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Diffstat (limited to 'Client/ThirdParty/Box2D/testbed/tests/wrecking_ball.cpp')
-rw-r--r-- | Client/ThirdParty/Box2D/testbed/tests/wrecking_ball.cpp | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/Client/ThirdParty/Box2D/testbed/tests/wrecking_ball.cpp b/Client/ThirdParty/Box2D/testbed/tests/wrecking_ball.cpp new file mode 100644 index 0000000..74a61b4 --- /dev/null +++ b/Client/ThirdParty/Box2D/testbed/tests/wrecking_ball.cpp @@ -0,0 +1,165 @@ +// 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 test shows how a distance joint can be used to stabilize a chain of +/// bodies with a heavy payload. Notice that the distance joint just prevents +/// excessive stretching and has no other effect. +/// By disabling the distance joint you can see that the Box2D solver has trouble +/// supporting heavy bodies with light bodies. Try playing around with the +/// densities, time step, and iterations to see how they affect stability. +/// This test also shows how to use contact filtering. Filtering is configured +/// so that the payload does not collide with the chain. +class WreckingBall : public Test +{ +public: + WreckingBall() + { + b2Body* ground = NULL; + { + b2BodyDef bd; + ground = m_world->CreateBody(&bd); + + b2EdgeShape shape; + shape.SetTwoSided(b2Vec2(-40.0f, 0.0f), b2Vec2(40.0f, 0.0f)); + ground->CreateFixture(&shape, 0.0f); + } + + { + b2PolygonShape shape; + shape.SetAsBox(0.5f, 0.125f); + + b2FixtureDef fd; + fd.shape = &shape; + fd.density = 20.0f; + fd.friction = 0.2f; + fd.filter.categoryBits = 0x0001; + fd.filter.maskBits = 0xFFFF & ~0x0002; + + b2RevoluteJointDef jd; + jd.collideConnected = false; + + const int32 N = 10; + const float y = 15.0f; + m_distanceJointDef.localAnchorA.Set(0.0f, y); + + b2Body* prevBody = ground; + for (int32 i = 0; i < N; ++i) + { + b2BodyDef bd; + bd.type = b2_dynamicBody; + bd.position.Set(0.5f + 1.0f * i, y); + if (i == N - 1) + { + bd.position.Set(1.0f * i, y); + bd.angularDamping = 0.4f; + } + + b2Body* body = m_world->CreateBody(&bd); + + if (i == N - 1) + { + b2CircleShape circleShape; + circleShape.m_radius = 1.5f; + b2FixtureDef sfd; + sfd.shape = &circleShape; + sfd.density = 100.0f; + sfd.filter.categoryBits = 0x0002; + body->CreateFixture(&sfd); + } + else + { + body->CreateFixture(&fd); + } + + b2Vec2 anchor(float(i), y); + jd.Initialize(prevBody, body, anchor); + m_world->CreateJoint(&jd); + + prevBody = body; + } + + m_distanceJointDef.localAnchorB.SetZero(); + + float extraLength = 0.01f; + m_distanceJointDef.minLength = 0.0f; + m_distanceJointDef.maxLength = N - 1.0f + extraLength; + m_distanceJointDef.bodyB = prevBody; + } + + { + m_distanceJointDef.bodyA = ground; + m_distanceJoint = m_world->CreateJoint(&m_distanceJointDef); + m_stabilize = true; + } + } + + void UpdateUI() override + { + ImGui::SetNextWindowPos(ImVec2(10.0f, 100.0f)); + ImGui::SetNextWindowSize(ImVec2(200.0f, 100.0f)); + ImGui::Begin("Wrecking Ball Controls", nullptr, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoResize); + + if (ImGui::Checkbox("Stabilize", &m_stabilize)) + { + if (m_stabilize == true && m_distanceJoint == nullptr) + { + m_distanceJoint = m_world->CreateJoint(&m_distanceJointDef); + } + else if (m_stabilize == false && m_distanceJoint != nullptr) + { + m_world->DestroyJoint(m_distanceJoint); + m_distanceJoint = nullptr; + } + } + + ImGui::End(); + } + + void Step(Settings& settings) override + { + Test::Step(settings); + + if (m_distanceJoint) + { + g_debugDraw.DrawString(5, m_textLine, "Distance Joint ON"); + } + else + { + g_debugDraw.DrawString(5, m_textLine, "Distance Joint OFF"); + } + m_textLine += m_textIncrement; + } + + static Test* Create() + { + return new WreckingBall; + } + + b2DistanceJointDef m_distanceJointDef; + b2Joint* m_distanceJoint; + bool m_stabilize; +}; + +static int testIndex = RegisterTest("Examples", "Wrecking Ball", WreckingBall::Create); |