body_types.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 "test.h"
 
class BodyTypes : public Test
{
public:
        BodyTypes()
        {
                b2Body* ground = NULL;
                {
                        b2BodyDef bd;
                        ground = m_world->CreateBody(&bd);
 
                        b2EdgeShape shape;
                        shape.SetTwoSided(b2Vec2(-20.0f, 0.0f), b2Vec2(20.0f, 0.0f));
 
                        b2FixtureDef fd;
                        fd.shape = &shape;
 
                        ground->CreateFixture(&fd);
                }
 
                // Define attachment
                {
                        b2BodyDef bd;
                        bd.type = b2_dynamicBody;
                        bd.position.Set(0.0f, 3.0f);
                        m_attachment = m_world->CreateBody(&bd);
 
                        b2PolygonShape shape;
                        shape.SetAsBox(0.5f, 2.0f);
                        m_attachment->CreateFixture(&shape, 2.0f);
                }
 
                // Define platform
                {
                        b2BodyDef bd;
                        bd.type = b2_dynamicBody;
                        bd.position.Set(-4.0f, 5.0f);
                        m_platform = m_world->CreateBody(&bd);
 
                        b2PolygonShape shape;
                        shape.SetAsBox(0.5f, 4.0f, b2Vec2(4.0f, 0.0f), 0.5f * b2_pi);
 
                        b2FixtureDef fd;
                        fd.shape = &shape;
                        fd.friction = 0.6f;
                        fd.density = 2.0f;
                        m_platform->CreateFixture(&fd);
 
                        b2RevoluteJointDef rjd;
                        rjd.Initialize(m_attachment, m_platform, b2Vec2(0.0f, 5.0f));
                        rjd.maxMotorTorque = 50.0f;
                        rjd.enableMotor = true;
                        m_world->CreateJoint(&rjd);
 
                        b2PrismaticJointDef pjd;
                        pjd.Initialize(ground, m_platform, b2Vec2(0.0f, 5.0f), b2Vec2(1.0f, 0.0f));
 
                        pjd.maxMotorForce = 1000.0f;
                        pjd.enableMotor = true;
                        pjd.lowerTranslation = -10.0f;
                        pjd.upperTranslation = 10.0f;
                        pjd.enableLimit = true;
 
                        m_world->CreateJoint(&pjd);
 
                        m_speed = 3.0f;
                }
 
                // Create a payload
                {
                        b2BodyDef bd;
                        bd.type = b2_dynamicBody;
                        bd.position.Set(0.0f, 8.0f);
                        b2Body* body = m_world->CreateBody(&bd);
 
                        b2PolygonShape shape;
                        shape.SetAsBox(0.75f, 0.75f);
 
                        b2FixtureDef fd;
                        fd.shape = &shape;
                        fd.friction = 0.6f;
                        fd.density = 2.0f;
 
                        body->CreateFixture(&fd);
                }
        }
 
        void Keyboard(int key) override
        {
                switch (key)
                {
                case GLFW_KEY_D:
                        m_platform->SetType(b2_dynamicBody);
                        break;
 
                case GLFW_KEY_S:
                        m_platform->SetType(b2_staticBody);
                        break;
 
                case GLFW_KEY_K:
                        m_platform->SetType(b2_kinematicBody);
                        m_platform->SetLinearVelocity(b2Vec2(-m_speed, 0.0f));
                        m_platform->SetAngularVelocity(0.0f);
                        break;
                }
        }
 
        void Step(Settings& settings) override
        {
                // Drive the kinematic body.
                if (m_platform->GetType() == b2_kinematicBody)
                {
                        b2Vec2 p = m_platform->GetTransform().p;
                        b2Vec2 v = m_platform->GetLinearVelocity();
 
                        if ((p.x < -10.0f && v.x < 0.0f) ||
                                (p.x > 10.0f && v.x > 0.0f))
                        {
                                v.x = -v.x;
                                m_platform->SetLinearVelocity(v);
                        }
                }
 
                Test::Step(settings);
 
                g_debugDraw.DrawString(5, m_textLine, "Keys: (d) dynamic, (s) static, (k) kinematic");
                m_textLine += m_textIncrement;
        }
 
        static Test* Create()
        {
                return new BodyTypes;
        }
 
        b2Body* m_attachment;
        b2Body* m_platform;
        float m_speed;
};
 
static int testIndex = RegisterTest("Examples", "Body Types", BodyTypes::Create);