[LIBGDX学习]LibGDX代码详解（十三）Box2D wield joint

public class Cantilever extends Box2DTest {
Body m_middle;
final int e_count = 10;// ori 8

@Override
protected void createWorld (World world) {
Body ground;
{
BodyDef bd = new BodyDef();
ground = world.createBody(bd);

EdgeShape shape = new EdgeShape();
shape.set(new Vector2(-40, 0), new Vector2(40, 0));
ground.createFixture(shape, 0);
shape.dispose();
}

{
PolygonShape shape = new PolygonShape();
shape.setAsBox(0.5f, 0.125f);

FixtureDef fd = new FixtureDef();
fd.shape = shape;
fd.density = 20.0f;

WeldJointDef jd = new WeldJointDef();// 就像焊接起来那样的关节？比较刚硬？

Body prevBody = ground;
for (int i = 0; i < e_count; i++) {
BodyDef bd = new BodyDef();
bd.type = BodyType.DynamicBody;
bd.position.set(-14.5f + 1.0f * i, 5.0f);// ground body起点是x零y零？
Body body = world.createBody(bd);
body.createFixture(fd);

Vector2 anchor = new Vector2(-15.0f + 1 * i, 5.0f);
jd.initialize(prevBody, body, anchor);
world.createJoint(jd);
prevBody = body;
}

shape.dispose();
}

{
PolygonShape shape = new PolygonShape();
shape.setAsBox(0.5f, 0.125f);

FixtureDef fd = new FixtureDef();
fd.shape = shape;
fd.density = 20.0f;

WeldJointDef jd = new WeldJointDef();

Body prevBody = ground;
for (int i = 0; i < e_count; i++) {
BodyDef bd = new BodyDef();
bd.type = BodyType.DynamicBody;
bd.position.set(-14.5f + 1.0f * i, 15.0f);
bd.gravityScale = 10.0f;
Body body = world.createBody(bd);
body.createFixture(fd);

Vector2 anchor = new Vector2(-15.0f + 1.0f * i, 15.0f);
jd.initialize(prevBody, body, anchor);
world.createJoint(jd);

prevBody = body;
}

shape.dispose();
}

{
PolygonShape shape = new PolygonShape();
shape.setAsBox(0.5f, 0.125f);

FixtureDef fd = new FixtureDef();
fd.shape = shape;
fd.density = 20.0f;

WeldJointDef jd = new WeldJointDef();

Body prevBody = ground;
for (int i = 0; i < e_count*0.5f; i++) {
BodyDef bd = new BodyDef();
bd.type = BodyType.DynamicBody;
bd.position.set(-4.5f + 1.0f * i, 5.0f);
Body body = world.createBody(bd);
body.createFixture(fd);

if (i > 0) {// 不和地面连接？
Vector2 anchor = new Vector2(-5.0f + 1.0f * i, 5.0f);
jd.initialize(prevBody, body, anchor);
world.createJoint(jd);
}

prevBody = body;
}

shape.dispose();
}

{
PolygonShape shape = new PolygonShape();
shape.setAsBox(0.5f, 0.125f);

FixtureDef fd = new FixtureDef();
fd.shape = shape;
fd.density = 20.0f;

WeldJointDef jd = new WeldJointDef();

Body prevBody = ground;
for (int i = 0; i < e_count*0.4f; i++) {
BodyDef bd = new BodyDef();
bd.type = BodyType.DynamicBody;
bd.position.set(5.5f + 1.0f * i, 10.0f);
bd.gravityScale = 10.0f;
Body body = world.createBody(bd);
body.createFixture(fd);

if (i > 0) {
Vector2 anchor = new Vector2(5.0f + 1.0f * i, 10.0f);
jd.initialize(prevBody, body, anchor);
world.createJoint(jd);
}

prevBody = body;
}

shape.dispose();
}

for (int i = 0; i < 2; i++) {
Vector2[] vertices = new Vector2[3];
vertices[0] = new Vector2(-0.5f, 0);
vertices[1] = new Vector2(0.5f, 0);
vertices[2] = new Vector2(0, 1.5f);

PolygonShape shape = new PolygonShape();
shape.set(vertices);

FixtureDef fd = new FixtureDef();
fd.shape = shape;
fd.density = 1.0f;

BodyDef bd = new BodyDef();
bd.type = BodyType.DynamicBody;
bd.position.set(-8.0f + 8.0f * i, 12.0f);
Body body = world.createBody(bd);
body.createFixture(fd);

shape.dispose();
}

for (int i = 0; i < 2; i++) {
CircleShape shape = new CircleShape();
shape.setRadius(0.5f);

FixtureDef fd = new FixtureDef();
fd.shape = shape;
fd.density = 1.0f;

BodyDef bd = new BodyDef();
bd.type = BodyType.DynamicBody;
bd.position.set(-6.0f + 6.0f * i, 10.0f);
Body body = world.createBody(bd);
body.createFixture(fd);
shape.dispose();
}
}

}