/// <summary>
/// Creates a new rectangle shaped sub-path.
/// </summary>
public static void Rect(this Nvg nvg, Rectangle <float> rect)
{
InstructionQueue queue = nvg.instructionQueue;
queue.AddMoveTo(rect.Origin);
queue.AddLineTo(new(rect.Origin.X, rect.Max.Y));
queue.AddLineTo(rect.Max);
queue.AddLineTo(new(rect.Max.X, rect.Origin.Y));
queue.AddClose();
}
/// <summary>
/// Creates new circle arc shaped sub-path.
/// The arc is drawn from angle a0 to a1.
/// </summary>
/// <param name="c">The arc center.</param>
/// <param name="r">The arc radius.</param>
/// <param name="dir">The direction the arc is swept in.</param>
public static void Arc(this Nvg nvg, Vector2D <float> c, float r, float a0, float a1, Winding dir)
{
Vector2D <float> pPos = default;
Vector2D <float> pTan = default;
InstructionQueue queue = nvg.instructionQueue;
bool line = queue.Count > 0;
float da = a1 - a0;
if (dir == Winding.Cw)
{
if (MathF.Abs(da) >= MathF.PI * 2.0f)
{
da = MathF.PI * 2.0f;
}
else
{
while (da < 0.0f)
{
da += MathF.PI * 2.0f;
}
}
}
else
{
if (MathF.Abs(da) >= MathF.PI * 2.0f)
{
da = -MathF.PI * 2.0f;
}
else
{
while (da > 0.0f)
{
da -= MathF.PI * 2.0f;
}
}
}
int ndivs = Math.Max(1, Math.Min((int)(MathF.Abs(da) / (MathF.PI * 0.5f) + 0.5f), 5));
float hda = (da / (float)ndivs) / 2.0f;
float kappa = MathF.Abs(4.0f / 3.0f * (1.0f - MathF.Cos(hda)) / MathF.Sin(hda));
if (dir == Winding.Ccw)
{
kappa *= -1.0f;
}
for (int i = 0; i <= ndivs; i++)
{
float alpha = a0 + da * ((float)i / (float)ndivs);
Vector2D <float> d = new(MathF.Cos(alpha), MathF.Sin(alpha));
Vector2D <float> pos = new(c.X + d.X * r, c.Y + d.Y * r);
Vector2D <float> tan = new(-d.Y * r * kappa, d.X *r *kappa);
if (i == 0)
{
if (line)
{
queue.AddLineTo(pos);
}
else
{
queue.AddMoveTo(pos);
}
}
else
{
queue.AddBezierTo(pPos + pTan, pos - tan, pos);
}
pPos = pos;
pTan = tan;
}
}