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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"
/// This test shows how to use a motor joint. A motor joint
/// can be used to animate a dynamic body. With finite motor forces
/// the body can be blocked by collision with other bodies.
class MotorJoint : public Test
{
public:
MotorJoint()
{
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 motorized body
{
b2BodyDef bd;
bd.type = b2_dynamicBody;
bd.position.Set(0.0f, 8.0f);
b2Body* body = m_world->CreateBody(&bd);
b2PolygonShape shape;
shape.SetAsBox(2.0f, 0.5f);
b2FixtureDef fd;
fd.shape = &shape;
fd.friction = 0.6f;
fd.density = 2.0f;
body->CreateFixture(&fd);
b2MotorJointDef mjd;
mjd.Initialize(ground, body);
mjd.maxForce = 1000.0f;
mjd.maxTorque = 1000.0f;
m_joint = (b2MotorJoint*)m_world->CreateJoint(&mjd);
}
m_go = false;
m_time = 0.0f;
}
void Keyboard(int key) override
{
switch (key)
{
case GLFW_KEY_S:
m_go = !m_go;
break;
}
}
void Step(Settings& settings) override
{
if (m_go && settings.m_hertz > 0.0f)
{
m_time += 1.0f / settings.m_hertz;
}
b2Vec2 linearOffset;
linearOffset.x = 6.0f * sinf(2.0f * m_time);
linearOffset.y = 8.0f + 4.0f * sinf(1.0f * m_time);
float angularOffset = 4.0f * m_time;
m_joint->SetLinearOffset(linearOffset);
m_joint->SetAngularOffset(angularOffset);
g_debugDraw.DrawPoint(linearOffset, 4.0f, b2Color(0.9f, 0.9f, 0.9f));
Test::Step(settings);
g_debugDraw.DrawString(5, m_textLine, "Keys: (s) pause");
m_textLine += 15;
}
static Test* Create()
{
return new MotorJoint;
}
b2MotorJoint* m_joint;
float m_time;
bool m_go;
};
static int testIndex = RegisterTest("Joints", "Motor Joint", MotorJoint::Create);
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