mirror of https://github.com/axmolengine/axmol.git
146 lines
3.6 KiB
C++
146 lines
3.6 KiB
C++
/*
|
|
* Copyright (c) 2006-2010 Erin Catto http://www.box2d.org
|
|
*
|
|
* This software is provided 'as-is', without any express or implied
|
|
* warranty. In no event will the authors be held liable for any damages
|
|
* arising from the use of this software.
|
|
* Permission is granted to anyone to use this software for any purpose,
|
|
* including commercial applications, and to alter it and redistribute it
|
|
* freely, subject to the following restrictions:
|
|
* 1. The origin of this software must not be misrepresented; you must not
|
|
* claim that you wrote the original software. If you use this software
|
|
* in a product, an acknowledgment in the product documentation would be
|
|
* appreciated but is not required.
|
|
* 2. Altered source versions must be plainly marked as such, and must not be
|
|
* misrepresented as being the original software.
|
|
* 3. This notice may not be removed or altered from any source distribution.
|
|
*/
|
|
|
|
#ifndef ROPE_JOINT_H
|
|
#define ROPE_JOINT_H
|
|
|
|
/// This test shows how a rope joint can be used to stabilize a chain of
|
|
/// bodies with a heavy payload. Notice that the rope joint just prevents
|
|
/// excessive stretching and has no other effect.
|
|
/// By disabling the rope 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 RopeJoint : public Test
|
|
{
|
|
public:
|
|
RopeJoint()
|
|
{
|
|
b2Body* ground = NULL;
|
|
{
|
|
b2BodyDef bd;
|
|
ground = m_world->CreateBody(&bd);
|
|
|
|
b2EdgeShape shape;
|
|
shape.Set(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 float32 y = 15.0f;
|
|
m_ropeDef.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)
|
|
{
|
|
shape.SetAsBox(1.5f, 1.5f);
|
|
fd.density = 100.0f;
|
|
fd.filter.categoryBits = 0x0002;
|
|
bd.position.Set(1.0f * i, y);
|
|
bd.angularDamping = 0.4f;
|
|
}
|
|
|
|
b2Body* body = m_world->CreateBody(&bd);
|
|
|
|
body->CreateFixture(&fd);
|
|
|
|
b2Vec2 anchor(float32(i), y);
|
|
jd.Initialize(prevBody, body, anchor);
|
|
m_world->CreateJoint(&jd);
|
|
|
|
prevBody = body;
|
|
}
|
|
|
|
m_ropeDef.localAnchorB.SetZero();
|
|
|
|
float32 extraLength = 0.01f;
|
|
m_ropeDef.maxLength = N - 1.0f + extraLength;
|
|
m_ropeDef.bodyB = prevBody;
|
|
}
|
|
|
|
{
|
|
m_ropeDef.bodyA = ground;
|
|
m_rope = m_world->CreateJoint(&m_ropeDef);
|
|
}
|
|
}
|
|
|
|
void Keyboard(unsigned char key)
|
|
{
|
|
switch (key)
|
|
{
|
|
case 'j':
|
|
if (m_rope)
|
|
{
|
|
m_world->DestroyJoint(m_rope);
|
|
m_rope = NULL;
|
|
}
|
|
else
|
|
{
|
|
m_rope = m_world->CreateJoint(&m_ropeDef);
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
void Step(Settings* settings)
|
|
{
|
|
Test::Step(settings);
|
|
m_debugDraw.DrawString(5, m_textLine, "Press (j) to toggle the rope joint.");
|
|
m_textLine += DRAW_STRING_NEW_LINE;
|
|
if (m_rope)
|
|
{
|
|
m_debugDraw.DrawString(5, m_textLine, "Rope ON");
|
|
}
|
|
else
|
|
{
|
|
m_debugDraw.DrawString(5, m_textLine, "Rope OFF");
|
|
}
|
|
m_textLine += DRAW_STRING_NEW_LINE;
|
|
}
|
|
|
|
static Test* Create()
|
|
{
|
|
return new RopeJoint;
|
|
}
|
|
|
|
b2RopeJointDef m_ropeDef;
|
|
b2Joint* m_rope;
|
|
};
|
|
|
|
#endif
|