public ApplyForce()
{
m_world.Gravity = new Vec2(0.0f, 0.0f);
const float k_restitution = 0.4f;
Body ground;
{
BodyDef bd = new BodyDef();
bd.Position = new Vec2(0.0f, 20.0f);
ground = m_world.CreateBody(bd);
PolygonShape shape = new PolygonShape();
FixtureDef sd = new FixtureDef();
sd.Shape = shape;
sd.Density = 0.0f;
sd.Restitution = k_restitution;
// Left vertical
shape.SetAsEdge(new Vec2(-20.0f, -20.0f), new Vec2(-20.0f, 20.0f));
ground.CreateFixture(sd);
// Right vertical
shape.SetAsEdge(new Vec2(20.0f, -20.0f), new Vec2(20.0f, 20.0f));
ground.CreateFixture(sd);
// Top horizontal
shape.SetAsEdge(new Vec2(-20.0f, 20.0f), new Vec2(20.0f, 20.0f));
ground.CreateFixture(sd);
// Bottom horizontal
shape.SetAsEdge(new Vec2(-20.0f, -20.0f), new Vec2(20.0f, -20.0f));
ground.CreateFixture(sd);
}
{
Transform xf1 = new Transform();
xf1.R = new Mat22(0.3524f * (float)Math.PI);
xf1.Position = (xf1.R * new Vec2(1.0f, 0.0f));
Vec2[] vertices = new Vec2[3]
{
(xf1 * new Vec2(-1.0f, 0.0f)),
(xf1 * new Vec2(1.0f, 0.0f)),
(xf1 * new Vec2(0.0f, 0.5f))
};
PolygonShape poly1 = new PolygonShape(vertices);
FixtureDef sd1 = new FixtureDef();
sd1.Shape = poly1;
sd1.Density = 4.0f;
Transform xf2 = new Transform();
xf2.R = new Mat22(-0.3524f * (float)Math.PI);
xf2.Position = (xf2.R * new Vec2(-1.0f, 0.0f));
vertices = new Vec2[]
{
(xf2 * new Vec2(-1.0f, 0.0f)),
(xf2 * new Vec2(1.0f, 0.0f)),
(xf2 * new Vec2(0.0f, 0.5f))
};
PolygonShape poly2 = new PolygonShape(vertices);
FixtureDef sd2 = new FixtureDef();
sd2.Shape = poly2;
sd2.Density = 2.0f;
BodyDef bd = new BodyDef();
bd.BodyType = BodyType.Dynamic;
bd.AngularDamping = 5.0f;
bd.LinearDamping = 0.1f;
bd.Position = new Vec2(0.0f, 2.0f);
bd.Angle = (float)Math.PI;
bd.AllowSleep = false;
m_body = m_world.CreateBody(bd);
m_body.CreateFixture(sd1);
m_body.CreateFixture(sd2);
}
{
PolygonShape shape = new PolygonShape();
shape.SetAsBox(0.5f, 0.5f);
FixtureDef fd = new FixtureDef();
fd.Shape = shape;
fd.Density = 1.0f;
fd.Friction = 0.3f;
for (int i = 0; i < 10; ++i)
{
BodyDef bd = new BodyDef();
bd.BodyType = BodyType.Dynamic;
bd.Position = new Vec2(0.0f, 5.0f + 1.54f * i);
Body body = m_world.CreateBody(bd);
body.CreateFixture(fd);
float gravity = 10.0f;
float I = body.Inertia;
float mass = body.Mass;
// For a circle: I = 0.5 * m * r * r ==> r = sqrt(2 * I / m)
float radius = (float)Math.Sqrt(2.0f * I / mass);
FrictionJointDef jd = new FrictionJointDef();
jd.LocalAnchorA = jd.LocalAnchorB = Vec2.Empty;
jd.BodyA = ground;
jd.BodyB = body;
jd.CollideConnected = true;
jd.MaxForce = mass * gravity;
jd.MaxTorque = mass * radius * gravity;
m_world.CreateJoint(jd);
}
}
}
public Mirrors()
{
m_world.Gravity = new Vec2(0.0f, 0.0f);
{
Body body = m_world.CreateBody(new BodyDef());
}
{
float startY = 0;
FrictionJointDef jd = new FrictionJointDef();
BodyDef bd = new BodyDef();
bd.BodyType = BodyType.Dynamic;
PolygonShape shape = new PolygonShape(1.0f, 0.25f);
for (int i = 0; i < 20; ++i)
{
bd.Position = new Vec2(0, startY);
startY += 1.5f;
FixtureDef fix = new FixtureDef(shape, 1.0f);
var body = m_world.CreateBody(bd);
var ff = body.CreateFixture(fix);
float I = body.Inertia;
float mass = body.Mass; float radius = (float)Math.Sqrt(2.0f * I / mass);
jd.LocalAnchorA = jd.LocalAnchorB = Vec2.Empty;
jd.BodyA = m_groundBody;
jd.BodyB = body;
jd.CollideConnected = true;
jd.MaxForce = body.Mass * 10.0f;
jd.MaxTorque = body.Mass * radius * 10.0f;
m_world.CreateJoint(jd);
}
}
}
