// http://shspage.com/aijs/
private void Metaball(SVGData svg, Vector2 c1, float r1, Vector2 c2, float r2, float v)
{
if (r1 == 0f || r2 == 0f)
{
return;
}
var pi2 = Mathf.PI / 2f;
var d = (c2 - c1).magnitude;
var u1 = 0f;
var u2 = 0f;
if (d <= Mathf.Abs(r1 - r2))
{
return;
}
else if (d < r1 + r2)
{
// case circles are overlapping
u1 = Mathf.Acos((r1 * r1 + d * d - r2 * r2) / (2 * r1 * d));
u2 = Mathf.Acos((r2 * r2 + d * d - r1 * r1) / (2 * r2 * d));
}
var t1 = Mathf.Atan2(c2.y - c1.y, c2.x - c1.x);
var t2 = Mathf.Acos((r1 - r2) / d);
var t1a = t1 + u1 + (t2 - u1) * v;
var t1b = t1 - u1 - (t2 - u1) * v;
var t2a = t1 + Mathf.PI - u2 - (Mathf.PI - u2 - t2) * v;
var t2b = t1 - Mathf.PI + u2 + (Mathf.PI - u2 - t2) * v;
var p1a = PointOnCircle(c1, t1a, r1);
var p1b = PointOnCircle(c1, t1b, r1);
var p2a = PointOnCircle(c2, t2a, r2);
var p2b = PointOnCircle(c2, t2b, r2);
// define handle length by the distance between both ends of the curve to draw
var handle_len_rate = 2;
var d2 = Mathf.Min(v * handle_len_rate, (p2a - p1a).magnitude / (r1 + r2));
d2 *= Mathf.Min(1, d * 2 / (r1 + r2)); // case circles are overlapping
r1 *= d2;
r2 *= d2;
svg.Move(p1a);
svg.Curve(PointOnCircle(p1a, t1a - pi2, r1), PointOnCircle(p2a, t2a + pi2, r2), p2a);
svg.Line(p2b);
svg.Curve(PointOnCircle(p2b, t2b - pi2, r2), PointOnCircle(p1b, t1b + pi2, r1), p1b);
svg.Line(p1a);
}
private void Circle(SVGData svg, Vector2 c, float r)
{
for (var i = 0; i < 4; ++i)
{
var angle0 = Mathf.PI * 0.5f * (i + 0);
var angle1 = Mathf.PI * 0.5f * (i + 1);
var x0 = c.x + Mathf.Cos(angle0) * r;
var y0 = c.y - Mathf.Sin(angle0) * r;
var x1 = c.x + Mathf.Cos(angle1) * r;
var y1 = c.y - Mathf.Sin(angle1) * r;
var a = r * (4f / 3f) * Mathf.Tan((angle1 - angle0) / 4f);
var inAngle = angle0 + Mathf.PI * 0.5f;
var inX = x0 + Mathf.Cos(inAngle) * a;
var inY = y0 - Mathf.Sin(inAngle) * a;
var outAngle = angle1 - Mathf.PI * 0.5f;
var outX = x1 + Mathf.Cos(outAngle) * a;
var outY = y1 - Mathf.Sin(outAngle) * a;
if (i == 0)
{
svg.Move(x0, y0);
}
svg.Curve(inX, inY, outX, outY, x1, y1);
}
}
void Update()
{
SVG.Clear();
for (var i = 0; i < 4; ++i)
{
var angle0 = Mathf.PI * 0.5f * (i + 0);
var angle1 = Mathf.PI * 0.5f * (i + 1);
var r = 3f;
var x0 = Mathf.Cos(angle0) * r;
var y0 = Mathf.Sin(angle0) * r;
var x1 = Mathf.Cos(angle1) * r;
var y1 = Mathf.Sin(angle1) * r;
var a = r * (4f / 3f) * Mathf.Tan((angle1 - angle0) / 4f);
var inAngle = angle0 + Mathf.PI * 0.5f;
var inX = x0 + Mathf.Cos(inAngle) * a;
var inY = y0 + Mathf.Sin(inAngle) * a;
var outAngle = angle1 - Mathf.PI * 0.5f;
var outX = x1 + Mathf.Cos(outAngle) * a;
var outY = y1 + Mathf.Sin(outAngle) * a;
if (i == 0)
{
SVG.Move(x0, y0);
}
SVG.Curve(inX, inY, outX, outY, x1, y1);
}
Mesh.Fill(SVG);
}
private void DrawR(SVGData svg, Vector2 p, Vector2 pPrev, Vector2 pNext, float r, Matrix4x4 matrix, bool first = false)
{
var angle0 = Mathf.Atan2(p.y - pNext.y, p.x - pNext.x);
var angle1 = Mathf.Atan2(p.y - pPrev.y, p.x - pPrev.x);
if (angle0 > angle1)
{
angle0 = angle0 - Mathf.PI * 2f;
}
var angleBetween = Mathf.Lerp(angle0, angle1, 0.5f);
var cx = p.x - Mathf.Cos(angleBetween) * r * Mathf.Sqrt(2f);
var cy = p.y - Mathf.Sin(angleBetween) * r * Mathf.Sqrt(2f);
var x0 = cx + Mathf.Cos(angle0) * r;
var y0 = cy + Mathf.Sin(angle0) * r;
var x1 = cx + Mathf.Cos(angle1) * r;
var y1 = cy + Mathf.Sin(angle1) * r;
var a = r * (4f / 3f) * Mathf.Tan((angle1 - angle0) / 4f);
var inAngle = angle0 + Mathf.PI * 0.5f;
var inX = x0 + Mathf.Cos(inAngle) * a;
var inY = y0 + Mathf.Sin(inAngle) * a;
var outAngle = angle1 - Mathf.PI * 0.5f;
var outX = x1 + Mathf.Cos(outAngle) * a;
var outY = y1 + Mathf.Sin(outAngle) * a;
var p0 = matrix.MultiplyPoint(new Vector3(x0, y0));
var p1 = matrix.MultiplyPoint(new Vector3(x1, y1));
var pIn = matrix.MultiplyPoint(new Vector3(inX, inY));
var pOut = matrix.MultiplyPoint(new Vector3(outX, outY));
if (first)
{
svg.Move(p0);
}
else
{
svg.Line(p0);
}
svg.Curve(pIn, pOut, p1);
}