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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 GearJoint : public Test
{
public:
GearJoint()
{
b2Body* ground = NULL;
{
b2BodyDef bd;
ground = m_world->CreateBody(&bd);
b2EdgeShape shape;
shape.SetTwoSided(b2Vec2(50.0f, 0.0f), b2Vec2(-50.0f, 0.0f));
ground->CreateFixture(&shape, 0.0f);
}
{
b2CircleShape circle1;
circle1.m_radius = 1.0f;
b2PolygonShape box;
box.SetAsBox(0.5f, 5.0f);
b2CircleShape circle2;
circle2.m_radius = 2.0f;
b2BodyDef bd1;
bd1.type = b2_staticBody;
bd1.position.Set(10.0f, 9.0f);
b2Body* body1 = m_world->CreateBody(&bd1);
body1->CreateFixture(&circle1, 5.0f);
b2BodyDef bd2;
bd2.type = b2_dynamicBody;
bd2.position.Set(10.0f, 8.0f);
b2Body* body2 = m_world->CreateBody(&bd2);
body2->CreateFixture(&box, 5.0f);
b2BodyDef bd3;
bd3.type = b2_dynamicBody;
bd3.position.Set(10.0f, 6.0f);
b2Body* body3 = m_world->CreateBody(&bd3);
body3->CreateFixture(&circle2, 5.0f);
b2RevoluteJointDef jd1;
jd1.Initialize(body1, body2, bd1.position);
b2Joint* joint1 = m_world->CreateJoint(&jd1);
b2RevoluteJointDef jd2;
jd2.Initialize(body2, body3, bd3.position);
b2Joint* joint2 = m_world->CreateJoint(&jd2);
b2GearJointDef jd4;
jd4.bodyA = body1;
jd4.bodyB = body3;
jd4.joint1 = joint1;
jd4.joint2 = joint2;
jd4.ratio = circle2.m_radius / circle1.m_radius;
m_world->CreateJoint(&jd4);
}
{
b2CircleShape circle1;
circle1.m_radius = 1.0f;
b2CircleShape circle2;
circle2.m_radius = 2.0f;
b2PolygonShape box;
box.SetAsBox(0.5f, 5.0f);
b2BodyDef bd1;
bd1.type = b2_dynamicBody;
bd1.position.Set(-3.0f, 12.0f);
b2Body* body1 = m_world->CreateBody(&bd1);
body1->CreateFixture(&circle1, 5.0f);
b2RevoluteJointDef jd1;
jd1.bodyA = ground;
jd1.bodyB = body1;
jd1.localAnchorA = ground->GetLocalPoint(bd1.position);
jd1.localAnchorB = body1->GetLocalPoint(bd1.position);
jd1.referenceAngle = body1->GetAngle() - ground->GetAngle();
m_joint1 = (b2RevoluteJoint*)m_world->CreateJoint(&jd1);
b2BodyDef bd2;
bd2.type = b2_dynamicBody;
bd2.position.Set(0.0f, 12.0f);
b2Body* body2 = m_world->CreateBody(&bd2);
body2->CreateFixture(&circle2, 5.0f);
b2RevoluteJointDef jd2;
jd2.Initialize(ground, body2, bd2.position);
m_joint2 = (b2RevoluteJoint*)m_world->CreateJoint(&jd2);
b2BodyDef bd3;
bd3.type = b2_dynamicBody;
bd3.position.Set(2.5f, 12.0f);
b2Body* body3 = m_world->CreateBody(&bd3);
body3->CreateFixture(&box, 5.0f);
b2PrismaticJointDef jd3;
jd3.Initialize(ground, body3, bd3.position, b2Vec2(0.0f, 1.0f));
jd3.lowerTranslation = -5.0f;
jd3.upperTranslation = 5.0f;
jd3.enableLimit = true;
m_joint3 = (b2PrismaticJoint*)m_world->CreateJoint(&jd3);
b2GearJointDef jd4;
jd4.bodyA = body1;
jd4.bodyB = body2;
jd4.joint1 = m_joint1;
jd4.joint2 = m_joint2;
jd4.ratio = circle2.m_radius / circle1.m_radius;
m_joint4 = (b2GearJoint*)m_world->CreateJoint(&jd4);
b2GearJointDef jd5;
jd5.bodyA = body2;
jd5.bodyB = body3;
jd5.joint1 = m_joint2;
jd5.joint2 = m_joint3;
jd5.ratio = -1.0f / circle2.m_radius;
m_joint5 = (b2GearJoint*)m_world->CreateJoint(&jd5);
}
}
void Step(Settings& settings) override
{
Test::Step(settings);
float ratio, value;
ratio = m_joint4->GetRatio();
value = m_joint1->GetJointAngle() + ratio * m_joint2->GetJointAngle();
g_debugDraw.DrawString(5, m_textLine, "theta1 + %4.2f * theta2 = %4.2f", (float) ratio, (float) value);
m_textLine += m_textIncrement;
ratio = m_joint5->GetRatio();
value = m_joint2->GetJointAngle() + ratio * m_joint3->GetJointTranslation();
g_debugDraw.DrawString(5, m_textLine, "theta2 + %4.2f * delta = %4.2f", (float) ratio, (float) value);
m_textLine += m_textIncrement;
}
static Test* Create()
{
return new GearJoint;
}
b2RevoluteJoint* m_joint1;
b2RevoluteJoint* m_joint2;
b2PrismaticJoint* m_joint3;
b2GearJoint* m_joint4;
b2GearJoint* m_joint5;
};
static int testIndex = RegisterTest("Joints", "Gear", GearJoint::Create);
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