public Rope()
{
const int N = 40;
b2Vec2[] vertices = new b2Vec2[N];
float[] masses = new float[N];
for (int i = 0; i < N; ++i)
{
vertices[i].Set(0.0f, 20.0f - 0.25f * i);
masses[i] = 1.0f;
}
masses[0] = 0.0f;
masses[1] = 0.0f;
b2RopeDef def = new b2RopeDef();
def.vertices = vertices;
def.count = N;
def.gravity.Set(0.0f, -10.0f);
def.masses = masses;
def.damping = 0.1f;
def.k2 = 1.0f;
def.k3 = 0.5f;
m_rope.Initialize(def);
m_angle = 0.0f;
m_rope.SetAngle(m_angle);
}
///
public void Initialize(b2RopeDef def)
{
Debug.Assert(def.count >= 3);
m_count = def.count;
m_ps = Arrays.InitializeWithDefaultInstances <b2Vec2>(m_count);
m_p0s = Arrays.InitializeWithDefaultInstances <b2Vec2>(m_count);
m_vs = Arrays.InitializeWithDefaultInstances <b2Vec2>(m_count);
m_ims = Arrays.InitializeWithDefaultInstances <float>(m_count);
for (int i = 0; i < m_count; ++i)
{
m_ps[i] = def.vertices[i];
m_p0s[i] = def.vertices[i];
m_vs[i].SetZero();
float m = def.masses[i];
if (m > 0.0f)
{
m_ims[i] = 1.0f / m;
}
else
{
m_ims[i] = 0.0f;
}
}
int count2 = m_count - 1;
int count3 = m_count - 2;
m_Ls = new float[count2];
m_as = new float[count3];
for (int i = 0; i < count2; ++i)
{
b2Vec2 p1 = m_ps[i];
b2Vec2 p2 = m_ps[i + 1];
m_Ls[i] = Utils.b2Distance(p1, p2);
}
for (int i = 0; i < count3; ++i)
{
b2Vec2 p1 = m_ps[i];
b2Vec2 p2 = m_ps[i + 1];
b2Vec2 p3 = m_ps[i + 2];
b2Vec2 d1 = p2 - p1;
b2Vec2 d2 = p3 - p2;
float a = Utils.b2Cross(d1, d2);
float b = Utils.b2Dot(d1, d2);
m_as[i] = (float)Math.Atan2(a, b);
}
m_gravity = def.gravity;
m_damping = def.damping;
m_k2 = def.k2;
m_k3 = def.k3;
}
