axmol/tests/cpp-tests/Classes/Box2DTestBed/tests/cantilever.cpp

219 lines
5.1 KiB
C++

// 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"
// It is difficult to make a cantilever made of links completely rigid with weld joints.
// You will have to use a high number of iterations to make them stiff.
// So why not go ahead and use soft weld joints? They behave like a revolute
// joint with a rotational spring.
class Cantilever : public Test
{
public:
enum
{
e_count = 8
};
Cantilever()
{
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;
b2WeldJointDef jd;
b2Body* prevBody = ground;
for (int32 i = 0; i < e_count; ++i)
{
b2BodyDef bd;
bd.type = b2_dynamicBody;
bd.position.Set(-14.5f + 1.0f * i, 5.0f);
b2Body* body = m_world->CreateBody(&bd);
body->CreateFixture(&fd);
b2Vec2 anchor(-15.0f + 1.0f * i, 5.0f);
jd.Initialize(prevBody, body, anchor);
m_world->CreateJoint(&jd);
prevBody = body;
}
}
{
b2PolygonShape shape;
shape.SetAsBox(1.0f, 0.125f);
b2FixtureDef fd;
fd.shape = &shape;
fd.density = 20.0f;
b2WeldJointDef jd;
float frequencyHz = 5.0f;
float dampingRatio = 0.7f;
b2Body* prevBody = ground;
for (int32 i = 0; i < 3; ++i)
{
b2BodyDef bd;
bd.type = b2_dynamicBody;
bd.position.Set(-14.0f + 2.0f * i, 15.0f);
b2Body* body = m_world->CreateBody(&bd);
body->CreateFixture(&fd);
b2Vec2 anchor(-15.0f + 2.0f * i, 15.0f);
jd.Initialize(prevBody, body, anchor);
b2AngularStiffness(jd.stiffness, jd.damping, frequencyHz, dampingRatio, jd.bodyA, jd.bodyB);
m_world->CreateJoint(&jd);
prevBody = body;
}
}
{
b2PolygonShape shape;
shape.SetAsBox(0.5f, 0.125f);
b2FixtureDef fd;
fd.shape = &shape;
fd.density = 20.0f;
b2WeldJointDef jd;
b2Body* prevBody = ground;
for (int32 i = 0; i < e_count; ++i)
{
b2BodyDef bd;
bd.type = b2_dynamicBody;
bd.position.Set(-4.5f + 1.0f * i, 5.0f);
b2Body* body = m_world->CreateBody(&bd);
body->CreateFixture(&fd);
if (i > 0)
{
b2Vec2 anchor(-5.0f + 1.0f * i, 5.0f);
jd.Initialize(prevBody, body, anchor);
m_world->CreateJoint(&jd);
}
prevBody = body;
}
}
{
b2PolygonShape shape;
shape.SetAsBox(0.5f, 0.125f);
b2FixtureDef fd;
fd.shape = &shape;
fd.density = 20.0f;
b2WeldJointDef jd;
float frequencyHz = 8.0f;
float dampingRatio = 0.7f;
b2Body* prevBody = ground;
for (int32 i = 0; i < e_count; ++i)
{
b2BodyDef bd;
bd.type = b2_dynamicBody;
bd.position.Set(5.5f + 1.0f * i, 10.0f);
b2Body* body = m_world->CreateBody(&bd);
body->CreateFixture(&fd);
if (i > 0)
{
b2Vec2 anchor(5.0f + 1.0f * i, 10.0f);
jd.Initialize(prevBody, body, anchor);
b2AngularStiffness(jd.stiffness, jd.damping, frequencyHz, dampingRatio, prevBody, body);
m_world->CreateJoint(&jd);
}
prevBody = body;
}
}
for (int32 i = 0; i < 2; ++i)
{
b2Vec2 vertices[3];
vertices[0].Set(-0.5f, 0.0f);
vertices[1].Set(0.5f, 0.0f);
vertices[2].Set(0.0f, 1.5f);
b2PolygonShape shape;
shape.Set(vertices, 3);
b2FixtureDef fd;
fd.shape = &shape;
fd.density = 1.0f;
b2BodyDef bd;
bd.type = b2_dynamicBody;
bd.position.Set(-8.0f + 8.0f * i, 12.0f);
b2Body* body = m_world->CreateBody(&bd);
body->CreateFixture(&fd);
}
for (int32 i = 0; i < 2; ++i)
{
b2CircleShape shape;
shape.m_radius = 0.5f;
b2FixtureDef fd;
fd.shape = &shape;
fd.density = 1.0f;
b2BodyDef bd;
bd.type = b2_dynamicBody;
bd.position.Set(-6.0f + 6.0f * i, 10.0f);
b2Body* body = m_world->CreateBody(&bd);
body->CreateFixture(&fd);
}
}
static Test* Create()
{
return new Cantilever;
}
b2Body* m_middle;
};
static int testIndex = RegisterTest("Joints", "Cantilever", Cantilever::Create);