public Spring(PointMass pointmass_a, PointMass pointmass_b, float k, float damping, float length)
{
this.pointmass_a = pointmass_a;
this.pointmass_b = pointmass_b;
this.d = length;
this.k = k;
this.damping = damping;
}
public void Clear()
{
body_a = body_b = null;
pointmass_a = pointmass_b = pointmass_c = new PointMass();
edge_distance = 0f;
point = Vector2.Zero;
normal = Vector2.Zero;
penetration = 0f;
}
public Body(Shape shape, float mass)
{
this.base_shape = shape;
this.curr_shape = shape.Clone();
this.count = shape.count;
this.pointmass_list = new PointMass[shape.count];
for (int i = 0; i < shape.count; i++)
pointmass_list[i] = new PointMass(shape.points[i], mass);
this.bitmaskx = new Bitmask();
this.bitmasky = new Bitmask();
}
public Chain(PointMass from, PointMass to, int count, float k, float damping, float mass)
{
this.damping = 0.99f;
this.pointmass_list = new List<PointMass>();
this.spring_list = new List<Spring>();
float length = Vector2.Distance(from.position, to.position) / count;
Vector2 direction = to.position - from.position;
direction.Normalize();
for (int i = 0; i < count+1; i++)
pointmass_list.Add(new PointMass(new Vector2(from.position.X + direction.X * length * i, from.position.Y + direction.Y * length* i), mass));
pointmass_list[0] = from;
pointmass_list[count] = to;
for (int i = 1; i < count+1; i++)
spring_list.Add(new Spring(pointmass_list[i - 1], pointmass_list[i - 0], k, damping));
}
public Spring(PointMass pointmass_a, PointMass pointmass_b, float k, float damping)
: this(pointmass_a, pointmass_b, k, damping, 0)
{
Reset();
}
public void RenderOutlines(PointMass[] points)
{
Color color = Color.White;
int i;
for (i = 0; i < points.Length - 1; i++)
{
linebatch.Add(new LineVertex(new Vector3(points[i].position.X, points[i].position.Y, 0), color));
linebatch.Add(new LineVertex(new Vector3(points[i + 1].position.X, points[i + 1].position.Y, 0), color));
}
linebatch.Add(new LineVertex(new Vector3(points[i].position.X, points[i].position.Y, 0), color));
linebatch.Add(new LineVertex(new Vector3(points[0].position.X, points[0].position.Y, 0), color));
}
public void RenderNormals(PointMass[] points)
{
Color color = Color.Purple;
float size = 0.1f;
int prevPt, nextPt;
Vector2 pt, prev, next, fromPrev, toNext, ptNorm;
fromPrev = toNext = ptNorm = new Vector2();
for (int i = 0; i < points.Length; i++)
{
pt = points[i].position;
prevPt = (i > 0) ? i - 1 : points.Length - 1;
nextPt = (i < points.Length - 1) ? i + 1 : 0;
prev = points[prevPt].position;
next = points[nextPt].position;
fromPrev.X = pt.X - prev.X;
fromPrev.Y = pt.Y - prev.Y;
toNext.X = next.X - pt.X;
toNext.Y = next.Y - pt.Y;
fromPrev.Normalize();
toNext.Normalize();
ptNorm.X = -(fromPrev.Y + toNext.Y);
ptNorm.Y = fromPrev.X + toNext.X;
ptNorm.Normalize();
linebatch.Add(new LineVertex(new Vector3(pt.X, pt.Y, 0), color));
linebatch.Add(new LineVertex(new Vector3(pt.X + ptNorm.X * size, pt.Y + ptNorm.Y * size, 0), color));
}
}
