32 i = 0; i < e_count; ++i) { b2BodyDef bd; bd.type = b2_dynamicBody; bd.position.Set(-10.0f + 3.0f * i, 20.0f); bd.userData.pointer = i; m_touching[i] = false; m_bodies[i] = m_world->CreateBody(&bd); m_bodies[i]->CreateFixture(&shape, 1.0f); } } m_force = 100.0f; } // Implement contact listener. void BeginContact(b2Contact* contact) override { b2Fixture* fixtureA = contact->GetFixtureA(); b2Fixture* fixtureB = contact->GetFixtureB(); if (fixtureA == m_sensor) { uintptr_t index = fixtureB->GetBody()->GetUserData().pointer; if (index < e_count) { m_touching[index] = true; } } if (fixtureB == m_sensor) { uintptr_t index = fixtureA->GetBody()->GetUserData().pointer; if (index < e_count) { m_touching[index] = true; } } } // Implement contact listener. void EndContact(b2Contact* contact) override { b2Fixture* fixtureA = contact->GetFixtureA(); b2Fixture* fixtureB = contact->GetFixtureB(); if (fixtureA == m_sensor) { uintptr_t index = fixtureB->GetBody()->GetUserData().pointer; if (index < e_count) { m_touching[index] = false; } } if (fixtureB == m_sensor) { uintptr_t index = fixtureA->GetBody()->GetUserData().pointer; if (index < e_count) { m_touching[index] = false; } } } void UpdateUI() override { ImGui::SetNextWindowPos(ImVec2(10.0f, 100.0f)); ImGui::SetNextWindowSize(ImVec2(200.0f, 60.0f)); ImGui::Begin("Sensor Controls", nullptr, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoResize); ImGui::SliderFloat("Force", &m_force, 0.0f, 2000.0f, "%.0f"); ImGui::End(); } void Step(Settings& settings) override { Test::Step(settings); // Traverse the contact results. Apply a force on shapes // that overlap the sensor. for (int32 i = 0; i < e_count; ++i) { if (m_touching[i] == false) { continue; } b2Body* body = m_bodies[i]; b2Body* ground = m_sensor->GetBody(); b2CircleShape* circle = (b2CircleShape*)m_sensor->GetShape(); b2Vec2 center = ground->GetWorldPoint(circle->m_p); b2Vec2 position = body->GetPosition(); b2Vec2 d = center - position; if (d.LengthSquared() < FLT_EPSILON * FLT_EPSILON) { continue; } d.Normalize(); b2Vec2 F = m_force * d; body->ApplyForce(F, position, false); } } static Test* Create() { return new Sensors; } b2Fixture* m_sensor; b2Body* m_bodies[e_count]; float m_force; bool m_touching[e_count]; }; static int testIndex = RegisterTest("Collision", "Sensors", Sensors::Create);